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092800
FEATURES
Incorporates industry standard DS1287 PC clock
plus enhanced features:
+3- or +5V operation
64-bit silicon serial number
64-bit customer specific ROM or additional
serial number available
Power control circuitry supports system
power-on from date/time alarm or key closure
Automatic battery backup and write
protection to external SRAM
Crystal select bit allows RTC to operate with
6 pF or 12.5 pF crystal
114 bytes user NV RAM
Auxiliary battery input
RAM clear input
Century register
32 kHz output for power management
32-bit V
CC
powered elapsed time counter
32-bit V
BAT
powered elapsed time counter
16-bit power cycle counter
Compatible with existing BIOS for original
DS1287 functions
Available as IC (DS1689) or standalone
module with embedded battery and crystal
(DS1693)
IC is available in industrial temperature
version
Timekeeping algorithm includes leap year
compensation valid up to 2100
ORDERING INFORMATION
PART #
DS1689S
DS1689SN
DS1693
DESCRIPTION
RTC IC, 28-pin SOIC
RTC IC, 28-pin SOIC IND
RTC Module; 28-pin DIP
PIN ASSIGNMENT
PIN DESCRIPTION
X1
X2
RCLR
AD0-AD7
PWR
- Crystal Input
- Crystal Output
- RAM Clear Input
- Mux’ed Address/Data Bus
- Power-on Interrupt Output
(Open drain)
- Kickstart Input
- RTC Chip Select Input
- RTC Address Strobe
- RTC Write Data Strobe
- RTC Read Data Strobe
- RAM Power Supply Output
- Interrupt Request Output
(Open drain)
- Square Wave Output
- +3- or +5V Main Supply
- Ground
- Battery + Supply
- Auxiliary Battery Supply
- +3- or +5V Power Select
- RAM Chip Enable In
- RAM Chip Enable Out
KS
CS
ALE
WR
RD
V
CCO
IRQ
SQW
V
CCI
GND
V
BAT
V
BAUX
PSEL
CEI
CEO
DS1689/DS1693
3-Volt/5-Volt Serialized Real-Time Clock
with NV RAM Control
www.maxim-ic.com
V
BAUX
DS1689S 28-Pin SOIC
(330-mil)
13
14
27
26
25
24
23
22
21
20
19
18
17
16
1
2
3
4
5
6
7
8
9
10
11
12
28
15
CEI
CEO
V
CCI
V
CCO
SQW
V
BAT
IRQ
PSEL
RD
GND
WR
ALE
CS
KS
X2
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
X1
RCLR
DS1693 28-Pin Encapsulated Package
(740-mil)
13
14
27
26
25
24
23
22
21
20
19
18
17
16
NC
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
CEI
CEO
V
CCI
V
CCO
SQW
NC
IRQ
PSEL
RD
NC
WR
ALE
CS
KS
1
2
3
4
5
6
7
8
9
10
11
12
28
15
NC
RCLR
V
BAUX