DESCRIPTION

The L9705 is a bipolar monolithic integrated circuit for monitoring the status of up to four contacts connected to GND and up to four contacts connected to the battery. The contact sense input supply the contact current and perform the contact resistance comparison function.

At the output the contact status is translated into a logical LOW level (contact closed) or logical HIGH level (contact open).

■ OPERATING DC SUPPLY VOLTAGE RANGE 5V TO 25V

■ SUPPLY OVERVOLTAGE PULSE UP TO 40V

■ VERY LOW STAND-BY QUIESCENT

CURRENT, MAX 50µA

■ INTERNAL CLAMPING DIODES AT

CONTACT INPUTS TO Vs AND gnd WITH

PULSE CURRENT CAPABILITY UP TO

+50mA, -75mA

■ CHIP ENABLE FUNCTION AND

TRISTATE OUTPUTS FOR PARALLEL BUS

CONNECTION

■ NOMINAL CONTACT CURRENTS OF 10mA

DEFINED WITH EXTERNAL CONTACT

SERIES RESISTORS RIN1-8

■ CONTACT STATUS MONITORING BY

MEANS OF COMPARING THE RESISTANCE

AT CONTACT SENSE INPUTS WITH THE

INTERNAL REFERENCE RESISTOR VALUE

■ RESISTANCE COMPARING WITH

HYSTERESIS FOR HIGH NOISE IMMUNITY

AND IMMUNITY TO GROUND AND BATTERY POTENTIAL DIFFERENCES