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LM95071

SNIS137G – AUGUST 2004 – REVISED AUGUST 2019

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Table 1. Digital Output for Temperature

Data (continued)

Temperature

Digital Output

Binary

Hex

−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.

8.3.3 Tight Accuracy, Fine Resolution and Low Noise

The LM95071 is well suited for applications that require tight temperature measurement accuracy. In many

applications, from process control to HVAC, the low temperature error can mean better system performance and,

by eliminating a system calibration step, lower production cost.

With fine digital resolution, the LM95071 senses and reports very small changes in its temperature, making it

ideal for applications where temperature sensitivity is important. For example, the LM95071 enables the system

to quickly identify the direction of temperature change, allowing the processor to take compensating action before

the system reaches a critical temperature.

The LM95071 has very low output noise (see Figure 7 in the Typical Characteristics section), which makes it

ideal for applications where stable thermal compensation is a priority. For example, in a temperature-

compensated oscillator application, the very small deviation in successive temperature readings translates to a

stable frequency output from the oscillator.

8.4 Device Functional Modes

8.4.1 Shutdown Mode/Manufacturer ID

The master controller may enable the shutdown mode for the purpose of reducing power consumption or for

reading the Manufacturer/Device ID information. The shutdown mode is enabled by writing XX FF hex to the

LM95071 as shown in Figure 13c. The serial bus is still active when the LM95071 is in shutdown. When in

shutdown mode the LM95071 always will output 1000 0000 0000 1111. This is the Manufacturer/Device ID

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

8.5 Programming

8.5.1 Serial Bus Interface

The LM95071 operates as a slave and is compatible with SPI or MICROWIRE bus specifications. Data is clocked

out on the falling edge of the serial clock (SC), while data is clocked in on the rising edge of SC. A complete

communication is framed by falling and rising chip select (CS) signal. The CS signal should be held high for at

least one clock cycle (160 ns minimum) between communications. The transmit-only communication (register

read) consists of 16 clock cycles. A complete transmit/receive communication will consist of 32 serial clocks (see

Serial Bus Timing Diagrams). The first 16 clocks comprise the transmit phase of communication, while the

second 16 clocks are the receive phase.

When CS is high SI/O will be in TRI-STATE. Communication should be initiated by taking chip select (CS) low.

This should not be done when SC is changing from a low to high state. Once CS is low the serial I/O pin (SI/O)

will transmit the first bit of data. The master can then read this bit with the rising edge of SC. The remainder of

the data will be clocked out by the falling edge of SC. CS can be taken high at any time during the transmit

phase. If CS is brought low in the middle of a conversion the LM95071 will complete the conversion and the

output shift register will be updated after CS is brought back high.