SPRZ579A July 2025 – October 2025 F28E120SB , F28E120SC
ADC: Degraded ADC Performance With ADCCLK Fractional Divider
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Using fractional SYSCLK-to-ADCCLK dividers (controlled by the ADCCTL2.PRESCALE field) has been shown to cause degradation in ADC performance on this device. See Table 3-1.
| REDUCED PERFORMANCE | |||
|---|---|---|---|
| BIT | FIELD | VALUE | DESCRIPTION |
| 3–0 | PRESCALE | 0001 | ADCCLK = SYSCLK/1.5 |
| 0003 | ADCCLK = SYSCLK/2.5 | ||
| ... | |||
| NORMAL PERFORMANCE | |||
| BIT | FIELD | VALUE | DESCRIPTION |
| 3–0 | PRESCALE | 0000 | ADCCLK = SYSCLK/1.0 |
| 0002 | ADCCLK = SYSCLK/2.0 | ||
| ... | |||
Use even PRESCALE clock divider values. Even PRESCALE values result in integer clock dividers which do not impact the ADC performance.