Supply Sequencer

It is often the case with electrical systems using more than one power supply that the supplies must be switched on in a defined sequence to avoid electrical damage that may otherwise occur. The MAX6820 chip from Maxim (http://pdfserv. maxim-ic.com/arpdf/MAX6819-MAX6820.pdf) contains all the necessary control circuitry to perform this function in one package. The chip samples the primary supply VCC1 at its input SETV (pin 3) via the potential divider formed by R1 and R2.