lm95172qa2 National Semiconductor Corporation, lm95172qa2 Datasheet - Page 12

• Manufacturer Part Number: lm95172qa2
• Description: 13-bit To 16-bit Digital Temperature Sensor With 3-wire Interface
• Manufacturer: National Semiconductor Corporation

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1.2 ONE SHOT CONVERSION
The LM95172QA2 MDA features a one-shot conversion bit,
which is used to initiate a singe conversion and comparison
cycle when the LM95172QA2 MDA is in shutdown mode.
While the LM95172QA2 MDA is in shutdown mode, writing a
"1" to the One-Shot bit in the Control/Status Register will
cause the LM95172QA2 MDA to perform a single tempera-
ture conversion and update the Temperature Register and the
affected status bits. Operating the LM95172QA2 MDA in this
one-shot mode allows for extremely low average-power com-
sumption, making it ideal for low-power applications.
When the One-shot bit is set, the LM95172QA2 MDA initiates
a temperature conversion. After this initiation, but before the
completion of the conversion, and resultant register updates,
the LM95172QA2 MDA is in a "one-shot" state. During this
state, the Data Available (DAV) flag in the Control/Status
Register is "0" and the Temperature Register contains the
The OVERTEMP Output will assert when the measured tem-
perature is greater than the T
reset if any of the following events happen:
1. The temperature falls below the value stored in the T
register, or
2. A "1" is written to the OVERTEMP Reset bit in the Control/
Status Register.
FIGURE 11. LM95172QA2 MDA OVERTEMP vs. Temperature Response Diagram
HIGH
value. OVERTEMP will
LOW
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value 8000h (-256°C). All other registers contain the data that
was present before initiating the one-shot conversion. After
the temperature measurement is complete, the DAV flag will
be set to "1" and the temperature register will contain the re-
sultant measured temperature.
1.3 OVERTEMP OUTPUT
The Over-temperature (OVERTEMP) output is a temperature
switch signal that indicates when the measured temperature
exceeds the T
T
register is used to set the hysteresis. The T
sets the temperature below which the OVERTEMP output re-
sets. The OVERTEMP output of the LM95172QA2 MDA be-
haves as a temperature comparator. The following explains
the operation of OVERTEMP. Figure 9 illustrates the
OVERTEMP output behavior.
If OVERTEMP is cleared by the master writing a "1" to the
OVERTEMP Reset bit while the measured temperature still
exceeds the T
the completion of the next temperature conversion. Placing
the LM95172QA2 MDA in shutdown mode or triggering a one-
shot conversion does not cause OVERTEMP to reset.
HIGH
register sets the high temperature limit and the T
HIGH
HIGH
value, OVERTEMP will assert again after
programmed limit. The programmable
30035721
LOW
register also
LOW