DS1688_05 [DALLAS]
3V/5V Serialized Real-Time Clocks with NV RAM Control; 3V / 5V串行实时时钟，带有非易失RAM控制器
| 型号： | DS1688_05 |
| 厂家： | 
DALLAS SEMICONDUCTOR |
| 描述： | 3V/5V Serialized Real-Time Clocks with NV RAM Control |
| 文件： | 总6页 (文件大小：395K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DS1688/DS1691
3V/5V Serialized Real-Time Clocks
with NV RAM Control
www.maxim-ic.com
GENERAL DESCRIPTION
FEATURES
The DS1688/DS1691 are real-time clocks
(RTCs) designed as successors to the industry
Incorporates Industry Standard DS1287 PC
Clock Plus Enhanced Features:
standard DS1285, DS1385, DS1485, and ꢀ +3V or +5V Operation
DS1585 PC real-time clocks. These devices ꢀ 64-Bit Silicon Serial Number
provide the industry standard DS1285 clock ꢀ 64-Bit Customer Specific ROM or
function with the new feature of either +3.0V or
Additional Serial Number Available
+5.0V operation and automatic backup and write ꢀ Power Control Circuitry Supports System
protection to an external SRAM. The DS1688
also incorporates a number of enhanced features
Power-On from Date/Time Alarm or Key
Closure
including a silicon serial number, power-on/off ꢀ Automatic Battery Backup and Write
control circuitry, 114 bytes of user NV SRAM,
Protection to External SRAM
power-on elapsed timer, and power-cycle ꢀ Crystal Select Bit Allows RTC to Operate
counter.
with 6Pf or 12.5Pf Crystal
ꢀ 114 Bytes User NV RAM
ꢀ Auxiliary Battery Input
ꢀ RAM Clear Input
PIN CONFIGURATIONS
TOP VIEW
ꢀ Century Register
ꢀ 32kHz 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 IC (DS1688) or Stand-Alone
Module with Embedded Battery and
Crystal (DS1691)
ꢀ Timekeeping Algorithm Includes Leap
Year Compensation Valid Up to 2100
ORDERING INFORMATION
PART
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
VOLTAGE (V)
3 to 5
PIN-PACKAGE
28 SO (0.330″)
28 SO (0.330″)
28 EDIP (0.740″)
TOP MARK*
DS1688S
DS1688S
DS1688S
DS1688S+
3 to 5
3 to 5
DS1691
DS1691
+ Denotes a lead-free/RoHS-compliant device.
+ A “+” anywhere on the top mark denotes a lead-free/RoHS-compliant device.
1 of 6
REV: 112205
DS1688/DS1691
DETAILED DESCRIPTION
Each DS1688/DS1691 is individually manufactured with a unique 64-bit serial number as well as an
additional 64-bit customer-specific ROM or serial number. The serial number is programmed and tested
at Dallas to ensure that no two devices are alike. The serial number can be used to electronically identify
a system for purposes such as establishment of a network node address or for maintenance tracking.
Customers can reserve blocks of available numbers from Dallas Semiconductor.
The serialized RTCs also incorporate power-control circuitry, 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 triggered by one or either of these events, and can be used to turn on an external power supply.
The PWR pin is under software control, so that when a task is complete, the system power can then be
shut down.
The DS1688/DS1691 incorporate 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 warranty requirements.
Automatic backup and write protection for an external SRAM is provided through the VCCO and CEO
pins. The lithium energy source used to permanently power the RTC is also used to retain RAM data in
the absence of VCC power through the VCCO pin. The chip enable output to RAM (CEO) is controlled
during power transients to prevent data corruption.
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 32.768kHz crystal, and a lithium battery in a complete, self-
contained 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 VCC is guaranteed.
For a complete description of operating conditions, electrical characteristics, bus timing, and pin
descriptions other than the SQW output, refer to the DS1689/DS1693 data sheet, available online at
www.maxim-ic.com/DS1689.
2 of 6
DS1688/DS1691
PIN DESCRIPTION
PIN
NAME
FUNCTION
SO
1
EDIP
1
VBAUX
X1, X2
RCLR
AD0–AD7
PWR
GND
KS
Auxiliary Battery Supply
2, 3
4
—
4
Crystal Input, Crystal Output
Active-Low RAM Clear Input
Muxed Address/Data Bus
Active-Low Power-On Interrupt Output
Ground
Active-Low Kickstart Input
Active-Low Chip Select Input
Address Strobe
Active-Low Write Data Strobe
Active-Low Read Data Strobe
+3V or +5V Power Select
Active-Low Interrupt Request Output
Battery + Supply
5–12
13
5–12
13
14
15
16
17
18
20
21
22
—
14, 19
15
16
CS
ALE
WR
RD
PSEL
IRQ
17
18
20
21
22
23
VBAT
Square-Wave Output. This signal functions identical to the
DS1689/DS1693 with an exception occurring at power-up. A
32kHz square wave is output on this pin, tREC, after a power-up
condition has been detected. This condition sets the following
bits, enabling the 32kHz output: DV1 = 1, SQWE = 1, and E32K
= 1. The square wave is output on this pin if either SQWE = 1 or
E32K = 1.
24
24
SQW
25
26
27
28
25
26
VCCO
VCCI
CEO
CEI
RAM Power-Supply Output
+3V or +5V Main Supply
27
Active-Low RAM Chip Enable Out
28
Active-Low RAM Chip Enable In
2, 3, 19,
23
—
N.C.
No Connection
3 of 6
DS1688/DS1691
PACKAGE INFORMATION
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline
information, go to www.maxim-ic.com/DallasPackInfo.)
4 of 6
DS1688/DS1691
PACKAGE INFORMATION (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline
information, go to www.maxim-ic.com/DallasPackInfo.)
5 of 6
DS1688/DS1691
PACKAGE INFORMATION (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline
information, go to www.maxim-ic.com/DallasPackInfo.)
6 of 6
Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product.
No circuit patent licenses are implied. Maxim/Dallas Semiconductor reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products • Printed USA
The Maxim logo is a registered trademark of Maxim Integrated Products, Inc. The Dallas logo is a registered trademark of Dallas Semiconductor Corporation.
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