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TPCE636 User Manual Issue 1.0.2
Page 56 of 104
7.8.3.1 I2C Calibration Data
There are two errors affecting the accuracy of the ADC and DAC that can be corrected using the factory
calibrated calibration data. The correction values are obtained during factory calibration and are stored in an
on-board I2C EEPROM as 2-complement 16bit values in the range from -32768 to +32767. To achieve a
higher accuracy, they are scaled to ¼LSB.
DAC Offset Error:
For the DAC, this is the data value that is required to produce a zero voltage output signal. This error is
corrected by subtracting the offset from the DAC data value.
ADC Offset Error:
The offset error is the data value when converting with the input connected to its own ground in single-ended
mode, or with shorted inputs in differential mode. This error is corrected by subtracting the known error from
the reading.
DAC Gain Error:
The gain error is the difference between the ideal gain and the actual gain of the DAC. It is corrected by
multiplying the DAC data value with a correction factor.
ADC Gain Error:
The gain error is the difference between the ideal gain and the actual gain of the programmable gain
amplifier and the ADC. This error is corrected by multiplying the reading with a correction factor.
7.8.3.2 ADC and DAC Calibration Data Values
The 16 ADC channels are realized with eight dual LTC2323-16 ADC devices.
For each ADC channel a 16bit Offset correction and a 16bit gain correction value is stored.
I2C EEPROM
Address
Description
Size
(Bit)
0x000
ADC Channel 1 Offset
corr
High Byte
8
0x001
ADC Channel 1 Offset
corr
Low Byte
8
0x002
ADC Channel 1 Gain
corr
High Byte
8
0x003
ADC Channel 1 Gain
corr
Low Byte
8
…
0x03C
ADC Channel 16 Offset
corr
High Byte
8
0x03D
ADC Channel 16 Offset
corr
Low Byte
8
0x03E
ADC Channel 16 Gain
corr
High Byte
8
0x03F
ADC Channel 16 Gain
corr
Low Byte
8
Table 7-12: ADC Calibration Data Values