lm95172q National Semiconductor Corporation, lm95172q Datasheet - Page 17

• Manufacturer Part Number: lm95172q
• Description: Digital Temperature Sensor In Die Form With ?1?c Accuracy From 130?c To 160?c
• Manufacturer: National Semiconductor Corporation

1.7.3 Control/Status Register
(Read/Write) Pointer Address: 81h (Read); 01h (Write)
Bit <15>: Shutdown (SD) Bit. Writing a “1” to this bit and holding it high for at least the specified maximum conversion time, at the
existing temperature resolution setting, enables the Shutdown Mode. Writing a “0” to this bit restores the LM95172Q to normal
mode.
Bit <14>: One-Shot Bit. When in shutdown mode (Bit <15> is "1"), initates a single temperature conversion and update of the
temperature register with new temperature data. Has no effect when in continuous conversion mode (i.e., when Bit <15> is "0").
Always returns a "0" when read.
Bit <13>: OVERTEMP Reset Bit. Writing a "1" to this Bit resets the OVERTEMP Status bit and, after a possible wait up to one
temperature conversion time, the OVERTEMP pad. It will always return a "0" when read.
Bit <12>: Conversion Toggle Bit. Toggles each time the Control/Status register is read if a conversion has completed since the
last read. If conversion has not been completed, the value will be the same as last read.
Bit <11>: OVERTEMP pad Status Bit. This Bit is "0" when OVERTEMP output is low and "1" when OVERTEMP output is high.
The OVERTEMP output is reset under the following conditions: (1) Cleared by writing a "1" to the OVERTEMP Reset Bit (Bit <13>)
in this register or (2) Measured temperature falls below the T
Reset is set to "1", then the Bit and the pad clear until the next conversion, at which point the Bit and pad would assert again.
Bit <10>: Temperature High (T
in the programmable T
the programmed T
the status Bit remains set until it is read by the master so that the system can check the history of what caused the OVERTEMP
to assert.
Bit <9>: Temperature Low (T
in the programmable T
the programmed T
the T
OVERTEMP to assert.
Bit <8>: Data Available (DAV) Status Bit. This Bit is "0" when the temperature sensor is in the process of converting a new tem-
perature. It is "1" when the conversion is done. It is reset after each read and goes high again after one temperature conversion
is done. In one-shot mode: after initiating a temperature conversion while operating, this status Bit can be monitored to indicate
when the conversion is done. After triggering the one-shot conversion, the data in the temperature register is invalid until this Bit
is high (i.e., after completion of the first conversion).
Bit <7>: OVERTEMP Disable Bit. When set to "0" the OVERTEMP output is enabled. When set to "1" the OVERTEMP output is
disabled. This Bit also controls the OVERTEMP Status Bit (this register, Bit <11>) since that Bit reflects the state of the
OVERTEMP pad.
Bit <6>: OVERTEMP Polarity Bit. When set to "1", OVERTEMP is active-high. When "0" it is active-low.
Bit <5:4>: Temperature Resolution Bits. Selects one of four user-programmable temperature data resolutions as indicated in the
following table.
Bit <3>: Always write a zero to this Bit.
Bit <2:1>: Reserved Bits. Will return whatever was last written to them. Value is zero on power-up.
Bit <0>: Always write a zero to this Bit.
Reset State: 0000h
LOW
D15
OVERTEMP Disable
SD
limit, the status Bit remains set until it is read by the master so that the system can check the history of what caused the
One-Shot
D7
D14
HIGH
LOW
HIGH
LOW
limit and (2) upon reading the Control/Status Register. If the temperature no longer exceeds the T
limit and (2) upon reading the Control/Status Register. If the temperature is no longer below, or equal to,
OVERTEMP Reset
register. The flag is reset to "0" when both of two conditions are met: (1) temperature is no longer below
register. The flag is reset to "0" when both of two conditions are met: (1) temperature no longer exceeds
LOW
HIGH
OVERTEMP POL
) Flag Bit. This Bit is set to "1" when the measured temperature falls below the T
Reset Conditions: Upon Power-on Reset.
Bit 5
Control/Status Register
D13
) Flag Bit. This Bit is set to "1" when the measured temperature exceeds the T
0
0
1
1
D6
Conversion Toggle
Bit 4
0
1
0
1
RES1
D5
D12
LOW
17
limit. If the temperature is still above T
RES0
D4
Bits
13
14
15
16
OVERTEMP Status
Resolution
D3
0
0.0078125
D11
0.015625
0.03125
0.0625
°C
reserved
D2
T
D10
HIGH
reserved
D1
HIGH
T
, and OVERTEMP
D9
LOW
HIGH
LOW
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limit stored
DAV
D0
limit stored
D8
0
HIGH
limit,