TLF11070

October 1990

MM58167B

Microprocessor Real Time Clock

General Description

The MM58167B is a low threshold metal gate CMOS circuit

that functions as a real time clock in bus oriented microproc-

essor systems The device includes an addressable real

time counter 56 bits of RAM and two interrupt outputs A

POWER DOWN input allows the chip to be disabled from

the rest of the system for standby low power operation The

time base is a 32768 kHz crystal oscillator

Features

Y

Microprocessor compatible (8-bit data bus)

Y

Milliseconds through month counters

Y

56 bits of RAM with comparator to compare the real

time counter to the RAM data

Y

2 INTERRUPT OUTPUTS with 8 possible interrupt

signals

Y

POWER DOWN input that disables all inputs and out-

puts except for one of the interrupts

Y

Status bit to indicate rollover during a read

Y

32768 kHz crystal oscillator

Y

Four-year calendar (no leap year)

Y

24-hour clock

Connection Diagrams

Dual-In-Line Package

TLF11070 – 1

Top View

Order Number MM58167BN

See NS Package Number N24A

PCC Package

TLF11070 – 2

Top View

Order Number MM58167BV

See NS Package Number V28A

TRI-STATE

is a registered trademark of National Semiconductor Corporation

C1995 National Semiconductor Corporation

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