ADT75 datasheet(12/25 Pages) AD

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Data Sheet

ADT75

Rev. B | Page 11 of 24

Configuration register functions consist of

•

Switching between normal operation and full power-down.

•

Switching between comparator and interrupt event modes.

•

Setting the OS/ALERT pin active polarity.

•

Setting the number of faults that activate the OS/ALERT pin.

•

Enabling the one-shot mode.

•

Enabling the SMBus alert function mode on the

OS/ALERT pin.

TEMPERATURE DATA FORMAT

One LSB of the ADC corresponds to 0.0625°C. The ADC can

theoretically measure a temperature range of 255°C (−128°C to

+127°C ), but the ADT75 is guaranteed to measure a low value

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

+125°C. The temperature measurement result is stored in the

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

temperature limit stored in the TOS setpoint register and the

hysteresis limit in the THYST setpoint register.

Temperature data in the temperature value register, the TOS

setpoint register and the THYST setpoint register, is represented

by a 12-bit twos complement word. The MSB is the temperature

sign bit. The four LSBs, Bit DB0 to Bit DB3, are not part of the

temperature conversion result and are always 0s. Table 6 shows

the temperature data format without Bit DB0 to Bit DB3.

Reading back the temperature from the temperature value

is required, then a 1-byte read is required. Designers that use a

9-bit temperature data format can still use the ADT75 by ignoring

the last three LSBs of the 12-bit temperature value. These three

LSBs are Bit D4 to Bit D6 in Table 6.

Table 6. 12-Bit Temperature Data Format

Temperature

Digital Output (Binary)

DB15 to DB4

Digital Output (Hex)

−55°C

1100 1001 0000

0xC90

−50°C

1100 1110 0000

0xCE0

−25°C

1110 0111 0000

0xE70

−0.0625°C

1111 1111 1111

0xFFF

0°C

0000 0000 0000

0x000

+0.0625°C

0000 0000 0001

0x001

+10°C

0000 1010 0000

0x0A0

+25°C

0001 1001 0000

0x190

+50°C

0011 0010 0000

0x320

+75°C

0100 1011 0000

0x4B0

+100°C

0110 0100 0000

0x640

+125°C

0111 1101 0000

0x7D0

Temperature Conversion Formulas

12-Bit Temperature Data Format

•

Positive Temperature = ADC Code(d)/16

•

Negative Temperature = (ADC Code(d)1− 4096)/16, or

Negative Temperature = (ADC Code(d)2 – 2048)/16

9-Bit Temperature Data Format

•

Positive Temperature = ADC Code(d)/2

•

Negative Temperature = (ADC Code(d)3 – 512)/2, or

Negative Temperature = (ADC Code(d)4 – 256)/2

8-Bit Temperature Data Format

•

Positive Temperature = ADC Code(d)

•

Negative Temperature = ADC Code(d)5 – 256, or Negative

Temperature = ADC Code(d)6 – 128

Bit DB7 (sign bit) is removed from the ADC code.

1 For ADC code, use all 12 bits of the data byte, including the sign bit.

2 For ADC code, Bit DB11 (sign bit) is removed from the ADC code.

3 For ADC code, use all 9 bits of the data byte, including the sign bit.

4 Bit DB8 (sign bit) is removed from the ADC code.

5 For the ADC code, use all 8 bits of the data byte, including the sign bit.

6 Bit DB7 (sign bit) is removed from the ADC code.

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