DS1629
The open-drain alarm output of the DS1629 will become active when either the measured temperature
exceeds the programmed over-temperature limit (T
H
) 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
1
2
3
4
5
6
7
8
SYMBOL
SDA
SCL
ALRM
GND
X
2
X
1
OSC
V
DD
DESCRIPTION
Data input/output pin
for 2-wire serial communication port.
Clock input/output pin
for 2-wire serial communication port.
Alarm output
Open drain time/temperature alarm output with configurable active
state
Ground pin.
32.768 kHz Feedback Output .
32.768 kHz Crystal input.
Oscillator Output.
Open-drain output used for microcontroller clock input.
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.
2.
3.
4.
5.
6.
Direct-to-digital temperature sensor
Real time clock
2-wire interface
Data registers
Thermal & clock alarm comparators
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.
2 of 22
102299
DALLAS [ DALLAS SEMICONDUCTOR ]
