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Microprocessor supervisory circuit monitors system voltage with programmable delay

A family of microprocessor supervisory circuits has been designed to monitor system voltages from 0.4V to 5.0V.

Diodes Incorporated's PT7M3808 is said to have a threshold accuracy from 0.5% and an adjustable delay time from 1.25ms to 10ms, enabling power-on reset functionality for microprocessor and other digital systems, while consuming minimal power.

The circuit is offered in fixed-threshold versions for standard voltage rails between 0.9V and 5V, Diodes explains, and includes an adjustable threshold version down to 0.4V. The PT7M3808 is designed to use 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 said to be adjusted from 1.25ms to 10ms by connecting an external capacitor to the CT pin. A longer 20ms and 300ms delay are apparently possible. This is achieved by disconnecting the CT pin for a 20ms result, or connecting the CT pin to VDD with a resistor for 300ms.

Diodes says that its PT7M3808 has a very low quiescent current, typically 2.8uA, which it explains makes it well-suited for battery-powered applications.

Available in SOT26 and DFN2020-6 packages, Diodes concludes that its PT7M3808 takes up little board space for both new and drop-in replacement designs.

Author
Bethan Grylls

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