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