Datasheet

LM95172
www.ti.com SNOSB33B –DECEMBER 2009–REVISED MARCH 2013
Table 4. 16-Bit Resolution. First bit (D15) is Sign and the last bit (D0) is the LSB.
16-bit Resolution Digital Output
Temperature All 16 Bits
16-bit Binary
Hex
+175°C 0101 0111 1000 0000 5780
+150°C 0100 1011 0000 0000 4B00
+80°C 0010 1000 0000 0000 2800
+25°C 0000 1100 1000 0000 0C80
+0.0078125°C 0000 0000 0000 0001 0001
0°C 0000 0000 0000 0000 0000
−0.0078125°C 1111 1111 1111 1111 FFFF
−40°C 1110 1100 0000 0000 EC00
The first data byte is the most significant byte with most significant bit first, permitting only as much data as
necessary to be read to determine temperature condition. For instance, if the first four bits of the temperature
data indicate an overtemperature condition, the host processor could immediately take action to remedy the
excessive temperatures.
SHUTDOWN MODE
Shutdown Mode is enabled by writing a “1” to the Shutdown Bit, Bit 15 of the Control/Status Register, and
holding it high for at least the specified maximum conversion time at the existing temperature resolution setting.
(see Temperature Conversion Time specifications under the Temperature-to-Digital Converter Characteristics).
For example, if the LM95172EWG is set for 16-bit resolution before shutdown, then Bit 15 of the Control/Status
register must go high and stay high for the specified maximum conversion time for 16-bits resolution.
The LM95172EWG will always finish a temperature conversion and update the temperature registers before
shutting down.
Writing a “0” to the Shutdown Bit restores the LM95172EWG to normal mode.
INTERNAL REGISTER STRUCTURE
The LM95172EWG has four registers that are accessible by issuing a command byte (a R/W Bit plus the register
address: Control/Status, T
HIGH
, T
LOW
, and Identification. Which of these registers will be read or written is
determined by the Command Byte. See COMMUNICATING WITH THE LM95172EWG for a complete
description of the serial communication protocol. The following diagram describes the Command Byte and lists
the addresses of the various registers. On power-up, the Command Byte will point to the Temperature Register
by default. The temperature is read by lowering the CS line and then reading the 16-Bit temperature register; all
other registers are accessed by writing a Command Byte after reading the temperature.
All registers can be communicated with, either in Continuous Conversion mode or in Shutdown mode. When the
LM95172EWG has been placed in Shutdown Mode, the Temperature register will contain the temperature data
which resulted from the last temperature conversion (whether it was the result of a continuous-conversion
reading or a one-shot reading).
Command Byte
P7 P6 P5 P4 P3 P2 P1 P0
R/W 0 0 0 0 Register Select
Bit <7> Read/Write Bit. Tells the LM95172EWG if the host will be writing to, or reading from, the register to which
this byte is pointing.
Bits <6:3> Not Used. These Bits must be zero. If an illegal address is written, the LM95172EWG will return
0000h on the subsequent read.
Bits <2:0> Pointer Address Bits. Points to desired register. See table below.
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