Rainbow Electronics DS1629 - Manual (Page 4)

DS1629
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DS1629 FUNCTIONAL BLOCK DIAGRAM Figure 1
OPERATION-Measuring Temperature
The DS1629 measures temperature through the use of an on-chip temperature measurement technique
with an operating range from -55
°
C to +125
°
C. The device can be configured to perform a single
conversion, store the result, and return to a standby mode or it can be programmed to convert
continuously. Regardless of the mode used, the last completed digital temperature conversion is retrieved
from the temperature register using the Read Temperature (AAh) protocol, as described in detail in the
“Command Set” section. Details on how to change the settings after power-up are contained in the
“OPERATION-Configuration” section.
The DS1629 measures temperature by counting the number of clock cycles that an oscillator with a low
temperature coefficient goes through during a gate period determined by a high temperature coefficient
oscillator. The counter is preset with a base count that corresponds to -55
°
C. If the counter reaches 0
before the gate period is over, the temperature register, which is also preset to the -55
°
C value, is
incremented, indicating that the temperature is higher than -55
°
C.