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AD7124 internal temperature sensor

Question asked by vangelov61 on Apr 27, 2017
Latest reply on Apr 28, 2017 by vangelov61

Hi,

I'm trying to use the internal temperature sensor in AD7124-4. In the datasheet one can find only this description:

 

TEMPERATURE SENSOR
Embedded in the AD7124-4 is a temperature sensor that is useful to monitor the die temperature. This is selected using the
AINP[4:0] and AINM[4:0] bits in the channel register. The sensitivity is 13,584 codes/°C, approximately. The equation for
the temperature sensor is
Temperature (°C) = ((Conversion − 0x800000)/13,584) − 272.5

 

I tried to connect AINP to Temperature Sensor (16) and AINM to AVSS or DGND. So I get for the Channel_5 register 0xB211 (using Setup 3, because the others are used for other inputs). In Config_3 I have PGA=1 (but it doesn't matter), REF_SEL=Int_Ref, all Buf=Off. Burnout=off, Bipolar, so Config_3 = 0x810. When using the expression from the datasheet, I get (at room temperature) temperatures of 2-3 °C after power up and about 9°C after some minutes.

 

I hope somebody has already used the temperature sensor in the ADC and will post here the settings.

Sincerely yours,

V.Angelov

 

The registers in AD7124-4 with values different from the reset values are:

Addr             Name    R-Data Init-Value Type

0x01       ADC_Control   0x0582    0x0000   R/W
0x07          Error_En   0x000040  0x000044 R/W
0x09         Channel_0   0x8020    0x8001   R/W
0x0a         Channel_1   0x8060    0x0001   R/W
0x0b         Channel_2   0x9051    0x0001   R/W
0x0c         Channel_3   0x9091    0x0001   R/W
0x0d         Channel_4   0xa0d1    0x0001   R/W
0x0e         Channel_5   0xb211    0x0001   R/W
0x19          Config_0   0x0871    0x0860   R/W
0x1a          Config_1   0x0051    0x0860   R/W
0x1b          Config_2   0x0050    0x0860   R/W
0x1c          Config_3   0x0810    0x0860   R/W
0x21          Filter_0   0xa60280  0x060180 R/W
0x22          Filter_1   0xa60280  0x060180 R/W
0x23          Filter_2   0xa60280  0x060180 R/W
0x24          Filter_3   0xa60280  0x060180 R/W

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