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

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.

Copyright © 2009–2013, Texas Instruments Incorporated

Submit Documentation Feedback

13

Product Folder Links: LM95172