1998 Apr 16

9

Philips Semiconductors

Product specification

Threshold detector and reset generator

PCF1252-X family

Fig.10 Data retention circuit for memory back-up systems.

handbook, full pagewidth

MICROCONTROLLER/

MICROPROCESSOR

VDD

VDD

RESET

INT

MGC924

RESET

COMIN

VOLTAGE

REGULATOR

COMOUT

PCF1252-X

SELECT

VSS

VDD

VSS

VSS

CT

RAM

VRAM

addres/data bus

12 V

5 V

1 M

Ω

6 M

Ω

1 nF

10

µF

CHIP-

DECODING

LOGIC

R/W

CS

Fig.11 Data retention circuit with external switchable reset for systems with a single voltage supply.

(1) For external reset application, the SELECT input must be debounced.

handbook, full pagewidth

MICROCONTROLLER/

MICROPROCESSOR

VDD

VDD

VDD

RESET

RAM

INT

MGC925

RESET

COMIN

PCF1252-X

SELECT

external reset

input signal (1)

VSS

VDD

VSS

VSS

VSS

CT

10

µF

POWF