Datasheet > BQ4287

BQ4287

更新时间： 2024-09-09 22:25:55

品牌	Logo	应用领域
德州仪器 - TI		时钟
页数	文件大小	规格书
8页	144K
描述
Real-Time Clock Module With NVRAM Control

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中文翻译

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数据手册
替代型号

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BQ4287 数据手册

bq4287

Real-Time Clock Module With NVRAM Control

Features

➤ Time of day in seconds, minutes,

114 byt es of gen er a l n on vola t ile

storage.

and hours

➤ Direct clock/calendar replace-

ment for IBM®

- ^{12- or 24-hour format}

The bq4287 write-protects the clock,

calendar, and storage registers dur-

in g p ower fa ilu r e. Th e in t egr a l

backup energy source then main-

tains data and operates the clock

and calendar.

- ^{Optional daylight saving}

AT-compatible computers and

other applications

adjustment

➤ Programmable square wave out-

➤ Functionally compatible with the

DS1287/DS1287A and

MC146818A

put

➤ Three individually maskable in-

The bq4287 uses its integral battery-

backup controller and battery to make

a standard CMOS SRAM nonvolatile

during power-fail conditions. During

power-fail, the bq4287 automatically

write-protects the external SRAM and

provides a V_CCoutput sourced from its

internal battery.

terrupt event flags:

➤ 114 bytes of general nonvolatile

storage

- ^{Periodic rates from 122}^µ^{s to}

500 ms

➤ Automatic backup supply and

write-protection to make external

SRAM nonvolatile

- ^{Time-of-day alarm once per}

second to once per day

- ^{End-of-clock update cycle}

➤ Integral lithium cell and crystal

The bq4287 is a fully compatible

real-time clock for IBM AT-compatible

computers and other applications.

➤ Better than one minute per

➤ 160 ns cycle time allows fast bus

month clock accuracy

operation

➤ Intel bus timing

General Description

As shipped from Benchma rq, the

backup cell is electrically isolated

from the memory. Following the first

application of V_CC, this isolation is

broken, and the backup cell provides

data retention to the clock, internal

RAM, V_OUT, and CE_OUTon subse-

quent power-downs.

➤ 14 bytes for clock/calendar and

control

The CMOS bq4287 is a low-power

microprocessor peripheral providing

a time-of-day clock and 100-year cal-

endar with alarm features and bat-

tery operation. Other features in-

clu de t h r ee m a sk a ble in t er r u pt

sources, square wave output, and

➤ BCD or binary format for clock

and calendar data

➤ Calendar in day of the week, day of

the month, months, and years with

automatic leap-year adjustment

The bq4287 is functionally equiva-

lent to the bq4285, except that the

battery (16, 20) and crystal pins (2,

3) are not accessible. These pins are

connected internally to a coin cell

and quartz crystal. The coin cell pro-

vides 130m Ah of ca pa cit y. For a

complete description of features, op-

erating conditions, electrical charac-

teristics, bus timing, and pin de-

scr ipt ion s, see t h e bq4285 da t a

sheet.

Pin Connections

Pin Names

AD₀–AD₇

Multiplexed address/data

input/output

Chip select input

Address strobe input

Data strobe input

Read/write input

Interrupt request output

Reset input

OUT

SQW

ALE

OUT

INT

RST

SQW

CE_IN

CE_OUT

INT

RST

Caution:

Square wave output

RAM chip enable input

RAM chip enable output

No connect

Take care to avoid inadvertent dis-

charge through V_OUTand CE_OUT

after battery isolation has been

broken.

ALE

24-Pin DIP Module

V_OUT

V_CC

V_SS

Supply output

PN428701.eps

+5V supply

Ground

Nov. 1993 C

12 3 4 5 6 7 8

中文翻译

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BQ4287 替代型号

型号	品牌	替代类型	描述	数据表
BQ4285	TI	功能相似	Real-Time Clock RTC With NVRAM Control

与BQ4287相关器件

型号	品牌	获取价格	描述	数据表
BQ4287EMT	ETC	获取价格	Real-Time Clock
BQ4287EMT-N	ETC	获取价格	Real-Time Clock
BQ4287MT-	TI	获取价格	Real-Time Clock Module With NVRAM Control
BQ4287MT-SB2	TI	获取价格	Real-Time Clock Module With NVRAM Control
BQ4311LSH-N100	TI	获取价格	32KX8 NON-VOLATILE SRAM MODULE, 100ns, DMA28, SNAPHAT MODULE-28
BQ4311YSH-N70	TI	获取价格	32KX8 NON-VOLATILE SRAM MODULE, 70ns, DMA28, SNAPHAT MODULE-28
BQ-4704701%	VISHAY	获取价格	General Purpose Inductor, 470uH, 1%, 1 Element, Ferrite-Core
BQ-47047010%	VISHAY	获取价格	General Purpose Inductor, 470uH, 10%, 1 Element, Ferrite-Core
BQ-4704703%	VISHAY	获取价格	General Purpose Inductor, 470uH, 3%, 1 Element, Ferrite-Core
BQ-4704705%	VISHAY	获取价格	General Purpose Inductor, 470uH, 5%, 1 Element, Ferrite-Core

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