DS17285 Datasheet, PDF (1/38 Pages) Dallas Semiconductor – 3V/5V Real-Time Clock

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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
§ 2kB additional NV RAM
§ RAM clear input
§ Century register
§ Date alarm register
§ Compatible with existing BIOS for original
DS1287 functions
§ Available as chip (DS17285) or standalone
module with embedded battery and crystal
(DS17287)
§ Timekeeping algorithm includes leap-year
compensation valid up to 2100
§ Underwriters Laboratory (UL) recognized
TYPICAL OPERATING CIRCUIT
DS17285/DS17287
3V/5V Real-Time Clock
PIN ASSIGNMENT
PWR 1
X1 ₂
X2 3
AD0 4
AD1 5
AD2 6
AD3 7
AD4 8
AD5 9
AD6 10
AD7 11
GND ¹²
24 VCC
23 SQW
22
VBAUX
21 RCLR
20 VBAT
19 IRQ
18 KS
17 RD
16 ^GND
15 WR
14
ALE
13 CS
DS17285 24-Pin DIP
DS17285S 24-Pin SO
PWR 1
NC ₂
NC 3
AD0 4
AD1 5
AD2 6
AD3 7
AD4 8
AD5 9
AD6 10
AD7 11
GND ¹²
24 VCC
23 SQW
22
VBAUX
21 RCLR
20 NC
19 IRQ
18 KS
17 RD
16 ^NC
15 WR
14
ALE
13 CS
DS17287 24-Pin
Encapsulated Package
IRQ
VBAT
RCLR
VBAUX
SQW
VCC
VCC
PWR
X1
X2
NC
ADO
AD1
AD2
1
28
KS
2
27
RD
3
26
GND
4
25
WR
5
24
ALE
6
23
CS
7
22
GND
8
21
GND
9
20
AD7
10
19
AD6
11
18
NC
12
17
AD5
13
16
AD4
14
15
AD3
DS17285E 28-Pin TSOP
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