FET Drive Simple ADM6819 ADM6820

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Apr 6, 2015
FET Drive Simple Sequencers ADM6819/ADM6820

The ADM6819 and ADM6820 are simple power supply sequencers with FET drive capability for enhancing N-channel MOSFETs. These devices can monitor a primary supply voltage and enable/disable an external N-channel FET for a secondary supply. The ADM6819 has the ability to monitor two supplies. When more than two voltages require sequencing, multiple ADM6819/ADM6820 devices can be cascaded to achieve this. The devices operate over a supply range of 2.95 V to 5.5 V.
An internal comparator monitors the primary supply using the VSET pin. The input to this comparator is externally set via a resistor divider from the primary supply. When the voltage at the VSET pin rises above the comparator threshold, an internal charge pump on the GATE output enhances the secondary supply FET.
The ADM6819 features an enable (EN) pin that is fed to the input of an additional comparator and reference circuit. This pin can be used as a digital enable or a secondary power good comparator to monitor a second supply and enables the GATE only if both supplies are valid. When both inputs of the internal comparators are above the threshold, a fixed 300 ms timeout occurs before the GATE is driven high and the secondary supply is enabled.
The ADM6820 has only one comparator that is on the SETV pin. It also features a timeout period that is adjustable via a single external capacitor on the SETD pin.
The ADM6819/ADM6820 are packaged in small 6-lead SOT-23 packages.

Single chip enables power supply sequencing of two supplies On-board charge pump fully enhances N-channel FET Adjustable primary supply monitor to 0.618 V Delay from primary supply to secondary supply enabled
Fixed 300 ms delay (ADM6819) Capacitor adjustable delay (ADM6820) Logic/analog driven enable input (ADM6819) 40°C to +85°C operating range Packaged in small 6-lead SOT-23 package Pin-to-pin compatibility with MAX6819/MAX6820.

- Multivoltage systems
-Dual voltage microprocessors/FPGAs/ASICs/DSPs
- Network processors
-Telecom and datacom systems
-PC/server applications

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.

Functional Schematic GaAs DPDT Diversity Switch MASWSS0175
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