DS1688(1998) 데이터 시트보기 (PDF) - Dallas Semiconductor -> Maxim Integrated
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DS1688
(Rev.:1998)
(Rev.:1998)
Dallas Semiconductor -> Maxim Integrated
DS1688 Datasheet PDF : 5 Pages
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DS1688/DS1691
DS1688/DS1691
3 Volt/5 Volt Serialized Real Time Clock
with NV RAM Control
FEATURES
Incorporates industry standard DS1287 PC clock plus
enhanced features:
• +3 or +5 volt 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 NVRAM
• Auxiliary battery input
• RAM clear input
• Century register
• 32 KHz output for power management
• 32–bit VCC powered elapsed time counter
• 32–bit VBAT powered elapsed time counter
• 16–bit power cycle counter
• Compatible with existing BIOS for original DS1287
functions
• Available as chip (DS1688) or stand–alone module
with embedded battery and crystal (DS1691)
• Timekeeping algorithm includes leap year compensa-
tion valid up to 2100
ORDERING INFORMATION
PART #
DS1688
DS1688S
DS1691
DESCRIPTION
RTC Chip, 28–pin DIP
RTC Chip, 28–pin SOIC
RTC Module; 28–pin DIP
PIN ASSIGNMENT
VBAUX 1
X1 2
X2 3
RCLR 4
AD0 5
AD1 6
AD2 7
AD3 8
AD4 9
AD5 10
AD6 11
AD7 12
PWR 13
GND 14
28 CEI
27 CEO
26 VCCI
25 VCCO
24 SQW
23 VBAT
22 IRQ
21 PSEL
20 RD
19 GND
18 WR
17 ALE
16 CS
15 KS
DS1688 28–PIN DIP
(600 MIL)
VBAUX 1
NC 2
NC 3
RCLR 4
AD0 5
AD1 6
AD2 7
AD3 8
AD4 9
AD5 10
AD6 11
AD7 12
PWR 13
GND 14
VBAUX
X1
X2
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
28
CEI
2
27
CEO
3
26
VCCI
4
25
VCCO
5
24
SQW
6
23
VBAT
7
22
IRQ
8
21
PSEL
9
20
RD
10
19
GND
11
18
WR
12
17
ALE
13
16
CS
14
15
KS
DS1688S 28–PIN SOIC
(330 MIL)
CEI
CEO
VCCI
VCCO
SQW
NC
IRQ
PSEL
RD
NC
WR
ALE
CS
KS
DS1691 28–PIN ENCAPSU-
LATED PACKAGE (740 MIL)
PIN DESCRIPTION
X1
– Crystal Input
X2
– Crystal Output
RCLR
– RAM Clear Input
AD0-AD7
– Mux’ed Address/Data Bus
PWR
– Power–on Interrupt Output
KS
– Kickstart Input
CS
– RTC Chip Select Input
ALE
– RTC Address Strobe
WR
– RTC Write Data Strobe
RD
– RTC Read Data Strobe
VCCO
– RAM Power Supply Output
030598 1/5
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