ADT7310 datasheet(13/24 Pages) AD

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ADT7310

Rev. 0 | Page 13 of 24

TEMPERATURE DATA FORMAT

One LSB of the ADC corresponds to 0.0625°C in 13-bit mode.

The ADC can theoretically measure a temperature range of

255°C, but the ADT7310 is guaranteed to measure a low value

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

of +150°C. The temperature measurement result is stored in

the 16-bit temperature value register and is compared with the

high temperature limits stored in the TCRIT setpoint register and

the THIGH setpoint register. It 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 register are represented by a 13-bit twos complement

word. The MSB is the temperature sign bit. The three LSBs,

Bit 0 to Bit 2, on power-up, are not part of the temperature

conversion result and are flag bits for TCRIT, THIGH, and TLOW.

Table 5 shows the 13-bit temperature data format without

Bit 0 to Bit 2.

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

extended to 16 bits, twos complement, by setting Bit 7 to 1

in the configuration register (Register Address 0x01). When

using a 16-bit temperature data value, Bit 0 to Bit 2 are not

used as flag bits and are instead the LSB bits of the temperature

value. The power-on default setting has a 13-bit temperature

data value.

Reading back the temperature from the temperature value register

requires a 2-byte read. Designers that use a 9-bit temperature

data format can still use the ADT7310 by ignoring the last four

LSBs of the 13-bit temperature value. These four LSBs are Bit 3

to Bit 6 in Table 5.

Table 5. 13-Bit Temperature Data Format

Temperature

Digital Output

(Binary) Bits[

15:3]

Digital

Output (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

0x000

+0.0625°C

0 0000 0000 0001

0x001

+25°C

0 0001 1001 0000

0x190

+50°C

0 0011 0010 0000

0x320

+125°C

0 0111 1101 0000

0x7D0

+150°C

0 1001 0110 0000

0x960

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.

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