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Power Management ICs for Automotive Body Control

LED Drivers

for Automotive Light

BD8381EFV-M

●Description

BD8381EFV-M is a white LED driver with the capability of withstanding high input voltage (50V MAX).

A current-mode buck-boost DC/DC controller is also integrated to achieve stable operation against voltage input and also to

remove the constraint of the number of LEDs in series connection.

The brightness can be controlled by either PWM or linear. The PWM brightness signal generation circuit is built into, and

the control without microcomputer is also possible.

●Features

1) Input voltage range 5.0 – 30 V

2) Integrated buck-boost current-mode DC/DC controller

3) Built-in CR timer for PWM brightness

4) PWM linear brightness

5) Built-in protection functions (UVLO, OVP, TSD, OCP, SCP)

6) LED error status detection function (OPEN/ SHORT)

7) HTSSOP-B28 package

●Applications

Headlight and running (DRL) of night of daylight, etc.

●Absolute maximum ratings (Ta=25℃)

Parameter Symbol Ratings Unit

Power supply voltage VCC 50 V

BOOT Voltage VBOOT 55 V

SW,CS,OUTH Voltage VSW, VCS, VOUTH 50 V

BOOT-SW Voltage VBOOT-SW 7 V

VREG,OVP,OUTL,FAIL1,FAIL2,THM,SS,

COMP,RT,SYNC,EN,DISC,VTH,FB,LEDR,

LEDC,DRLIN, PWMOUT,CT Voltage

VVREG,VOVP,VOUTL,VFAIL1,VFAIL2,VTHM,VSS,

VCOMP,VRT,VSYNCVEN,VDISC,VVTH,VFB,VLEDR,

VLEDC, ,VDRLIN,VPWMOUT VCT -0.3～7 < VCC V

Power Consumption Pd 1.45※1 W

Operating temperature range Topr -40～+125 ℃

Storage temperature range Tstg -55～+150 ℃

Junction temperature Tjmax 150 ℃

※1 IC mounted on glass epoxy board measuring 70mm×70mm×1.6mm, power dissipated at a rate of 11.6mW/℃ at temperatures above 25℃.

※2 A radiation is not designed.

●Operating conditions (Ta=25℃)

Parameter Symbol Ratings Unit

Power supply voltage VCC 5.0～30 V

Oscillating frequency range FOSC 200～600 kHz

External synchronization frequency range ※3 ※4FSYNC fosc～600 kHz

External synchronization pulse duty range FSDUTY 40～60 %

※3 Connect SYNC to GND or OPEN when not using external frequency synchronization.

※4 Do not switch between internal and external synchronization when an external synchronization signal is input to the device.

No.11039ECT14

’3VRE 1 ’3VRE

Technical Note

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BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Electrical characteristics (Unless otherwise specified, VCC=12V Ta=25℃)

Parameter Symbol

Limits Unit Conditions

Min Typ Max.

Circuit current ICC - 4.5 7.0 mA EN=Hi, SYNC=Hi,

RT=OPEN, CIN=10µF

Standby current IST - 0 8 µA EN=Low

[VREG Block (VREG)]

Reference voltage VREG 4.5 5.0 5.5 V IREG=-5mA，CREG=10µF

[OUTH Block]

OUTH high-side ON resistance RONHH 1.5 3.5 7.0 Ω ION=-10mA

OUTH low-side ON resistance RONHL 1.0 2.5 5.0 Ω ION=10mA

Over-current protection

operating voltage VOLIMIT VCC

-0.68 VCC

-0.60 VCC

-0.52 V

SS charge current ISS 3 5 7 uA VSS=0V

[OUTL Block]

OUTL high-side ON resistance RONLH 2.0 4.0 8.0 Ω ION=-10mA

OUTL low –side ON resistance RONLL 1.0 2.5 5.0 Ω ION=10mA

[SW Block]

SW low -side ON resistance RONSW 2.0 4.5 9.0 Ω IONSW=10mA

[PWMOUT Block]

PWMOUT high-side ON resistance RONPWMH 2.0 4.0 8.0 Ω IONPWMH=-10mA

PWMOUT low-side ON resistance RONPWML 1.0 2.5 5.0 Ω IONPWML=10mA

[Error Amplifier Block]

Reference voltage1 VREF1 0.194 0.200 0.206 V FB-COMP Short,1MΩ/250kΩ

Reference voltage2 VREF2 0.190 0.200 0.210 V FB-COMP Short,1MΩ/250kΩ

Ta=-40℃～125℃

COMP sink current ICOMPSINK 50 75 100 µA VFB>0.2V, Vcomp=1V

COMP source current ICOMPSOURCE -100 -75 -50 µA VFB <0.2V, Vcomp=1V

Max Duty output Dmax 83 90 - % FOSC=300KHz

[Oscillator Block]

Oscillating frequency FOSC 285 300 315 KHz RT=200kΩ

[OVP Block]

Over-voltage detection reference voltage VOVP 1.9 2.0 2.1 V VOVP=Sweep up

OVP hysteresis width VOHYS 0.45 0.55 0.65 V VOVP= Sweep down

[UVLO Block ]

UVLO voltage VUVLO 4.0 4.35 4.7 V VCC : Sweep down

UVLO hysteresis width VUHYS 50 150 250 mV VCC : Sweep up

[PWM Generation circuit Block]

VTH Threshold voltage VTH1 3 2/3VREG 3.7 V

VTH Threshold voltage VTH2 1 1/3VREG 2 V

PWM minimum ON width TPWMON 25 - - µs

LED OPEN detection function VOPEN 30 50 70 mV

LED SHORT detection function VSHORT 100 200 400 mV VSHORT≧lVLEDR-VLEDCl

LED GND short protection timer TSHORT 100 150 200 ms CT=0.1µF

[Logic Inputs]

Input HIGH voltage VINH 3.0 - - V

Input LOW voltage VINL GND - 1.0 V

Input current 1 IIN 20 35 50 µA VIN=5V (SYNC/DRLIN)

Input current 2 IEN 15 30 45 µA VEN=5V (EN)

[FAIL Output (open drain) ]

FAIL LOW voltage VOL - 0.1 0.2 V IOL=0.1mA

◎ This product is not designed for use in radioactive environments.

BD8381EFV—M Technical Note .Electrlcal characteristic curves (Reference data) (Unless otherwise specified Ta:25“C) 5 E 8 g 4 E3 :3 z i S o o o 5 ioi52o253o354o455o vcc VOLTAGE M Fig.1 VREG Voltage characteristic oo (— 3 so § 3 / / LE to /’J E ﬁ/ 0 E E 7. 2o 3 o oo o 5 ioi52o253o254o455o suPPLv VOLTAGE Vcc M Fig.4 Circuit current (Switching OFF) zo VCC=i2V ; fan a > m iso 9 : aim L) E e 50 a o o Ell uzo: o4o5 Dawns us i n THM vomcETHMM Fig.7 THM Gain in VCC=l2V _ T345“ T = Aa‘c a a 8 Ia=i2 “c / 5 m 5 <5 5="" g4="" §="" 5="" 2="" o="" o="" o="" i="" 2="" 3="" 4="" 5="" en="" voltage="" ven="" m="" fig="" 10="" en="" threshold="" voltage="" output="" voltage="" voovosiv]="" 7oo="" on="" vcc="12V" vcc="12V" g="" am="" o2i5="" #="" e="" @5470="" s="" ei2i="" u="" .1="" 5="" 5="" c7255="" 2="" we="" frszﬂkuhm="" g="" '“="" m="" oz="" 5*="" we="" 2="" e="" e="" eiiss="" 2="" 2‘“="" m="" we="" i="" k="" 8="" “t“="" e="" eiibs="" 3="" n="" no="" 75o="" 25="" o="" 25="" 5o="" 75="" we="" l25="" 75o="" .25="" o="" 25="" 5o="" 75="" ioo="" (z="" temperaturetaiioi="" temperature="" tom="" fig.2="" 080="" temperature="" characteristic="" fig.3="" standard="" voltage="" temperature="" characteristic="" o="" 55="" ‘="" ‘="" ion="" vccz‘zv="" 95="" ileo="o54" o="" 54="" ;="" o52="" g="" an="" g="" 35="" m="" use="" 3="" an="" ’3="" o5s="" 9="" 75="" §="" 7..="" swam="" e="" vaulzlav="" 3="" “55="" o="" 55="" o="" 54="" an="" .50="" 725="" o="" 25="" 5o="" 75="" ion="" i25="" 5="" 9="" ‘2="" ‘5="" ‘3="" 2‘="" temperature="" ta="" [”0]="" vcc="" voltage="" m="" fig.5="" overcurrent="" detection="" voltage="" fig.6="" elticiency="" temperature="" characteristic="" (input="" voltage="" dependence)="" io="" .="" io="" vcc="l2V" g="" a="" e="" a="" 7="" .m="" a="" a="" e="" e="" a="i\25‘" 9="" 6="" §="" 5="" o="" e="" s="" 4="" 9="" 4="" °="" l="" l="" *="" e="" 3="" 3="" a="" g="" 2="" e="" 2="" i="" t’svreg="" o="" i="" l="" o="" o="" i="" 2="" 3="" 4="" 5="" ‘7="" ‘wh="" mam“="" (2%="" m‘="" 5="" drljn="" voltage="" vdrlln="" m="" fig.8="" vth="" threshold="" voltage="" fig-9="" drlin="" threshold="" vollage="" 2i5="" .="" .="" vcc="l2V" _="" vcc="i2V" e="" 2i="" 2="" 9="" d="" m="" 2o5="" “‘="" e="" g="" e="" a-="" e="" 2="" .5="" 5=""> 5 / E v is5 3 i. 5 é: o g is 5 ia5 5o 25 o TEMPERATURETaVc] z 50 75 imi25 Fig.11 VREG voltage Temperature characteristic 5o 72 u 25 5o 75 IEMPERAIUREIAFC] Fig.12 OVF voltage Temperature characteristic Too (5 www rohm.com © 2012 ROHM 00.. Ltd. All rights reserved. 3/23 2012.06 - Rev.C

Technical Note

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BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

012345

DRLIN VOLTAGE:VDRLIN [V]

OUTPUT VOLTAGE:VREG [V]

012345

VTH VOLTAGE:VVTH [V]

PWMOUT OUTPUT VOLTAGE [V]

0 5 10 15 20 25 30 35 40 45 50

VCC VOLTAGE [V]

OUTPUT VOLTAGE:VREG [V]

100

200

300

400

500

600

700

-50 -25 0 25 50 75 100 125

TEMPERATURE:Ta [℃]

SWITCHING FREQUENCY:FOSC [kHz]

0.0

2.0

4.0

6.0

8.0

0 5 10 15 20 25 30 35 40 45 50

SUPPLY VOLTAGE:Vcc [V]

OUTPUT CARRENT:Icc [mA]

0.18

0.185

0.19

0.195

0.2

0.205

0.21

0.215

0.22

-50 -25 0 25 50 75 100 125

TEMPERATURE:Ta [℃]

FB REFERENCE VOLTAGE [V]

100

150

200

250

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

THM VOLTAGE:THM[V]

REFERENCEVOLTAGE :VREF [mV]

Fig.7 THM Gain

012345

EN VOLTAGE:VEN [V]

OUTPUT VOLTAGE:VREG [V]

4.5

4.6

4.7

4.8

4.9

5.1

5.2

5.3

5.4

5.5

-5 0 -25 0 25 50 75 1 00 125

TEMPERATU RE:Ta [℃]

OUTPUT Voltage: VREG[V]

1.85

1.9

1.95

2.05

2.1

2.15

-50 -25 0 25 50 75 100 125

TEMPERATURE:Ta [℃]

Over voltage detection voltage: VOVP[V]

100

6 9 12 15 18 21

VCC VOLTAGE [V]

OUTPUT VOLTAGE:VREG [V]

●Electrical characteristic curves (Reference data)

(Unless otherwise specified, Ta=25℃)

Fig.1 VREG Voltage characteristic Fig.2 OSC Temperature characteristic

Fig.4 Circuit current

(Switching OFF)

Fig.3 Standard voltage

temperature characteristic

Fig.5 Overcurrent detection voltage

temperature characteristic

Fig.9 DRLIN Threshold voltage

Fig.8 VTH Threshold voltage

Fig.6 Efficiency

(Input voltage dependence)

0.54

0.56

0.58

0.60

0.62

0.64

0.66

-50-25 0 25 50 75100125

TEMPERATURE:Ta [℃]

OUTPUT VOLTAGE:Vcc-Vcs [V]

Fig.10 EN Threshold voltage

Ta=125℃

Ta=25℃ Ta=-40℃

VCC=12V

RT=100kohm

RT=200kohm

VCC=12V

VCC=12V VCC=12V

Fig.11 VREG voltage

Temperature characteristic

Ta=125℃

Ta=25℃ Ta=-40℃

Fig.12 OVP voltage

Temperature characteristic

VCC=12V

ILED=0.6A

Buck-Boost

Vout=14V

Boost

Vout=24V

Buck

Vout=6V

1/3VREG 2/3VREG

RT=100kohm

RT=200kohm

55 vccz‘zv _ E 350 5° E 55 § 300 § 50 § 50 \ 5 \ 2 \ ‘5 x 2m \ § \ ‘0 r E ‘50 35 n 30 4 ma ran 2 u 25 5D 75 mo ‘25 ran 725 o 25 an TEMPERMUREHFCI TEMPERAIUREI: H913 LED open delechon vollage . Temperalure characlenshc Flgjﬂiﬁgmx q wwwmhm.com 4/23 © 2012 ROHM Co” Ltd. A” nghts reserved.

Technical Note

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BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

-50 -25 0 25 50 75 100 125

TEMPERATURE:Ta [℃]

LED open detection voltage[mV]

100

150

200

250

300

350

400

-50 -25 0 25 50 75 100 125

TEMPERATURE:Ta [℃]

LED short detection voltage: Vshort[mV]

Fig.14 LED Short detection

Threshold volta

Fig.13 LED open detection voltage

Temperature characteristic

VCC=12V VCC=12V

LEDR=2V

Technical Note

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BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Block diagram and pin configuration

Fig.15 Buck-boost application composition

●Pin layout ●Pin function table

BD8381EFV-M(HTSSOP-B28)

Fig.16

Pin Symbol Function

1 COMP Error amplifier output

2 SS Soft start

3 VCC Input power supply

4 EN Enable input

5 RT Oscillation frequency-setting resistance input

6 SYNC External synchronization signal input

7 GND Small-signal GND

8 THM Thermally sensitive resistor connection pin

9 FB ERRAMP FB signal input pin

10 DISC CR Timer discharge pin

11 VTH CR Timer threshold pin

12 DRLIN DRL switch terminal (Pulse output setting terminal)

13 FAIL1 Failure signal output

14 FAIL2 LED open/short detection signal output

15 OVP Over-voltage detection input

16 LEDC LED short detection pin (LED detection side)

17 LEDR LED short detection pin (Resistor detection side)

18 N.C. -

19 PGND PWM brightness source pin

20 PWMOUT PWM brightness signal output pin

21 CT GND short protection timer setting pin

22 OUTL Low-side external FET Gate Drive out put

23 DGND Low-side FET driver source pin

24 SW High-side FET Source pin

25 OUTH High-side external FET Gate Drive out put

26 CS DC/DC output current detection pin

27 BOOT High-side FET driver source pin

28 VREG Internal reference voltage output

DGND

COMP

ERR AMP

Vin

VCC

OVP

Control Logic

FAIL1VREG

DISC

GND

FAIL2

OCP OVP

OPEN/ SHORT/ SCP Detect

BOOT

PWM

VREG

OSC SLOPE

TIMER

Timer

Latch

Open Det

SCP Det

OCP

OVPTSDUVLO

Timer

Latch

PWM

DRV

CTL

SYNC

OUTH

OUTL

VREG

THM

VTH

VREG

COUT

LEDR

LEDC

PWMOUT

SHORT

Det

PGND

DRLIN

we; I a 1 ‘ ROM 20 k9 ‘ Rcr2 10 k9 4 Cor 100000 0F :1 (witﬁ mm M: (T mm mi r; , "m m m 3L1 FWWJWW wail

Technical Note

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BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●5V voltage reference (VREG)

5V (Typ.) is generated from the VCC input voltage when the enable pin is set high. This voltage is used to power internal

circuitry, as well as the voltage source for device pins that need to be fixed to a logical HIGH.

UVLO protection is integrated into the VREG pin. The voltage regulation circuitry operates uninterrupted for output

voltages higher than 4.5 V (Typ.), but if output voltage drops to 4.3 V (Typ.) or lower, UVLO engages and turns the IC off.

Connect a capacitor (Creg = 10µF Typ.) to the VREG terminal for phase compensation. Operation may become unstable if

Creg is not connected.

●About the method of setting the output current

ILED=min[THM / 5 V , 0.2V] / RISET [A]

As for min[THM / 5 V, 0.2V], small one is selected from among THM and VFB=0.2V.

Please input within the range of 0.25-5.0V when controlling the output current with THM. Please connect with VREG when

not using THM. There is a possibility that the LED GND short detection malfunctions when THM≦0.25V.

●About the method of setting the CR Timer

Built-in CR timer function enables PWM On Duty and frequency setting by external resistors and capacitors. (Refer to

equation below) Dimming range by the CR timer function are controllable to Dimming ratio 2%～45% and frequency range

1Hz～20kHz. (However, min pulse width are ≧ 25us)

Moreover PWM dimming is also feasible by external signal input to VTH pin to synchronize PWM control to external signal.

When using external signal, controllable range will be Dimming ratio 0%～100% and frequency 100Hz～20kHz.

(In case of using external PWM dimming, SCP(short circuit protection) will activate simultaneously to EN input. Therefore it

will detect SCP status in case duration between EN input time and PWM input time > SCP detection setting time.)

Fig. 17

○PWM timing chart with the external part

Fig.18

1.44

(RCR1+2RCR2)CCR

FPWM=

TON_PWM= RCR2

(RCR1+2RCR2) ×100

VTH

OUTL

ILED

Rcr1 20 kΩ

Rcr2 10 kΩ

100000 pF

2/3VREG

1/3VREG

GND

DRLIN

VTH

DISC

PWMOUT

SW ON

DRLIN signal is given priority.

①

②

③

④

①With EN injection, CCR is started to charge and VTH voltage rises.

②,③When VTH voltage rises to 2/3VREG, CCR is discharged by DISC until that

VTH terminal voltage falls to 1/3VREG.

While the voltage rises, PWMOUT outputs High, Conversely while the voltage falls,

PWMOUT outputs Low.

④When DRLIN=Hi, DRLIN signal prIority to VTH and PWMOUT outputs Hi.

BD8381EFV-M

VTH

DISC

Vref

RCR1

RCR2

CCR

(Vref:Constant voltage)

DRLIN

VREG

PWMOUT

Technical Note

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BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●About time from EN turning on to PWM turning on and the start from PWM low Duty

●About Dirating of the LED current that uses THM

It is an ability to set the Dirating curve of the LED current to the temperature as one of the functions to use THM. As for LED,

because deterioration at the high temperature is fast, the maximum allowance LED currents and the curve of temperatures

is given to the data sheet of LED. The voltage with a negative temperature characteristic in THM the Thermistor resistance

is used is input, and the LED current is controlled when the LED current is controlled according to the temperature

characteristic. Moreover, external Tr is used, and two input composition is also possible.

※The GND short protection detecting function (hereafter,

SCP) starts with EN=Low→Hi, and after the time of the

timer set with the external capacitor connected with CT, it

becomes latch off. (Above figure ① and ②)

The charge with SS begins synchronizing with turning on

EN. The PWM latch off function is built into when there is

not PWM turning on, and when the PWM latch off is

detected, (② of SS and the SCP counter) is reset. (The

time of the timer at latch OFF is calculated by oscillatory

frequency ×32770 counts of DC/DC. ) Therefore, the

following relations exist at time until PWM is turned on,

time of PWM latch timer and SCP detection time after EN

is turned on at external brightness.

(However, after ③ is turned on, ③ <④ is deleted from

the sequence because ④ doesn't operate. )

Each sequence

②＜④＜③⇒SCP is detected and No LED light.

④＜②＜③⇒LED lighting

④＜③＜②⇒LED lighting

PWM

COUP

OUTL

①SCP timer detection starts

②Time of SCP timer

③Time until turning on PWM

④Time of PWM latch timer ⑤Time until switching starts after inputting PWM

K i Fig.1?) RT versus switching frequency - External DC/DC converter oscillating frequency synchroniLat Do not sWitch from external to internal oscillation ol the DC/DC c on the SYNC pin. When the signal on the SYNC terminal is sw occurs before the internal oscillation circuitry starts to operate (on terminal is recognized). Moreover. the external synchronizing Si is used. And in the case of using external input frequency, followt - Soft Start Function The sott»start (SS) iimits the current and slows the rise-time of th prevention of the overshoot of the output voltage and the inrush overcurrent and the excess voltage is detected, and the switching TSS(soft-start time) is caicuiated below expression. Please rate application. TSS : 055 X 0.7V I SUA [5] C55: The capacit www rohm.com 8/23 @2012 ROHM 00., Ltd. Ail rights reserved.

Technical Note

8/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Buck-Boost DC/DC controller

・Over-voltage protection circuit (OVP)

The output of the DCDC converter should be connected to the OVP pin via a voltage divider. In determining an

appropriate trigger voltage of for OVP function, consider the total number of LEDs in series and the maximum variation in

VF. Also, bear in mind that over-current protection (OCP) is triggered at 0.85 x OVP trigger voltage. If the OVP

function engages, it will not release unless the DCDC voltage drops to 72.5% of the OVP trigger voltage. For example, if

ROVP1 (out put voltage side), ROVP2 (GND side), and DCDC voltage VOUT are conditions for OVP, then:

VOUT ≥ (ROVP1 + ROVP2) / ROVP2 x 2.0 V.

OVP will engage when VOUT ≧ 32 V if ROVP1 = 330 kΩ and ROVP2 = 22 kΩ.

・Buck-boost DC/DC converter oscillation frequency (FOSC)

The regulator’s internal triangular wave oscillation frequency can be set via a resistor connected to the RT pin (pin 5).

This resistor determines the charge/discharge current to the internal capacitor, thereby changing the oscillating frequency.

Refer to the following theoretical formula when setting RT:

fosc = x α [kHz]

60 x 106 (V/A/S) is a constant (±5%) determined by the internal circuitry, and α is a correction factor that varies in relation to RT:

{ RT: α = 100kΩ: 1.0, 150kΩ: 0.99, 200kΩ: 0.98, 280kΩ: 0.97 }

A resistor in the range of 100kΩ～280kΩ is recommended. Settings that deviate from the frequency range shown below

may cause switching to stop, and proper operation cannot be guaranteed.

Fig.19 RT versus switching frequency Fig.20 RT versus SYNC frequency

・External DC/DC converter oscillating frequency synchronization (FSYNC)

Do not switch from external to internal oscillation of the DC/DC converter if an external synchronization signal is present

on the SYNC pin. When the signal on the SYNC terminal is switched from high to low, a delay of about 30 µs (typ.)

occurs before the internal oscillation circuitry starts to operate (only the rising edge of the input clock signal on the SYNC

terminal is recognized). Moreover, the external synchronizing signal is given to priority when an external input frequency

is used. And in the case of using external input frequency, follow the Fig.14.

・Soft Start Function

The soft-start (SS) limits the current and slows the rise-time of the output voltage during the start-up, and hence leads to

prevention of the overshoot of the output voltage and the inrush current. The SS voltage is made Low when OVP of the

overcurrent and the excess voltage is detected, and the switching is stopped. Resume operation is begun.

TSS(soft-start time) is calculated below expression. Please refer to P.14-P.16 for the setting method by more detailed

application.

TSS = CSS×0.7V / 5uA [s] CSS: The capacitance at the SS-pin

60 × 106

RT [Ω]

150

DC/DC発振周波数[kHz]

RT抵抗値[kohm]

500

200

RT抵抗値[kohm]

SYNC入力周波数[kHz]

280

600

800

SYNC Frequency[KHz] RT resistance[KΩ]

DC/DC Fre

uenc

[KHz]

RT resistance[

Ω

]

FAlLi OPEN UVLO SHORT — ) rso ovp l—l R _{ DCF sop c i s EN=L°W — W" 9' Q UVLD/TSD EN=Low l— R UVLONSD - Operation of the Protection Circuitry - Under-Voltage Lock Out (UVLO) The UVLO shuts down all the circuits other than REG when VREG é 4.3V (TYP). - Thermal Shut Down (TSD) The TSD shuts down all the circuits other than REG when the T] reaches 175“C (TYF), and releases when the T] becomes below 15070 (TYP). - Over Current Protection (GDP) The GOP detects the current through the power-FET by monitoring the voltage of the high-side resistor, and activates when the CS voltage becomes less than VCC-O.6V (TYP). When the GOP is activated, the external capacitor ol the SS pin oecomes discharged and the switching operation of the DCDC turns ofl. - Over Voltage Protection (OVP) The output voltage ol the DCDC is detected with the OVP-pin voltage, and the protection activates when the OVF-pin voltage oecomes greater than 2.0V (TYP). When the OVF is activated. the external capacitor of the 88 pin becomes discharged and the switching operation of the DCDC turns ofl. - Short Circuit Protection (SOP) When the FB-pin voltage becomes less than 0.05V (TYP), the internal counter starts operating and latches ofl the circuit approximately aiter150ms (when CT : 0.1pF). ll the FB-pin voltage becomes over 0.05V belore 150ms. then the counter resets. When the LED anode (i.e. DCDC output voltage) is shorted to ground, then the LED current oecomes off and the FB-pin voltage becomes low. Furthermore, the LED current also becomes oli when the LED cathode is shorted to ground. Hence in summary, the SCP works with both cases of the LED anode and the cathode oeing shorted. LED GND short protection timer can calculate in the following expression. Tscp:Cct x 0.5vavp) I 5uA(TYP) x 8count (Tscp: LED GND short protection timer. Cct: capacitor connecter ol CT terminal) - LED Open Detection When the LED-pin voltage : 0.05V (TYP) as well as OVP-pin voltage 2 1.7V (TYP) simultaneously, the device detects as LED open and latches oil that particular channel. WWW ”hm“ . 9/23 2012.06 - Rev.c ©2012 ROHM 00,, Ltd. All rights reserved.

Technical Note

9/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

・Self-diagnostic functions

The operating status of the built-in protection circuitry is propagated to FAIL1 and FAIL2 pins (open-drain outputs). FAIL1

becomes low when UVLO, TSD, OVP, or SCP protection is engaged, whereas FAIL2 becomes low when open or short

LED is detected.

・Operation of the Protection Circuitry

・Under-Voltage Lock Out (UVLO)

The UVLO shuts down all the circuits other than REG when VREG ≦ 4.3V (TYP).

・Thermal Shut Down (TSD)

The TSD shuts down all the circuits other than REG when the Tj reaches 175℃ (TYP), and releases when the Tj

becomes below 150℃ (TYP).

・Over Current Protection (OCP)

The OCP detects the current through the power-FET by monitoring the voltage of the high-side resistor, and activates

when the CS voltage becomes less than VCC-0.6V (TYP).

When the OCP is activated, the external capacitor of the SS pin becomes discharged and the switching operation of

the DCDC turns off.

・Over Voltage Protection (OVP)

The output voltage of the DCDC is detected with the OVP-pin voltage, and the protection activates when the OVP-pin

voltage becomes greater than 2.0V (TYP).

When the OVP is activated, the external capacitor of the SS pin becomes discharged and the switching operation of

the DCDC turns off.

・Short Circuit Protection (SCP)

When the FB-pin voltage becomes less than 0.05V (TYP), the internal counter starts operating and latches off the circuit

approximately after 150ms (when CT = 0.1µF). If the FB-pin voltage becomes over 0.05V before 150ms, then the counter

resets. When the LED anode (i.e. DCDC output voltage) is shorted to ground, then the LED current becomes off and the

FB-pin voltage becomes low. Furthermore, the LED current also becomes off when the LED cathode is shorted to ground.

Hence in summary, the SCP works with both cases of the LED anode and the cathode being shorted.

LED GND short protection timer can calculate in the following expression.

Tscp=Cct×0.8V(TYP) / 5uA(TYP) ×8count

(Tscp: LED GND short protection timer, Cct: capacitor connecter of CT terminal)

・LED Open Detection

When the LED-pin voltage  0.05V (TYP) as well as OVP-pin voltage  1.7V (TYP) simultaneously, the device detects as

LED open and latches off that particular channel.

UVLO

TSD

OVP

OCP

Counter SCP

EN=Low

UVLO/TSD

FAIL1

OPEN

SHORT S

EN=Low

UVLO/TSD

FAIL2

MASK

Technical Note

10/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

・LED Short Detection

When the voltage between LEDR-pin and LEDC-pin  0.2 (TYP), the internal counter starts operating, and approximately

after 100ms (when FOSC = 300kHz) the operation latches off. With the PWM brightness control, the detecting operation

is processed only when PWMOUT-pin = High. If the condition of the detection operation is released before 100ms (when

FOSC = 300kHz), then the internal counter resets.

LED Short detection timer can calculate in the following expression.

Tshort=1 / FOSC × 32770count

(Tshort: LED short detection timer, FOSC: DC/DC Oscillation frequency.

There is a possibility that the LED short detection malfunctions when the difference of Vf is large. Therefore, please

adjust external resistance for connected Vf. It is recommended 1V-3V to the input range of LEDR and LEDC.

※The counter frequency is the DCDC switching frequency determined by the RT. The latch proceeds at the count of 32770.

○High luminance LED (multichip) with built-in LED of X piece in 1chip when using Y piece

Fig. 21

○When using the single chip

Fig. 22 Fig. 23

Setting method

R1：R2 = X：1

R3：R4 = ( X + 1 ) Y – 1：1

Setting method

R1：R2 = 1：1

R3：R4 = 2Y – 1：1

VOUT(DC/DC output）

Y piece

X piece

PWMOUT

LEDC

LEDR

VOUT(DC/DC output）

Y piece

PWMOUT

LEDC

LEDR

VOUT(DC/DC output）

Y piece

PWMOUT

LEDC

LEDR

Setting method

R3：R4 = Y – 1：1

○ When using the Low Vf LED

as Red LED, Orange color LED

Technical Note

11/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Error all condition

Protection Detecting Condition Operation after detect

[Detect] [Release]

UVLO VCC<4.3V VCC>4.5V

All blocks (but except REG)

shut down

TSD Tj>175℃ Tj<150℃ All blocks (but except REG)

shut down

OVP VOVP>2.0V VOVP<1.45V SS discharged

OCP VCS≦VCC-0.6V VCS>VCC-0.6V SS discharged

SCP VFB<0.05V

(150ms delay when CT=0.1µF) EN or UVLO Counter starts and then latches off

all blocks (but except REG)

LED open VFB<0.05V & VOVP>1.7V EN or UVLO Counter starts and then latches off

all blocks (but except REG)

LED short lVLEDR-VLEDCl>0.2V

(100ms delay when FOSC=300kHz) EN or UVLO Counter starts and then latches off

all blocks (but except REG)

●Protection sequence

Fig.24

Power supply turning on sequence

① Please turn on EN with Vcc≧4.5V or more after impressing Vcc.

② Please fix the potential of DRLIN and THM before turning on EN.

③ A soft start operates at the same time as turning on EN, and the switching is output.

④ After turning on VCC, the order is not related to other input when inputting external PWM from VTH.）

※It leads to the destruction of IC and external parts because it doesn't error output according to an external constant of

adjacent pin 24pin SW terminal, 25pin OUTH terminal, 26pin CS terminal and 27pin BOOT terminal.

Vcc

VREG

UVLO

THM

(Input by the

resistance division

of VREG. )

SYNC

DRLIN

OUTL

VOUT

4.5V

Release

①

②

Elm L

Technical Note

12/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Operation in error circumstances of LED

① LED open detection

Fig.25

②LED short detection

Fig.26

③ LED anode/cathode land GND short detection

Fig.27

VCC

OUTH

OUTL

PWMOUT

VOUT

OPEN

RSENSE

OUTH/OUTL

VOUT/OVP

FAIL2

LED OPEN

Switching Duty extends.

Switching stop

50m

V0V

1.7V

LED open detection when VOVP≧1.7 and VFB≦50mV

（When it achieves the detection condition, the FP latch is done. ）

VCC

OUTH

OUTL

PWMOUT

VOUT

LEDR

RSENSE

Short

VOUT

OUTH/OUTL

FAIL2

Switching stop

It detects short, and after the timer of △T,

error is detected with FAIL2.

LEDR-LEDC

It gets down by LED1 step.

0.2V

fosc

△T=32770×fosc

VCC

OUTH

OUTL

PWMOUT

VOUT

RSENSE

VOUT

OUTH/OUTL

FAIL2

Switching stop

It detects short, and after the timer of △T,

error is detected with FAIL2.

LED anode GND short

Short

to GND

200mV

50mV

Capacity dependence connected with CT

Timer operation of CT after GND

short detection.

FAIL1 becomes Hi? Low.

BD8381EFV—M Technical Note .Frocedure for exkernal componems selection Follow the steps as shown below lor seleclmg the exlernal componenls 1. Work out lLiMAX lrom me operarrng condmons < ____________="" feedback="" the="" vane="" 00="" l="" 2.="" se‘ect="" the="" vans="" 00="" r05="" such="" that="" \ocf=""> \LiMAX |||4 Voul , 3. Se‘ect me vamo or L such that 0,05[V/us] < l="" rcs="">< 03m="" us]="" -="" —="" —="" —="" 4.="" se‘ect="" cm‘="" schcﬂky="" dwodes="" mosfet="" and="" ros="" wmch="" meet="" with="" the="" rahngs="" 5.="" se‘ect="" me="" output="" capacumr="" which="" meers="" wrm="" the="" npple="" vonage="" roqorremems="" 6.="" se‘ect="" me="" mpm="" oaoaorro="" 7.="" work="" on="" wrm="" the="" compensahon="" orrcrm="" a.="" work="" on="" wrm="" the="" overrvohage="" prorecoon="" (ovp)="" semng="" www="" mm‘c‘m="" 13/23="" 2012.06="" -="" rev.c="" (c:="" 2012="" rohm="" cc...="" er.="" au="" ngms="" reserved.="">

Technical Note

13/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Procedure for external components selection

Follow the steps as shown below for selecting the external components

1. Work out IL_MAX from the operating conditions.

2. Select the value of RCS such that IOCP > IL_MAX

3. Select the value of L such that 0.05[V/µs] < L

Vout *RCS < 0.3[V/ µs]

4. Select coil, schottky diodes, MOSFET and RCS which meet with the ratings

5. Select the output capacitor which meets with the ripple voltage requirements

6. Select the input capacitor

7. Work on with the compensation circuit

8. Work on with the Over-Voltage Protection (OVP) setting

9. Work on with the soft-start setting

10. Verify experimentally

Feedback the value of L

%K ﬂjrﬁ % II

Technical Note

14/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

1. Computation of the Input Peak Current and IL_MAX

①Calculation of the maximum output voltage (Vout_max)

To calculate the Vout_max, it is necessary to take into account of the VF variation and the number of LED connection in

series.

Vout_max = (VF + ΔVF) × N + 0.2+ RPWMON×Iout ΔVF: VF Variation N: Number of LED connection in series

RPWMON: PWMOUT FET Ron

②Calculation of the output current Iout

D: FB standard voltage variation

M: Output current resistance variation

③Calculation of the input peak current IL_MAX

IL_MAX = IL_AVG + 1/2ΔIL

IL_AVG = (VIN + Vout) × Iout / (n × VIN)

ΔIL= × × n: efficiency Fosc: switching frequency

・The worst case scenario for VIN is when it is at the minimum, and thus the minimum value should be applied in the

equation.

・The L value of 6.8µH  33µH is recommended. The current-mode type of DC/DC conversion is adopted for

BD8381EFV-M, which is optimized with the use of the recommended L value in the design stage. This recommendation

is based upon the efficiency as well as the stability. The L values outside this recommended range may cause irregular

switching waveform and hence deteriorate stable operation.

・n (efficiency) is approximately 80%

Fig.28 External Application Circuit

2. The setting of over-current protection

Choose Rcs with the use of the equation Vocp_min (=0.52V) / Rcs > IL_MAX

When investigating the margin, it is worth noting that the L value may vary by approximately ±30%.

3. The selection of the L

In order to achieve stable operation of the current-mode DC/DC converter, we recommend selecting the L value in the

range indicated below:

0.05 [V/µs] < < 0.3 [V/µs]

The smaller allows stability improvement but slows down the response time.

4. Selection of coil L, diode D1 and D2, MOSFET M1 and M2, and Rcs

Current rating Voltage rating Heat loss

Coil L > IL_MAX ―

Diode D1 > Iocp > VIN_MAX

Diode D2 > Iocp > Vout

MOSFET M1 > Iocp > VIN_MAX

MOSFET M2 > Iocp > Vout

Rcs ― ― > Iocp2 × Rcs

※ Allow some margin, such as the tolerance of the external components, when selecting.

※ In order to achieve fast switching, choose the MOSFETs with the smaller gate-capacitance.

VIN

Fosc

Vout

VIN+Vout

Vout×Rcs

VIN

Rcs

LD2

Vout

Vout×Rcs

Iout= 0.2V×D

RISET

Technical Note

15/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

5. Selection of the output capacitor

Select the output capacitor Cout based on the requirement of the ripple voltage Vpp.

Vpp = × × + I

L_MIN × RESR

Choose Cout that allows the Vpp to settle within the requirement. Allow some margin also, such as the tolerance of the

external components.

6.Selection of the input capacitor

A capacitor at the input is also required as the peak current flows between the input and the output in DC/DC conversion.

We recommend an input capacitor greater than 10µF with the ESR smaller than 100m. The input capacitor outside of

our recommendation may cause large ripple voltage at the input and hence lead to malfunction.

7. Phase Compensation Guidelines

In general, the negative feedback loop is stable when the following condition is met:

 Overall gain of 1 (0dB) with a phase lag of less than 150º (i.e., a phase margin of 30º or more)

However, as the DC/DC converter constantly samples the switching frequency, the gain-bandwidth (GBW) product of the

entire series should be set to 1/10 the switching frequency of the system. Therefore, the overall stability characteristics

of the application are as follows:

 Overall gain of 1 (0dB) with a phase lag of less than 150º (i.e., a phase margin of 30º or more)

 GBW (frequency at gain 0dB) of 1/10 the switching frequency

Thus, to improve response within the GBW product limits, the switching frequency must be increased.

The key for achieving stability is to place fz near to the GBW. GBW is decided by phase delay fp1 by COUT and output

impedance RL. Of each becomes like the next expression.

Phase-lead fz = [Hz]

Phase-lag fp1 = [Hz]

Good stability would be obtained when the fz is set between 1kHz～10kHz.

Please substitute the value at the maximum load for RL.

In buck-boost applications, Right-Hand-Plane (RHP) Zero exists. This Zero has no gain but a pole characteristic in terms

of phase. As this Zero would cause instability when it is in the control loop, so it is necessary to bring this zero before the

GBW.

fRHP= [Hz] I

LOAD: MAXIMUM LOAD CURRENT

It is important to keep in mind that these are very loose guidelines, and adjustments may have to be made to ensure

stability in the actual circuitry. It is also important to note that stability characteristics can change greatly depending on

factors such as substrate layout and load conditions. Therefore, when designing for mass-production, stability should be

thoroughly investigated and confirmed in the actual physical design.

Iout

Cout

Vout

Vout+VIN

Fosc

2πCpcRpc

COMP

Vout

Rpc

LED

Cpc

2πRLCout

2πILOADL

Vout+VIN/(Vout+VIN)

Technical Note

16/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

8. Setting of the soft-start

The soft-start allows minimization of the coil current as well as the overshoot of the output voltage at the start-up.

For the capacitance we recommend in the range of 0.001  0.1µF. For the capacitance less than 0.001µF may cause

overshoot of the output voltage. For the capacitance greater than 0.1µF may cause massive reverse current through the

parasitic elements of the IC and damage the whole device. In case it is necessary to use the capacitance greater than

0.1µF, ensure to have a reverse current protection diode at the Vcc or a bypass diode placed between the SS-pin and the

Vcc.

Soft-start time TSS

TSS = CSSX0.7V / 5uA [s] CSS: The capacitance at the SS-pin

9. Verification of the operation by taking measurements

The overall characteristic may change by load current, input voltage, output voltage, inductance, load capacitance,

switching frequency, and the PCB layout. We strongly recommend verifying your design by taking the actual

measurements.

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Technical Note

17/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0 25 50 75 100 125 150

Power dissipation Pd [W]

Temp Ta [℃]

(1)θja=26.6℃/W(4 layer board, and area of cupper foil is 89%)

(2)θja=37.9℃/W(2 layer board, and area of cupper foil is 89%)

(3)θja=67.6℃/W(2 layer board, and area of cupper foil is 4.6%)

(3)1.85W

(1)4.70W

(2)3.30W

●Power consumption calculation

Pc(N) = ICC*VCC + 2

1*Ciss*VREG*Fsw*VREG×2×2+ 2

1×Ciss×VREG×FPWM×VREG×2

ICC ： Current of the maximum circuit

VCC ：Power-supply voltage

Ciss ： External FET capacity

Vsw ： SW gate voltage

Fsw ： SW frequency

FPWM ： PWM frequency

＜Calculation example＞

When assuming

Pc(4) = 7mA × 30V + 500pF × 5V × 300kHz × 5V×2×2+ 2

1×1500pF×5×200×5×2,

it becomes

Pc = about 210mW.

Fig.29

Note1: The value of Power consumption : on glass epoxy board measuring 70mm×70mm×1.6mm

(1 layer board/Copper foil thickness 18µm)

Note2: The value changes depending on the density of the board copper foil.

However, this value is an actual measurement value and no guarantee value.

HTSSOP-B28

Pd=1.85W (0.37W)： Board copper foil area 225m ㎡

Pd=3.30W (0.66W)： Board copper foil area 4900m ㎡

Pd=4.70W (0.94W)： Board copper foil area 4900m ㎡

Technical Note

18/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Application circuit 1

DGND

COMP

ERR AMP

Vin

VCC

OVP

Control Logic

FAIL1VREG

DISC

GND

FAIL2

OCP OVP

OPEN/ SHORT/ SCP Detect

BOOT

PWM

VREG

OSC SLOPE

TIMER

Timer

Latch

Open Det

SCP Det

OCP

OVPTSDUVLO

Timer

Latch

PWM

DRV

CTL

SYNC

OUTH

OUTL

VREG

THM

VTH

VREG

COUT

LEDR

LEDC

PWMOUT

SHORT

Det

PGND

DRLIN

INP2INP1

Fig. 30

Buck application composition (It is INP1, INP2, and two input selector function. )

●Application circuit 2

DGND

COMP

ERR AMP

Vin

VCC

OVP

Control Logic

FAIL1VREG

DISC

GND

FAIL2

OCP OVP

OPEN/ SHORT/ SCP Detect

BOOT

PWM

VREG

OSC SLOPE

TIMER

Timer

Latch

Open Det

SCP Det

OCP

OVPTSDUVLO

Timer

Latch

PWM

DRV

CTL

SYNC

OUTH

OUTL

VREG

THM

VTH

VREG

COUT

LEDR

LEDC

PWMOUT

SHORT

Det

PGND

DRLIN

VREG

30kO

20kO

Fig. 31

Boost application composition (When invalidating short detection. )

Technical Note

19/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Reference PCB Setting

COMP

VCC

SYNC

GND

THM

DISC

VTH

DRLIN

FAIL1

FAIL2

VREG

BOOT

OUTH

DGND

OUTL

PWMOUT

PGND

N.C.

LEDR

LEDC

OVP

CVCC3

RPCCPC

CSS

SW1

GND RRT

SYNC

VREG

RTHM11RTHM21

THM1

THM2

RTHM3

CCRRCR2RCR1

VTH

SW2

RFL1

RFL2

VREG

FAIL1 FAIL2

LEDC

LEDR

PGND

CCT

ROUTL

RSW2

DGND

RSW1

CBOOT

RQ1

DI2

COUT1

COUT2

ROVP1ROVP2

RLEDR1RLEDR2

VOUT

LEDOUT

RQ3

RSENSE1

RSENSE2

RCS3

CCS

RCS1

RCS2

CREG

VREG

VCC

CVCC1

CVCC2

No. Component

Name Component Value Product Name No. Componen

t Name Component Value Product Name

1 CVCC1 10uF

GCM32ER71E106KA42

23 CCS N.M -

2 CVCC2 10uF

GCM32ER71E106KA42

24 CBOOT 0.1uF

GCM188R11H104KA42

3 CVCC3 0.1uF

GRM31CB31E104KA75B

25 Q1 RSS070N05 -

4CPC 0.1uF

GCM188R11H104KA42

26 DI1 RB050L-40 -

5 RPC 820ohm

MCR03 Series

27 RSW1 0ohm -

6CSS 0.1uF

GCM188R11H104KA42

28 RSW2 N.M -

7 RRT 200kohm

MCR03 Series

29 RQ1 N.M -

8 RTHM11 100kohm

MCR03 Series

30 L

10uH

SLF12575T100M5R4-H

9 RTHM12 100kohm

MCR03 Series

31 ROUTL 0ohm

MCR03 Series

10 RTHM21 100kohm

MCR03 Series

32 Q2 RSS070N05 -

11 RTHM22 100kohm

MCR03 Series

33 DI2 RF201L2S -

12 RTHM3 0ohm

34 COUT1 10uF

GCM32ER71E106KA42

13 TR - - 35 COUT2 10uF

GCM32ER71E106KA42

14 RCR1 30kohm

MCR03 Series

36 CCT 0.1uF

GCM188R11H104KA42

15 RCR2 10kohm

MCR03 Series

37 ROVP1 270kohm

MCR03 Series

16 CCR 0.22uF

GCM21BR11H224KA01

38 ROVP2 30kohm

MCR03 Series

17 FRL1 100kohm

MCR03 Series

39 RLEDR1 90kohm

MCR03 Series

18 FRL2 100kohm

MCR03 Series

39 RLEDR2 30kohm

MCR03 Series

19 CREG 10uF

GCM32ER71E106KA42

40 Q3 RSS070N05 -

20 RCS1 110mohm

MCR100JZHFSR110

41 RQ3 N.M -

21 RCS2 N.M - 42 RSENSE1 200mohm

MCR100JZHFSR510

22 RCS3 0ohm - 43 RSENSE2 N.M

※When no PWM dimming, DI2 should be schottky diode instead of Fast Recovery diode to improve efficiency. Remove Q3, change RQ3=0Ω

then short to DS.

When dimming with External PWM signal, DISC should be pulled up to VREG with 10KΩ,then input PWM signal to VTH.

(when no PWM dimming, remove Q3, change RQ3=0Ωand short to DS）

Wig??? aﬂﬁﬂ

Technical Note

20/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Input/output Equivalent Circuits

1. COMP 2. SS 4. EN

5. RT 6. SYNC 8. THM

9. FB 10. DISC 11. VTH

12. DRLIN

VREG VCC

VREG

VREG VREG

SYNC

VCC

VREG

DISC

VREG

VTH

OVP

VREG VREG

COMP

15. OVP13,14. FAIL1,FAIL2

DRLIN

VREG

FAIL1

FAIL2

VCC

※The values are all Typ. value.

Technical Note

21/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Input/output Equivalent Circuits(Continuation)

20. CT

24. SW 25. OUTH 26. CS

27. BOOT

VREG

VCC

BOOT BOOT

SW SW SW

OUTH

VREG

BOOT

16,17. LEDC, LEDR

LEDC

LEDR

19,22. PWMOUT, OUTL

28. VREG

VREG VCC

VREG

VREG VREG

※The values are all Typ. value.

Technical Note

22/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Notes for use

1. Absolute maximum ratings

We are careful enough for quality control about this IC. So, there is no problem under normal operation, excluding that it

exceeds the absolute maximum ratings. However, this IC might be destroyed when the absolute maximum ratings, such

as impressed voltages or the operating temperature range(Topr), is exceeded, and whether the destruction is short circuit

mode or open circuit mode cannot be specified. Please take into consideration the physical countermeasures for safety,

such as fusing, if a particular mode that exceeds the absolute maximum rating is assumed.

2. Reverse polarity connection

Connecting the power line to the IC in reverse polarity (from that recommended) will damage the part. Please utilize the

direction protection device as a diode in the supply line.

3. Power supply line

Due to return of regenerative current by reverse electromotive force, using electrolytic and ceramic suppress filter capacitors

(0.1µF) close to the IC power input terminals (Vcc and GND) are recommended. Please note the electrolytic capacitor value

decreases at lower temperatures and examine to dispense physical measures for safety. And, for ICs with more than one

power supply, it is possible that rush current may flow instantaneously due to the internal powering sequence and delays.

Therefore, give special consideration to power coupling capacitance, width of power wiring, GND wiring, and routing of

wiring. Please make the power supply lines (where large current flow) wide enough to reduce the resistance of the power

supply patterns, because the resistance of power supply pattern might influence the usual operation.

4. GND line

The ground line is where the lowest potential and transient voltages are connected to the IC.

5. Thermal design

Do not exceed the power dissipation (Pd) of the package specification rating under actual operation, and please design

enough temperature margins.

6. Short circuit mode between terminals and wrong mounting

Do not mount the IC in the wrong direction and be careful about the reverse-connection of the power connector.

Moreover, this IC might be destroyed when the dust short the terminals between them or power supply, GND.

7. Radiation

Strong electromagnetic radiation can cause operation failures.

8. ASO(Area of Safety Operation.)

Do not exceed the maximum ASO and the absolute maximum ratings of the output driver.

9. TSD(Thermal shut-down)

The TSD is activated when the junction temperature (Tj) reaches 175℃(with 25℃ hysteresis), and the output terminal is

switched to Hi-z. The TSD circuit aims to intercept IC from high temperature. The guarantee and protection of IC are not purpose.

Therefore, please do not use this IC after TSD circuit operates, nor use it for assumption that operates the TSD circuit.

10. Inspection by the set circuit board

The stress might hang to IC by connecting the capacitor to the terminal with low impedance. Then, please discharge

electricity in each and all process. Moreover, in the inspection process, please turn off the power before mounting the IC,

and turn on after mounting the IC. In addition, please take into consideration the countermeasures for electrostatic

damage, such as giving the earth in assembly process, transportation or preservation.

11. IC terminal input

This IC is a monolithic IC, and has P+ isolation and P substrate for the element separation. Therefore, a parasitic PN

junction is firmed in this P-layer and N-layer of each element. For instance, the resistor or the transistor is connected to

the terminal as shown in the figure below. When the GND voltage potential is greater than the voltage potential at

Terminals A or B, the PN junction operates as a parasitic diode. In addition, the parasitic NPN transistor is formed in said

parasitic diode and the N layer of surrounding elements close to said parasitic diode. These parasitic elements are

formed in the IC because of the voltage relation. The parasitic element operating causes the wrong operation and

destruction. Therefore, please be careful so as not to operate the parasitic elements by impressing to input terminals

lower voltage than GND(P substrate). Please do not apply the voltage to the input terminal when the power-supply

voltage is not impressed. Moreover, please impress each input terminal lower than the power-supply voltage or equal to

the specified range in the guaranteed voltage when the power-supply voltage is impressing.

structure of IC

12. Earth wiring pattern

Use separate ground lines for control signals and high current power driver outputs. Because these high current outputs

that flows to the wire impedance changes the GND voltage for control signal. Therefore, each ground terminal of IC must

be connected at the one point on the set circuit board. As for GND of external parts, it is similar to the above-mentioned

Terminal-A

Parasitic

element GND

P+P

Terminal-A

Terminal-B

GND

P-Substrate

GND

Surrounding

elements

Resistor Transistor(NPN)

P+P+P+

P-Substrate

Parasitic

element

Parasitic

element

Parasitic

element

Terminal-B

OOOOOOOOOOOOOOOO 5% 9:6

Technical Note

23/23

BD8381EFV-M

www.rohm.com 2012.06 - Rev.C

●Ordering part number

B D 8 3 8 1 E F V - M E 2

Part No. Part No.

Package

EFV: HTSSOP-B28 for

Automotive Packaging and forming specification

E2: Embossed tape and reel

∗

Order quantity needs to be multiple of the minimum quantity.

Embossed carrier tape (with dry pack)Tape

Quantity

Direction

of feed

The direction is the 1pin of product is at the upper left when you hold

reel on the left hand and you pull out the tape on the right hand

2500pcs

()

Direction of feed

Reel 1pin

(Unit : mm)

HTSSOP-B28

0.08

0.08 S

1.0±0.2

0.5±0.15

−

0.17 +0.05

0.03

1528

141

(2.9)

4.4±0.1

(5.5)

(MAX 10.05 include BURR)

0.625

6.4±0.2

9.7±0.1

1PIN MARK

1.0MAX

0.65

0.85±0.05

0.08±0.05

0.24 +0.05

0.04

Datasheet

Notice - SS Rev.002

Notice

Precaution on using ROHM Products

1. If you intend to use our Products in devices requiring extremely high reliability (such as medical equipment (Note 1),

aircraft/spacecraft, nuclear power controllers, etc.) and whose malfunction or failure may cause loss of human life,

bodily injury or serious damage to property (“Specific Applications”), please consult with the ROHM sales

representative in advance. Unless otherwise agreed in writing by ROHM in advance, ROHM shall not be in any way

responsible or liable for any damages, expenses or losses incurred by you or third parties arising from the use of any

ROHM’s Products for Specific Applications.

(Note1) Medical Equipment Classification of the Specific Applications

JAPAN USA EU CHINA

CLASSⅢ CLASSⅢ CLASSⅡb CLASSⅢ

CLASSⅣ CLASSⅢ

2. ROHM designs and manufactures its Products subject to strict quality control system. However, semiconductor

products can fail or malfunction at a certain rate. Please be sure to implement, at your own responsibilities, adequate

safety measures including but not limited to fail-safe design against the physical injury, damage to any property, which

a failure or malfunction of our Products may cause. The following are examples of safety measures:

[a] Installation of protection circuits or other protective devices to improve system safety

[b] Installation of redundant circuits to reduce the impact of single or multiple circuit failure

3. Our Products are not designed under any special or extraordinary environments or conditions, as exemplified below.

Accordingly, ROHM shall not be in any way responsible or liable for any damages, expenses or losses arising from the

use of any ROHM’s Products under any special or extraordinary environments or conditions. If you intend to use our

Products under any special or extraordinary environments or conditions (as exemplified below), your independent

verification and confirmation of product performance, reliability, etc, prior to use, must be necessary:

[a] Use of our Products in any types of liquid, including water, oils, chemicals, and organic solvents

[b] Use of our Products outdoors or in places where the Products are exposed to direct sunlight or dust

[c] Use of our Products in places where the Products are exposed to sea wind or corrosive gases, including Cl2,

H2S, NH3, SO2, and NO2

[d] Use of our Products in places where the Products are exposed to static electricity or electromagnetic waves

[e] Use of our Products in proximity to heat-producing components, plastic cords, or other flammable items

[f] Sealing or coating our Products with resin or other coating materials

[g] Use of our Products without cleaning residue of flux (even if you use no-clean type fluxes, cleaning residue of

flux is recommended); or Washing our Products by using water or water-soluble cleaning agents for cleaning

residue after soldering

[h] Use of the Products in places subject to dew condensation

4. The Products are not subject to radiation-proof design.

5. Please verify and confirm characteristics of the final or mounted products in using the Products.

6. In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse. is applied,

confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power

exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect

product performance and reliability.

7. De-rate Power Dissipation (Pd) depending on Ambient temperature (Ta). When used in sealed area, confirm the actual

ambient temperature.

8. Confirm that operation temperature is within the specified range described in the product specification.

9. ROHM shall not be in any way responsible or liable for failure induced under deviant condition from what is defined in

this document.

Precaution for Mounting / Circuit board design

1. When a highly active halogenous (chlorine, bromine, etc.) flux is used, the residue of flux may negatively affect product

performance and reliability.

2. In principle, the reflow soldering method must be used; if flow soldering method is preferred, please consult with the

ROHM representative in advance.

For details, please refer to ROHM Mounting specification

Datasheet

Notice - SS Rev.002

Precautions Regarding Application Examples and External Circuits

1. If change is made to the constant of an external circuit, please allow a sufficient margin considering variations of the

characteristics of the Products and external components, including transient characteristics, as well as static

characteristics.

2. You agree that application notes, reference designs, and associated data and information contained in this document

are presented only as guidance for Products use. Therefore, in case you use such information, you are solely

responsible for it and you must exercise your own independent verification and judgment in the use of such information

contained in this document. ROHM shall not be in any way responsible or liable for any damages, expenses or losses

incurred by you or third parties arising from the use of such information.

Precaution for Electrostatic

This Product is electrostatic sensitive product, which may be damaged due to electrostatic discharge. Please take proper

caution in your manufacturing process and storage so that voltage exceeding the Products maximum rating will not be

applied to Products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron,

isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control).

Precaution for Storage / Transportation

1. Product performance and soldered connections may deteriorate if the Products are stored in the places where:

[a] the Products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2

[b] the temperature or humidity exceeds those recommended by ROHM

[c] the Products are exposed to direct sunshine or condensation

[d] the Products are exposed to high Electrostatic

2. Even under ROHM recommended storage condition, solderability of products out of recommended storage time period

may be degraded. It is strongly recommended to confirm solderability before using Products of which storage time is

exceeding the recommended storage time period.

3. Store / transport cartons in the correct direction, which is indicated on a carton with a symbol. Otherwise bent leads

may occur due to excessive stress applied when dropping of a carton.

4. Use Products within the specified time after opening a humidity barrier bag. Baking is required before using Products of

which storage time is exceeding the recommended storage time period.

Precaution for Product Label

QR code printed on ROHM Products label is for ROHM’s internal use only.

Precaution for Disposition

When disposing Products please dispose them properly using an authorized industry waste company.

Precaution for Foreign Exchange and Foreign Trade act

Since our Products might fall under controlled goods prescribed by the applicable foreign exchange and foreign trade act,

please consult with ROHM representative in case of export.

Precaution Regarding Intellectual Property Rights

1. All information and data including but not limited to application example contained in this document is for reference

only. ROHM does not warrant that foregoing information or data will not infringe any intellectual property rights or any

other rights of any third party regarding such information or data. ROHM shall not be in any way responsible or liable

for infringement of any intellectual property rights or other damages arising from use of such information or data.:

2. No license, expressly or implied, is granted hereby under any intellectual property rights or other rights of ROHM or any

third parties with respect to the information contained in this document.

Other Precaution

1. This document may not be reprinted or reproduced, in whole or in part, without prior written consent of ROHM.

2. The Products may not be disassembled, converted, modified, reproduced or otherwise changed without prior written

consent of ROHM.

3. In no event shall you use in any way whatsoever the Products and the related technical information contained in the

Products or this document for any military purposes, including but not limited to, the development of mass-destruction

weapons.

4. The proper names of companies or products described in this document are trademarks or registered trademarks of

ROHM, its affiliated companies or third parties.

DatasheetDatasheet

Notice – WE Rev.001

General Precaution

1. Before you use our Pro ducts, you are requested to care fully read this document and fully understand its contents.

ROHM shall n ot be in an y way responsible or liabl e for fa ilure, malfunction or acci dent arising from the use of a ny

ROHM’s Products against warning, caution or note contained in this document.

2. All information contained in this docume nt is current as of the issuing date and subj ect to change without any prior

notice. Before purchasing or using ROHM’s Products, please confirm the la test information with a ROHM sale s

representative.

3. The information contained in this doc ument is provi ded on an “as is” basis and ROHM does not warrant that all

information contained in this document is accurate an d/or error-free. ROHM shall not be in an y way responsible or

liable for any damages, expenses or losses incurred by you or third parties resulting from inaccur acy or errors of or

concerning such information.

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