Rainbow Electronics DS17487 - Manual

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FEATURES
Incorporates industry standard DS1287 PC clock
plus enhanced features:
§ Y2K compliant
§ +3V or +5V operation
§ SMI recovery stack
§ 64-bit silicon serial number
§ Power-control circuitry supports system
power-on from date/time alarm or key
closure
§ 32kHz output on power-up
§ Crystal select bit allows RTC to operate with
6pF or 12.5pF crystal
§ 114 bytes user NV RAM
§ Auxiliary battery input
§ 4kB additional NV RAM
§ RAM clear input
§ Century register
§ Date alarm register
§ Compatible with existing BIOS for original
DS1287 functions
§ Available as chip (DS17485) or standalone
module with embedded battery and crystal
(DS17487)
§ Timekeeping algorithm includes leap-year
compensation valid up to 2100
§ Underwriters Laboratory (UL) recognized
TYPICAL OPERATING CIRCUIT
PIN ASSIGNMENT
PWR 1
2
3
4
5
6
7
8
9
10
11
12
23
DS17487 24-Pin
Encapsulated Package
NC
AD1
AD3
AD4
AD5
AD6
AD7
GND
V
CC
SQW
V
BAUX
RCLR
NC
IRQ
KS
RD
NC
WR
ALE
CS
24
22
21
20
19
18
17
16
15
14
13
NC
AD0
AD2
PWR 1
2
3
4
5
6
7
8
9
10
11
12
23
DS17485 24-Pin DIP
DS17485S 24-Pin SO
X2
AD1
AD3
AD4
AD5
AD6
AD7
GND
V
CC
SQW
V
BAUX
RCLR
V
BAT
IRQ
KS
RD
GND
WR
ALE
CS
24
22
21
20
19
18
17
16
15
14
13
X1
AD0
AD2
IRQ 1 28 KS
V
BAT
2 27 RD
RCLR 3 26 GND
V
BAUX
4 25 WR
SQW 5 24 ALE
V
CC
6 23 CS
V
CC
7 22 GND
PWR 8 21 GND
X1 9 20 AD7
X2 10 19 AD6
NC 11 18 NC
ADO 12 17 AD5
AD1 13 16 AD4
AD2 14 15 AD3
DS17485E 28-Pin TSOP
DS17485/DS17487
3V/5V Real-Time Clock
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