DS1688S [DALLAS]
3 Volt/5 Volt Serialized Real Time Clock with NV RAM Control; 3伏/ 10伏序列化实时时钟，带有非易失RAM控制器
| 型号： | DS1688S |
| 厂家： | 
DALLAS SEMICONDUCTOR |
| 描述： | 3 Volt/5 Volt Serialized Real Time Clock with NV RAM Control |
| 文件： | 总5页 (文件大小：50K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DS1688/DS1691
DS1688/DS1691
3 Volt/5 Volt Serialized Real Time Clock
with NV RAM Control
FEATURES
PIN ASSIGNMENT
Incorporates industry standard DS1287 PC clock plus
enhanced features:
V
1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CEI
V
1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CEI
BAUX
X1
BAUX
X1
2
CEO
2
CEO
X2
3
V
X2
3
V
CCI
• +3 or +5 volt operation
CCI
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
4
V
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
4
V
CCO
CCO
5
SQW
5
SQW
• 64–bit Silicon serial number
6
V
6
V
BAT
BAT
• 64–bit customer specific ROM or additional serial
number available
7
IRQ
PSEL
RD
7
IRQ
PSEL
RD
8
8
9
9
• Power control circuitry supports system power on
from date/time alarm or key closure
10
11
12
13
14
GND
WR
ALE
CS
10
11
12
13
14
GND
WR
ALE
CS
• Automatic battery backup and write protection to
external SRAM
KS
KS
DS1688 28–PIN DIP
(600 MIL)
DS1688S 28–PIN SOIC
(330 MIL)
• Crystal select bit allows RTC to operate with 6 pF or
12.5 pF crystal
V
1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CEI
BAUX
NC
• 114 bytes user NVRAM
• Auxiliary battery input
• RAM clear input
2
CEO
NC
3
V
V
CCI
RCLR
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
PWR
GND
4
CCO
5
SQW
NC
6
• Century register
7
IRQ
PSEL
RD
8
• 32 KHz output for power management
9
10
11
12
13
14
NC
• 32–bit V powered elapsed time counter
CC
WR
ALE
CS
• 32–bit V
powered elapsed time counter
BAT
• 16–bit power cycle counter
KS
• Compatible with existing BIOS for original DS1287
functions
DS1691 28–PIN ENCAPSU-
LATED PACKAGE (740 MIL)
• Available as chip (DS1688) or stand–alone module
PIN DESCRIPTION
with embedded battery and crystal (DS1691)
X1
–
–
–
–
–
–
–
–
–
–
–
Crystal Input
• Timekeepingalgorithmincludesleapyearcompensa-
tion valid up to 2100
X2
Crystal Output
RCLR
AD0-AD7
PWR
KS
RAM Clear Input
Mux’ed Address/Data Bus
Power–on Interrupt Output
Kickstart Input
ORDERING INFORMATION
PART #
DS1688
DS1688S
DS1691
DESCRIPTION
CS
ALE
WR
RTC Chip Select Input
RTC Address Strobe
RTC Write Data Strobe
RTC Read Data Strobe
RAM Power Supply Output
RTC Chip, 28–pin DIP
RTC Chip, 28–pin SOIC
RTC Module; 28–pin DIP
RD
V
CCO
030598 1/5
DS1688/DS1691
IRQ
SQW
–
–
–
–
–
–
–
–
–
Interrupt Request Output
Square Wave Output
+3 or +5 Volt Main Supply
Ground
The DS1688/DS1691 incorporates a power on elapsed
time counter, a power on cycle counter, and a battery
powered continuous counter. These three counters
provide valuable information for maintenance and war-
ranty requirements.
V
CCI
GND
V
V
Battery + Supply
BAT
Auxiliary Battery Supply
+3 or +5 Volt Power Select
RAM Chip Enable In
RAM Chip Enable Out
BAUX
Automatic backup and write protection for an external
PSEL
CEI
CEO
SRAM is provided through the V
and CEO pins. The
CCO
lithium energy source used to permanently power the real
time clock is also used to retain RAM data in the absence
of V power through the V
put to RAM (CEO) is controlled during power transients to
prevent data corruption.
pin. The chip enable out-
CC
CCO
DESCRIPTION
The DS1688/DS1691 is a real time clock (RTC) de-
signedasasuccessortotheindustrystandardDS1285,
DS1385, DS1485, and DS1585 PC real time clocks.
This device provides the industry standard DS1285
clockfunctionwiththenewfeatureofeither+3.0 or+5.0
volt operation and automatic backup and write protec-
tion to an external SRAM. The DS1688 also incorpo-
rates a number of enhanced features including a silicon
serialnumber,poweron/offcontrolcircuitry, 114bytesof
user NVSRAM, power on elapsed timer, and power
cycle counter.
The DS1688 is a clock/calendar chip with the features
described above. An external crystal and battery are
the only components required to maintain time–of–day
and memory status in the absence of power. The
DS1691 incorporates the DS1688 chip, a 32.768 KHz
crystal, and a lithium battery in a complete, self–con-
tained timekeeping module. The entire unit is fully
tested at Dallas Semiconductor such that a minimum of
10 years of timekeeping and data retention in the
absence of V is guaranteed.
CC
Each DS1688/DS1691 is individually manufactured
with a unique 64–bit serial number as well as an addi-
tional 64–bit customer specific ROM or serial number.
The serial number is programmed and tested at Dallas
to insure that no two devices are alike. The serial num-
ber can be used to electronically identify a system for
purposes such as establishment of a network node ad-
dress or for maintenance tracking. Blocks of available
numbers from Dallas Semiconductor can be reserved
by the customer.
For a complete description of operating conditions,
electrical characteristics, bus timing, and pin descrip-
tions other than the SQW output, see the
DS1689/DS1693 data sheet.
SIGNAL DESCRIPTION
SQW (Square Wave Output) – The SQW output signal
functions identical to the DS1689/DS1693 with an
exception occurring at power–up. A 32 KHz square
wave will be output on this pin, t
, after a power–up
The serialized RTC’s also incorporate power control cir-
cuitry which allows the system to be powered on via an
external stimulus, such as a keyboard or by a time and
date (wake up) alarm. The PWR output pin can be trig-
gered by one or either of these events, and can be used
to turn on an external power supply. The PWR pin is un-
der software control, so that when a task is complete,
the system power can then be shut down.
REC
conditionhasbeendetected. Thisconditionsetsthefol-
lowing bits enabling the 32 KHz output; DV1=1,
SQWE=1, andE32K=1. Thesquarewavewillbeoutput
on this pin if either SQWE=1 or E32K=1.
030598 2/5
DS1688/DS1691
DS1688 28–PIN DIP
PKG
28–PIN
DIM
MIN
MAX
A IN.
MM
1.445
36.70
1.470
37.34
B
D
B IN.
MM
0.530
13.46
0.550
13.97
C IN.
MM
0.140
3.56
0.160
4.06
1
D IN.
MM
0.600
15.24
0.625
15.88
A
E IN.
MM
0.015
0.38
0.040
1.02
F IN.
MM
0.120
3.05
0.145
3.68
C
F
G IN.
MM
0.090
2.29
0.110
2.79
H IN.
MM
0.625
15.88
0.675
17.15
E
K
G
J IN.
MM
0.008
0.20
0.012
0.30
K IN.
MM
0.015
0.38
0.022
0.56
J
H
030598 3/5
DS1688/DS1691
DS1688S 28–PIN SOIC
K
G
PKG
28–PIN
MIN
DIM
MAX
A IN.
MM
0.706
17.93
0.728
18.49
B IN.
MM
0.338
8.58
0.350
8.89
C IN.
MM
0.086
2.18
0.110
2.79
D IN.
MM
0.020
0.58
0.050
1.27
E IN.
MM
0.002
0.05
0.014
0.36
F IN.
MM
0.090
2.29
0.124
3.15
0.050
1.27
BSC
G IN.
MM
C
H IN.
MM
0.460
11.68
0.480
12.19
A
J IN.
MM
0.006
0.15
0.013
0.33
E
K IN.
MM
0.014
0.36
0.020
0.51
B
F
0–8 deg. typ.
J
H
D
030598 4/5
DS1688/DS1691
DS1691 28–PIN 740 MIL MODULE
15
28
PKG
28–PIN
MIN MAX
DIM
A
IN.
MM
1.520
38.61
1.540
39.12
B
C
D
E
F
IN.
MM
0.695
17.65
0.740
18.80
1
14
IN.
MM
0.350
8.89
0.375
9.52
A
IN.
MM
0.100
2.54
0.130
3.30
IN.
MM
0.015
0.38
0.030
0.76
IN.
MM
0.110
2.79
0.140
3.56
C
E
G
H
J
IN.
MM
0.090
2.29
0.110
2.79
IN.
MM
0.590
14.99
0.630
16.00
F
D
K
G
IN.
MM
0.008
0.20
0.012
0.30
13 EQUAL SPACES AT
.100 ± .010 TNA
K
IN.
MM
0.015
0.38
0.021
0.53
NOTE:
PINS 2, 3, 19 AND 23 ARE MISSING BY DESIGN.
J
H
B
030598 5/5
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