The ADP130 is a post regulation device which offers a unique architecture. It has an additional bias pin connected to battery voltage. This allows the device to operate with lower headroom (ie difference between Vout and Vin) while offering excellent PSRR. The figure above shows a circuit using the ADP130 with the ADP2108 DC/DC device. The left hand graph shows the ripple rejection when the DC/DC regulator is in the PWM mode, while the right hand graph shows the LDO output in the presence of a PFM mode DC/DC converter. The LDO rejects the switching noise of the DC-DC device effectively.