Microprocessor supervisory circuit monitors system voltage with programmable delay

The PT7M3808 family of microprocessor supervisory circuits introduced from Diodes Incorporated monitors system voltages from 0.4V to 5V. With threshold accuracy from 0.5% and an adjustable delay time from 1.25ms to 10ms, these small form-factor devices enable power-on reset functionality for MPUs and other digital systems while using minimal power. Applications include desktop and notebook computers, and battery-powered portable equipment for businesses ranging from data centres to security systems. Offered in fixed-threshold versions for standard voltage rails between 0.9V and 5V, and with an adjustable threshold version down to 0.4V, the device employs 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 5V. The delay time is adjusted from 1.25ms to 10ms by joining an external capacitor to the CT pin; a longer 20ms delay can be accomplished by disconnecting the CT pin, while a 300ms delay is plausible by connecting the CT pin to VDD with a resistor. The device has a very low quiescent current, typically 2.8A, making it ideal for battery-powered applications. Available in SOT26 and DFN2020-6 packages, the device takes up very little board space for both new and drop-in replacement designs.