MC68HC68 데이터 시트보기 (PDF) - Motorola => Freescale

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MC68HC68

Real-Time Clock plus RAM with Serial Interface

Motorola => Freescale 

MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

Real-Time Clock plus RAM with

Serial Interface

CMOS

The MC68HC68T1 HCMOS Clock/RAM peripheral contains a real–time

clock/calendar, a 32 x 8 static RAM, and a synchronous, serial, three–wire

interface for communication with a microcontroller or processor. Operating in a

burst mode, successive Clock/RAM locations can be read or written using only

a single starting address. An on–chip oscillator allows acceptance of a

selectable crystal frequency or the device can be programmed to accept a

50/60 Hz line input frequency.

The LINE and system voltage (VSYS) pins give the MC68HC68T1 the

capability for sensing power–up/power–down conditions, a capability useful for

battery–backup systems. The device has an interrupt output capable of

signaling a microcontroller or processor of an alarm, periodic interrupt, or power

sense condition. An alarm can be set for comparison with the seconds, minutes,

and hours registers. This alarm can be used in conjunction with the power

supply enable (PSE) output to initiate a system power–up sequence if the VSYS

pin is powered to the proper level.

A software power–down sequence can be initiated by setting a bit in the

interrupt control register. This applies a reset to the CPU via the CPUR pin, sets

the clock out (CLKOUT) and PSE pins low, and disables the serial interface.

This condition is held until a rising edge is sensed on the VSYS input pin,

signaling system power coming on, or by activation of a previously enabled

interrupt if the VSYS pin is powered up.

A watchdog circuit can be enabled that requires the microcontroller or

processor to toggle the slave select (SS) pin of the MC68HC68T1 periodically

without performing a serial transfer. If this condition is not met, the CPUR line

resets the CPU.

• Full Clock Features — Seconds, Minutes, Hours (AM/PM), Day–of–Week,

Date, Month, Year (0 – 99), Auto Leap Year

t • 32–Byte General Purpose RAM

• Direct Interface to Motorola SPI and National MICROWIRE Serial Data

Ports

• Minimum Timekeeping Voltage: 2.2 V

• Burst Mode for Reading/Writing Successive Addresses in Clock/RAM

• Selectable Crystal or 50/60 Hz Line Input Frequency

• Clock Registers Utilize BCD Data

• Buffered Clock Output for Driving CPU Clock, Timer, Colon, or LCD

Backplane

• Power–On Reset with First Time–Up Bit

• Freeze Circuit Eliminates Software Overhead During a Clock Read

• Three Independent Interrupt Modes — Alarm, Periodic, or Power–Down

• CPU Reset Output — Provides Orderly Power–Up/Power–Down

• Watchdog Circuit

• Pin–for–Pin Replacement for CDP68HC68T1

• Chip Complexity: 8500 FETs or 2125 Equivalent Gates

• Also See Application Notes ANE425 “Use of the MC68HC68T1 RTC with

M6805 Microprocessor”, AN457 “Providing a Real–Time Clock for the

MC68302”, and AN1065 “Use of the MC68HC68T1 Real–Time Clock with

Multiple Time Bases”

MICROWIRE is a trademark of National Semiconductor Inc.

REV 2

2/96

©MOMoTtoOroRla,OInLc.A1996

Order this document

by MC68HC68T1/D

MC68HC68T1

16

1

P SUFFIX

PLASTIC DIP

CASE 648

16

1

DW SUFFIX

SOG PACKAGE

CASE 751G

ORDERING INFORMATION

MC68HC68T1P Plastic DIP

MC68HC68T1DW SOG Package

PIN ASSIGNMENT

CLKOUT 1

CPUR 2

INT 3

SCK 4

MOSI 5

MISO 6

SS 7

VSS 8

16 VDD

15 XTALout

14 XTALin

13 VBATT

12 VSYS

11 LINE

10 POR

9 PSE

MC68HC68T1

1

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