SPRUJ55D September 2023 – July 2025 AM263P2 , AM263P2-Q1 , AM263P4 , AM263P4-Q1
Based on a given ADC conversion result, the corresponding analog input is given in Table 7-114 and Table 7-115. This corresponds to the center of the possible range of analog voltages that can produce this conversion result.
| Digital Value | Analog Equivalent |
|---|---|
| when ADCRESULTy = 0 | Equation 2.
|
| when 0 < ADCRESULTy < 4095 | Equation 3.
|
| when ADCRESULTy = 4095 | Equation 4.
|
The ADC can be operated in either single-ended or differential mode; the inputs can be configured according to Table 7-115.
| chsel_1p1v<2:0> | diff_mode_1p1v=1 | diff_mode_1p1v=0 |
|---|---|---|
| 000 | inp=ch0, inm=ch1 | ch0 |
| 001 | inp=ch1, inm=ch0 | ch1 |
| 010 | inp=ch2, inm=ch3 | ch2 |
| 011 | inp=ch3, inm=ch2 | ch3 |
| 100 | inp=ch4, inm=ch5 | ch4 |
| 101 | inp=ch5, inm=ch4 | ch5 |
| 110 | inp=cal0, inm=cal1 | cal0 |
| 111 | inp=cal1, inm=cal0 | cal1 |
Single-ended Mode:
The ADC is designed for 12-bit output, but internally the ADC generates slightly more than 12 bits. There are certain modes that can be selected utilizing bits adcX_cfg_1p1v<80:79> to clip and shift the ADC output to utilize different regions in SE (single-ended) mode. The default mode (00) clips the output within 0 and 4095 to maintain a 12-bit value; this effectively limits the maximum input of the ADC to 3.2V. In the shifted mode (01), the ADC effectively shifts the input so that the ADC creates a 12-bit output between 0.1V and 3.3V.
| Input | Output (adcX_cfg_1p1v<80:79>) | ||
|---|---|---|---|
| Equation | Input Voltage | Raw O/P | Default(00) |
| 3.3/4224 * 0 | 0 | 0 | 0 |
| 3.3/4224 * 1 | 0.00078125 | 1 | 1 |
| 3.3/4224 * 2 | 0.0015625 | 2 | 2 |
| ... | ... | ... | ... |
| 3.3/4224 * 127 | 0.09921875 | 127 | 127 |
| 3.3/4224 * 128 | 0.1 | 128 | 128 |
| 3.3/4224 * 129 | 0.10078125 | 129 | 129 |
| ... | ... | ... | ... |
| 3.3/4224 * 4094 | 3.1984375 | 4094 | 4094 |
| 3.3/4224 * 4095 | 3.19921875 | 4095 | 4095 |
| 3.3/4224 * 4096 | 3.2 | 4096 | 4095 |
| ... | ... | ... | ... |
| 3.3/4224 * 4221 | 3.29765625 | 4221 | 4095 |
| 3.3/4224 * 4222 | 3.2984375 | 4222 | 4095 |
| 3.3/4224 * 4223 | 3.29921875 | 4223 | 4095 |
Differential Mode:
In differential mode ADC output code can be estimated using the following equation:
ADC Output Code = floor((VinpX-VinmX)/step_size + 2112)
Where step_size = (VrefP-VrefM) * 33/18/4224
Note the addition factor is 2112 as the ADC generates a full-scale code in raw o/p mode as 4223. This 64-LSB shift can be compensated if adcX_cfg_1p1v<80:79> is set to (01) in differential mode
The adcX_cfg_1p1v<80:79> is not normally accessible, but can be overwritten by following the below steps. The bits in this and surrounding registers are critical for ADC functionality. Care must be taken so that only the bits <80:79> are changed as desired, while remaining bits remain in the default programmed state.