Rainbow Electronics DS17887 - 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
§ 8kB additional NV RAM
§ RAM clear input
§ Century register
§ Date alarm register
§ Compatible with existing BIOS for original
DS1287 functions
§ Available as chip (DS17885) or standalone
module with embedded battery and crystal
(DS17887)
§ 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
DS17887 24-Pin
Encapsulated Package
NC
AD1
AD3
AD4
AD5
AD6
AD7
GND
VCC
SQW
VBAUX
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
DS17885 24-Pin DIP
DS17885S 24-Pin SO
X2
AD1
AD3
AD4
AD5
AD6
AD7
GND
VCC
SQW
VBAUX
RCLR
VBAT
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
VBAT 2 27 RD
RCLR 3 26 GND
VBAUX 4 25 WR
SQW 5 24 ALE
VCC 6 23 CS
VCC 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
DS17885E 28-Pin TSOP
DS17885/DS17887
3V/5V Real-Time Clock
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