10

100

1000

10000

CONVERSION TIME (ms)

0.0

0.25

0.5

0.75

1.0

1.25

1.5

1.75

2.0

LM95231

SNIS139E – FEBRUARY 2005 – REVISED MARCH 2013

www.ti.com

CONVERSION SEQUENCE

In the power up default state the LM95231 takes maximum a 77.5 ms to convert the Local Temperature, Remote

Temperature 1 and 2, and to update all of its registers. Only during the conversion process is the busy bit (D7) in

the Status register (02h) high. These conversions are addressed in a round robin sequence. The conversion rate

may be modified by the Conversion Rate bits found in the Configuration Register (03h). When the conversion

rate is modified a delay is inserted between conversions, the actual maximum conversion time remains at 87.7

ms. Different conversion rates will cause the LM95231 to draw different amounts of supply current as shown in

Figure 6.

Figure 6. Conversion Rate Effect on Power Supply Current

POWER-ON-DEFAULT STATES

LM95231 always powers up to these known default states. The LM95231 remains in these states until after the

first conversion.

1. Command Register set to 00h

2. Local Temperature set to 0°C until the end of the first conversion

3. Remote Diode Temperature set to 0°C until the end of the first conversion

4. Remote Diode digital filters are on.

5. Remote Diode 1 model is set to Pentium 4 processor on 90nm process with TruTherm mode enabled.

Remote Diode 2 model is set to 2N3904 with TruTherm mode disabled.

6. Status Register depends on state of thermal diode inputs

7. Configuration register set to 00h; continuous conversion, typical time = 85.8 ms when TruTherm Mode is

enabled for Remote 1 only

SMBus INTERFACE

The LM95231 operates as a slave on the SMBus, so the SMBCLK line is an input and the SMBDAT line is

bidirectional. The LM95231 never drives the SMBCLK line and it does not support clock stretching. According to

SMBus specifications, the LM95231 has a 7-bit slave address. All bits A6 through A0 are internally programmed

and can not be changed by software or hardware. The SMBus slave address is dependent on the LM95231 part

number ordered:

10

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