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                         19-6849; Rev 11/13 
 
 
FEATURES 
?  Measures Temperatures from -55癈 to 
+125癈; Fahrenheit Equivalent is -67癋 to 
257癋 
?  Real-Time Clock Counts Seconds, Minutes, 
Hours, Date of the Month, Month, Day of the 
Week, and Year with Leap Year 
Compensation Through the Year 2100 
?  Thermometer Accuracy is ?.0癈 (typ) 
?  Thermometer Resolution is 9 Bits 
(Expandable) 
?  Thermostatic and Time Alarm Settings Are 
User Definable; Dedicated Open-Drain Alarm 
Output 
?  32 Bytes SRAM for General Data Storage 
?  Data is Read From/Written to via a 2-Wire 
Serial Interface (Open Drain I/O Lines) 
?  Wide Power Supply Range (2.2V to 5.5V) 
?  Applications Include PCs/PDAs, Cellular 
Telephones, Office Equipment, Data Loggers, 
or Any Thermally Sensitive System 
?  8-Pin (150-mil) SO Package 
 
PIN CONFIGURATION 
 
 
 
 
 
 
 
 
 
 
 
 
PIN DESCRIPTION  
SDA    
- 2-Wire Serial Data Input/Output 
SCL     
- 2-Wire Serial Clock 
GND    
- Ground 
ALRM  
- Thermostat and Clock Alarm 
 
 
 Output 
X1 
 
- 32.768kHz Crystal Input 
X2 
 
- 32.768kHz Crystal Feedback  
 Output 
OSC    
- Buffered Oscillator Output 
V
DD
     
- Power-Supply Voltage (+2.2V to 
 
 
 +5V) 
 
DESCRIPTION 
The DS1629 2-wire digital thermometer and real-time clock (RTC) integrates the critical functions of a 
real-time clock and a temperature monitor in a small outline 8-pin SO package. Communication to the 
DS1629  is  accomplished  via  a  2-wire  interface.  The  wide  power-supply  range  and  minimal  power 
requirement  of  the  DS1629  allow  for  accurate  time/temperature  measurements  in  battery-powered 
applications. 
 
The digital thermometer provides 9-bit temperature readings which indicate the temperature of the device. 
No additional components are required; the device is truly a temperature-to-digital converter.  
 
The clock/calendar provides seconds, minutes, hours, day, date of the month, day of the week, month, and 
year. The end of the month date is automatically adjusted for months with less than 31 days, including 
corrections for leap years. It operates in either a 12- or 24-hour format with AM/PM indicator in 12-hour 
mode. The  crystal oscillator frequency is internally divided, as specified by device configuration. An 
open-drain output is provided that can be used as the oscillator input for a microcontroller. 
DS1629 
2-Wire Digital Thermometer 
and Real-Time Clock 
1 
2 
3 
4 
8 
7 
6 
5 
GND 
ALRM 
SCL 
SDA 
V
DD
 
OSC 
X1 
X2 
SO 
1    mil