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# 3.3.4.58 EMAFE_ADCGGetVREFLowTemp Function

## C

    uint16_t EMAFE_ADCGGetVREFLowTemp ( void );

## Summary

Get the Voltage Reference at low temperature.

## Description

An on-die analog voltage reference provides a typical output voltage of INT_REF_VOLTAGE V. The temperature drift of the voltage reference can be approximated by a linear fit. For H-grade parts, the temperature drift is measured during manufacturing and stored in the calibration registers (ROM). Two measurements are made: one at a low temperature, TL, and another at a high temperature, TH. At both temperatures TL and TH, VREF_AFE voltage and ADC_TEMP_OUT (reading of the temperature sensor by ADC Channel 0) parameters are saved. From the data obtained, the user can implement a software compensation of the voltage reference.

## Precondition

None.

## Parameters

None.

## Returns

Voltage Reference value at low temperature.

## Example

    uint16_t vRefLowTemp = EMAFE_ADCGGetVREFLowTemp();

## Remarks

For H-grade products, it is possible to compensate the drift of the voltage reference by using the calibration registers described above. The following formula is used to estimate VREF_AFE at a given temperature.
Figure 3-28.Correction Algorithm
where:

- TEMP_TL = EMAFE_ADCGGetTEMPLowTemp() [signed 12-bit integer]
- TEMP_TH = EMAFE_ADCGGetTEMPHighTemp() [signed 12-bit integer]
- REF_TL = EMAFE_ADCGGetVREFLowTemp() [signed 12-bit integer]
- REF_TH = EMAFE_ADCGGetVREFHighTemp() [signed 12-bit integer]
- VREF_AFE(TL) = INT_REF_VOLTAGEV + REF_TL * 25 μV
- VREF_AFE(TH) = INT_REF_VOLTAGEV + REF_TH * 25 μV
- ADC_TEMP_OUT(TL) = TEMP_TL << 12
- ADC_TEMP_OUT(TH) = TEMP_TH << 12
- VREF_AFE(ADC_TEMP_OUT) = Estimated VREF_AFE value when the temperature sensor reading is ADC_TEMP_OUT

Rev: E