MAX6819

The MAX6819/MAX6820 are power-supply sequencers or dual-voltage microprocessors (Ps) and multivoltage ystems. These devices monitor a primary supply oltage and enable/disable an external N-channel OSFET switch for a secondary supply voltage. The AX6819/MAX6820 control local component voltage equencing when system power-on/power-off characteristics annot be guaranteed (supplies come from a ultivoltage system bus, silver box, or must be equenced in different modes for components on the ame board). These small power-supply sequencers mprove system reliability.

The MAX6819/MAX6820 include an internal voltage reference/ omparator with externally adjustable thresholds o monitor the primary power supply. When the rimary supply is below the desired threshold, an external econdary supply MOSFET switch is disabled.

hen the primary supply exceeds the threshold, an nternal charge pump is activated and the external OSFET switch is enabled to connect the secondary upply to the load. The charge pump fully enhances the -channel MOSFET switch to provide a very low RDSON oltage drop. The devices can be connected to upport various supply sequencing priorities such as I/O before VCORE or VCORE before VI/O.

The MAX6819 features a logic-driven EN input to nable/disable the external MOSFET drive and includes n internally fixed 200ms enable timeout period VPRIMARY GOOD to VSECONDARY ENABLE). The AX6820 allows the enable timeout period to be djusted with a single external capacitor. Both devices re specified over the automotive temperature range -40 to +125) and are available in space-saving -pin SOT23 packages.