Description

The PMP4494 is a 5V to 3.3V 1.2A DC-DC converter with a Vout hold-up circuit. The synchronous buck converter LM20242 is used in the design to provide high efficiency for the system voltage. A boost converter TPS61170 boosts an auxiliary rail from 10V up to 20V to provide the backup voltage. A supply voltage supervisor TLV809 monitors the system voltage and switches the supply to the backup voltage once the system voltage falls below the threshold voltage. Along with the boost circuit, the hold-up capacitance is significantly reduced while still meeting the 200mS hold-up time specification.