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ADT7312

Data Sheet

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TEMPERATURE DATA FORMAT

One LSB of the ADC corresponds to 0.0078°C in 16-bit mode.

The ADC can theoretically measure a temperature range of

255°C, but the ADT7312 is guaranteed to measure a low value

temperature limit of −55°C to a high value temperature limit of

+175°C. The temperature measurement result is stored in the

16-bit temperature value register (Register Address 0x02). It is

compared with the high temperature limits stored in the TCRIT

setpoint register and the THIGH setpoint register. The temperature

measurement result is also compared with the low temperature

limit stored in the TLOW setpoint register.

Temperature data in the temperature value register, the TCRIT

setpoint register, the THIGH setpoint register, and the TLOW setpoint

MSB is the temperature sign bit. When the part is powered up, the

three LSBs, Bits[2:0], are not part of the temperature conversion

result, but are flag bits for TCRIT, THIGH, and TLOW. Table 6 shows

the 13-bit temperature data format without Bits[2:0].

Table 6. 13-Bit Temperature Data Format

Temperature

Digital Output (Bits[D15:D3])

Binary

Hex

−55°C

1 1100 1001 0000

0x1C90

−50°C

1 1100 1110 0000

0x1CE0

−25°C

1 1110 0111 0000

0x1E70

−0.0625°C

1 1111 1111 1111

0x1FFF

0°C

0 0000 0000 0000

0x0000

+0.0625°C

0 0000 0000 0001

0x0001

+25°C

0 0001 1001 0000

0x0190

+50°C

0 0011 0010 0000

0x0320

+125°C

0 0111 1101 0000

0x07D0

+150°C

0 1001 0110 0000

0x0960

+175°C

0 1010 1111 0000

0x0AF0

The number of bits in the temperature data-word can be

extended to 16 bits, twos complement, by setting Bit 7 of the

configuration register (Register Address 0x01) to 1. When using

a 16-bit temperature data value, Bits[2:0] are the LSBs of the

temperature value. The default power-on configuration is a

13-bit temperature data value.

Reading back the temperature from the temperature value

erature data format can still use the ADT7312 by ignoring the

four LSBs of the 13-bit temperature value. These four LSBs are

Bits[6:3] in Table 6.

TEMPERATURE CONVERSION FORMULAS

16-Bit Temperature Data Format

Positive Temperature = ADC Code (dec)/128

Negative Temperature = (ADC Code (dec) − 65,536)/128

where ADC Code uses all 16 bits of the data byte, including the

sign bit.

Negative Temperature = (ADC Code (dec) − 32,768)/128

where the MSB is removed from the ADC code.

13-Bit Temperature Data Format

Positive Temperature = ADC Code (dec)/16

Negative Temperature = (ADC Code (dec) − 8192)/16

where ADC Code uses all 13 bits of the data byte, including the

sign bit.

Negative Temperature = (ADC Code (dec) − 4096)/16

where the MSB is removed from the ADC code.

10-Bit Temperature Data Format

Positive Temperature = ADC Code (dec)/2

Negative Temperature = (ADC Code (dec) − 1024)/2

where ADC Code uses all 10 bits of the data byte, including the

sign bit.

Negative Temperature = (ADC Code (dec) − 512)/2

where the MSB is removed from the ADC code.

9-Bit Temperature Data Format

Positive Temperature = ADC Code (dec)

Negative Temperature = ADC Code (dec) − 512

where ADC Code uses all nine bits of the data byte, including

the sign bit.

Negative Temperature = ADC Code (dec) − 256

where the MSB is removed from the ADC code.

Rev. A

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