DS1629 View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS1629

2-Wire Digital Thermometer and Real Time Clock

Dallas Semiconductor -> Maxim Integrated 

DS1629

The open-drain alarm output of the DS1629 will become active when either the measured temperature

exceeds the programmed over-temperature limit (TH) or current time reaches the programmed alarm

setting. The user can configure which event (time only, temperature only, either, or neither) will generate

an alarm condition. For storage of general system data or time/temperature datalogging, the DS1629

features 32 bytes of SRAM. Applications for the DS1629 include personal computers/ PDAs, cellular

telephones, office equipment, thermal dataloggers, or any microprocessor-based, thermally-sensitive

system.

DETAILED PIN DESCRIPTION Table 1

PIN SYMBOL DESCRIPTION

1

SDA Data input/output pin for 2-wire serial communication port.

2

SCL Clock input/output pin for 2-wire serial communication port.

3

ALRM Alarm output Open drain time/temperature alarm output with configurable active

state

4

GND Ground pin.

5

X2

32.768 kHz Feedback Output .

6

X1

32.768 kHz Crystal input.

7

OSC Oscillator Output. Open-drain output used for microcontroller clock input.

8

VDD Supply voltage 2.2V - 5.5V input power pin.

OVERVIEW

A block diagram of the DS1629 is shown in Figure 1.

The DS1629 consists of six major components:

1. Direct-to-digital temperature sensor

2. Real time clock

3. 2-wire interface

4. Data registers

5. Thermal & clock alarm comparators

6. Oscillator divider & buffer

The factory-calibrated temperature sensor requires no external components. The very first time the

DS1629 is powered up it begins temperature conversions, and performs conversions continuously. The

host can periodically read the value in the temperature register, which contains the last completed

conversion. As conversions are performed in the background, reading the temperature register does not

affect the conversion in progress.

The host can modify DS1629 configuration such that it does not power up in the auto-convert or

continuous convert modes. This could be beneficial in power-sensitive applications.

The real time clock/calendar maintains a BCD count of seconds, minutes, hours, day of the week, day of

the month, month, and year. It does so with an internal oscillator/ divider and a required 32.768 kHz

crystal. The end of the month date is automatically updated for months with less than 31 days, including

compensation for leap years through the year 2100. The clock format is configurable as a 12- (power-up

default) or 24-hour format, with an AM/PM indicator in the 12-hour mode. The RTC can be shut down

by clearing a bit in the clock register.

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