LOW QUIESCENT CURRENT PROGRAMMABLE-DELAY SUPERVISORY CIRCUIT

DESCRIPTION

The 84NXX can monitor and provide reset function for

system voltages from 0.4V which is the microprocessor

supervisory circuit. If the SENSE voltage falls below its

threshold (VIT), the voltage of manual reset ( MR ) is pulled to a

logic low, the RESET signal will be asserted. The reset voltage

can be factory-set from 0.9V to 5V, while the 84NXX reset

voltage is adjustable with an external resistor divider. When

SENSE voltage and MR exceed their thresholds, RESET is

driven to a logic high after a user-programmable delay time.

The 84NXX has a very low quiescent, which makes it ideal

suitable for battery-powered applications. It provides a precision

reference to achieve ±1% threshold accuracy. A capacitor is

connected between CDELAY and GND which determined reset

delay time, allowing the user to select any delay time from

2.1ms to 10s. When the CDELAY pin connected to VCC, the delay

time is selected 380ms ,while leaving the CDELAY pin float, the

delay time is selected 24ms.

FEATURES

* Standard Voltage Rails From 0.9V to 5V and Adjustable Voltage From 0.4V are Available

* Low Quiescent Current: 1.6uA (typ.)

* Delay Time: 2.1ms to 10s

* High Threshold Accuracy: ±1% (typ.)

* Manual Reset (MR) Input

* Open-Drain RESET Output

* Immune to Short Negative SENSE voltage

* Guaranteed Reset Valid to VCC: 0.8V