
Supervisory circuit monitors system voltage with programmable delay
The PT7M3808 devices enable power-on reset functionality for microprocessor and other digital systems while consuming minimal power. Applications include notebook and desktop computers, and battery-powered portable equipment for markets ranging from data centers to security systems.
With a fixed-threshold versions for standard voltage rails between 0.9V and 5V, and with an adjustable threshold version down to 0.4V, the PT7M3808 uses a precision reference to provide a 0.5% negative-going input threshold accuracy when monitoring voltages up to 3.3V and 1% accuracy at voltages from 3.3V to 5.0V. The delay time is adjusted from 1.25ms to 10ms by connecting an external capacitor to the CT pin; a longer 20ms delay can be achieved by disconnecting the CT pin, while a 300ms delay is possible by connecting the CT pin to VDD with a resistor. It has a low quiescent current, typically 2.8μA, for battery-powered applications .
The PT7M3808 family supervisory ICs are priced at $0.60 each in 1,000 piece quantities and are available in SOT26 and DFN2020-6 packages.
