AD9213 datasheet(33/110 Pages) AD

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Data Sheet

AD9213

Rev. A | Page 33 of 110

TMU

The AD9213 contains a TMU that functions as a digital

thermometer. The TMU is comprised of five sensors placed at

different chip locations. The on-die temperature value is

measured and digitized through an ADC.

At any given time, the value from the sensor with the highest

temperature is stored in Register 0x1609, Bits[7:0] and

16-bit maximum temperature word. Similarly, the value from

the sensor with the lowest temperature is stored in

these values combine to give a 16-bit minimum temperature

word.

The nine MSBs of each 16-bit temperature word are the integer

portion of the die temperature in twos complement. The seven

LSBs represent the fractional portion of the temperature, that is,

the digits to the right of the decimal place. For example, the

most significant of the seven LSBs represents 2−1 and the next

bit to the right is 2−2.

The following procedure is an example of obtaining the value of

the sensor that produces the highest temperature reading. The

procedure to reading the minimum temperature is the same as the

procedure to read the maximum temperature, but with different

read.

To obtain the maximum temperature, read Register 0x1609

(maximum temperature word containing the eight LSBs) and

eight MSBs).

For example,

1. Register 0x1609 = 0x76 = 01110110b.

2. Register 0x160A = 0x2C = 00101100b.

3. Concatenate the MSBs to the LSBs to give a 16-bit word:

4. The nine MSBs of this word represent the twos

complement integer value of the temperature in degrees

Celsius:

001011000 (twos complement) = 88 (decimal).

5. The seven LSBs of the 16-bit word are the fractional

portion where the most significant (left most) bit value is

2−1, the next is 2−2, and so on. Using this convention,

1110110 = 0.92188 (decimal).

Therefore, the die temperature reported by the highest reading

sensor is 88°C + 0.92188°C = 88.92188°C. The accuracy of the

TMU is typically ±2°C, and the fractional portion of the

temperature value has limited significance.

Table 9. TMU Register Summary

Address

Bits Description

Reset Access

0x1609

MAX_TEMPERATURE_LSB [7:0] Bits[7:0] of maximum temperature of all temperature sensors. Q9.7 format.

0x0

0x160A

MAX_TEMPERATURE_MSB [7:0] Bits[15:8] of maximum temperature of all temperature sensors. Q9.7 format. 0x0

0x160D

MIN_TEMPERATURE_LSB

[7:0] Bits[7:0] of minimum temperature of all temperature sensors. Q9.7 format.

0x0

0x160E

MIN_TEMPERATURE_MSB [7:0] Bits[15:8] of minimum temperature of all temperature sensors. Q9.7 format.

0x0

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