Datasheet

LM71, LM71-Q1

www.ti.com

SNIS125D –MARCH 2004–REVISED MARCH 2013

TEMPERATURE DATA FORMAT

Temperature data is represented by a 14-bit, two's complement word with an LSB (Least Significant Bit) equal to

0.03125°C:

Digital Output

Temperature

Binary Hex

+150°C 0100 1011 0000 0011 4B03

+125°C 0011 1110 1000 0011 3E83

+25°C 0000 1100 1000 0011 0C83

+0.03125°C 0000 0000 0000 0111 0007

0°C 0000 0000 0000 0011 0003

−0.03125°C 1111 1111 1111 1111 FFFF

−25°C 1111 0011 1000 0011 F383

−40°C 1110 1100 0000 0011 EC03

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/MANUFACTURER'S ID

Shutdown mode is enabled by writing XX FF to the LM71 as shown in Figure 13. The serial bus is still active

when the LM71 is in shutdown. When in shutdown mode the LM71 always will output 1000 0000 0000 1111. This

is the manufacturer's/Device ID information. The first 5-bits of the field (1000 0XXX) are reserved for

manufacturer's ID.

INTERNAL REGISTER STRUCTURE

The LM71 has three registers, the temperature register, the configuration register and the manufacturer's/device

identification register. The temperature and manufacturer's/device identification registers are read only. The

configuration register is write only.

Configuration Register

(Selects shutdown or continuous conversion modes):

Table 1. (Write Only):

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

X X X X X X X X Shutdown

D0–D15 set to XX FF hex enables shutdown mode.

D0–D15 set to 00 00 hex sets Continuous conversion mode.

Note: setting D0-D15 to any other values may place the LM70 into a manufacturer's test mode, upon which the

LM71 will stop responding as described. These test modes are to be used for TI production testing only. See

SERIAL BUS INTERFACE for a complete discussion.

Product Folder Links: LM71 LM71-Q1