BQ3287AMT-SB2 Datasheet, PDF (1/9 Pages) Texas Instruments – Real-Time Clock (RTC) Module

Not Recommended For New Designs
bq3287/bq3287A
Features
® Direct clock/calendar replace-
ment for IBM^® AT-compatible
computers and other applications
® Functionally compatible with the
DS1287/DS1287A and MC146818A
® 114 bytes of general nonvolatile
storage
® Integral lithium cell and crystal
® 160 ns cycle time allows fast bus
operation
® Selectable Intel or Motorola bus
timing
® 14 bytes for clock/calendar and
control
® BCD or binary format for clock
and calendar data
® Time of day in seconds, minutes,
and hours
- 12- or 24-hour format
- Optional daylight saving
adjustment
Real-Time Clock ^(RTC) Module
® Calendar in day of the week, day
of the month, months, and years
with automatic leap-year adjust-
ment
® Programmable square wave out-
put
® Three individually maskable in-
terrupt event flags:
- Periodic rates from 122 µs to
500 ms
bq3287A version is identical to the
bq3287, with the addition of the RAM
clear input.
The bq3287 is a fully compatible
real-time clock for IBM AT-
compatible computers and other ap-
plications. The bq3287 write-
protects the clock, calendar, and
storage registers during power fail-
ure. The integral backup energy
source then maintains data and op-
erates the clock and calendar.
- Time-of-day alarm once per
second to once per day
- End-of-clock update cycle
® Better than one minute per
month clock accuracy
General Description
The CMOS bq3287/bq3287A is a
low-power microprocessor periph-
eral providing a time-of-day clock
and 100-year calendar with alarm
features and battery operation.
Other features include three
maskable interrupt sources, square-
wave output, and 114 bytes of gen-
eral nonvolatile storage. The
As shipped from Benchmarq, the
real time clock is turned off to maxi-
mize battery capacity for in-system
operation.
The bq3287 is functionally equiva-
lent to the bq3285, except that the
battery (16, 20) and crystal (2, 3)
pins are not accessible. These pins
are connected internally to a coin
cell and quartz crystal. The coin cell
is sized to provide 10 years of data
retention and clock operation in the
absence of power. For a complete de-
scription of features, operating con-
ditions, electrical characteristics,
bus timing, and pin descriptions, see
the bq3285 data sheet.
Pin Connections
MOT 1
NC 2
NC 3
AD0 4
AD1 5
AD2 6
AD3 7
AD4 8
AD5 9
AD6 10
AD7 11
VSS 12
24 VCC
23 SQW
22 NC
21 NC/RCL
20 NC
19 INT
18 RST
17 DS
16 NC
15 R/W
14 AS
13 CS
Pin Names
AD0–AD7 Multiplexed address/data
input/output
MOT
Bus type select input
CS
Chip select input
AS
Address strobe input
DS
Data strobe input
R/W
Read/write input
INT
Interrupt request output
RST
SQW
NC
RCL
VCC
VSS
Reset input
Square wave output
No connect
RAM clear input
(bq3287A only)
+5V supply
Ground
24-Pin DIP Module
PN328701.eps
Sept. 1996 D
1