Philips Semiconductors

Product data

NE56631-XX

Active-LOW system reset

2003 Feb 14

8

APPLICATION INFORMATION

RESET

SUPPLY

GND

NE56631-XX

CPU

SL01741

Figure 11. Conventional reset application for NE56631-XX.

RESET

SUPPLY

GND

CPU

SL01742

R

D

Figure 12. Power On Reset circuit for NE56631-XX.

The Power ON Reset Circuit shown in Figure 12 is an example of

obtaining a stable reset condition upon power-up. If power supply

below the minimum operating voltage (0.85 V). To overcome this

undesirable response, a resistor in placed between positive supply,

circuit solution works reasonably well for power-up as long as the

power supply voltage rises faster than the RC time constant. The

RC network provides the necessary reset delay to hold the

microprocessor in reset until its circuitry settles down and normal

operation begins. When the supply turns off, the diode provides a

path for the capacitor to discharge to more quickly assert logic LOW

reset.