JAJSFC6C May 2015 – April 2018 ADS52J90
PRODUCTION DATA.
A digital high-pass filter (HPF) can be enabled in the path of each ADC word. The enable control is shared between sets of four consecutive-numbered ADCs (ADC1-ADC4, ADC5-ADC8, ADC9-ADC12, and ADC13-ADC16). For example, DIG_HPF_EN_ADC1-4 enables the HPF in the paths of ADCOUT1, ADCOUT2, ADCOUT3, and ADCOUT4. The digital high-pass transfer function is determined by Equation 1:
When DIG_HPF_EN_ADC1-4 is set, the value of K in Equation 1 is set by the HPF_CORNER_ADC1-4 bits. The value of K can be programmed from 2 to 10. Table 9 shows the cutoff frequency as a function of K.
CORNER FREQUENCY (k)
(HPF_CORNER_ADCx Register) |
CORNER FREQUENCY (kHz) | ||
---|---|---|---|
fS = 40 MSPS | fS = 50 MSPS | fS = 65 MSPS | |
2 | 2780 | 3480 | 4520 |
3 | 1490 | 1860 | 2420 |
4 | 738 | 230 | 1200 |
5 | 369 | 461 | 600 |
6 | 185 | 230 | 300 |
7 | 111 | 138 | 180 |
8 | 49 | 61 | 80 |
9 | 25 | 30 | 40 |
10 | 12. | 15 | 20 |
By default the HPF output is truncated to 14 bits. To enable the rounding operation to map the HPF output to the ADC resolution, set the HPF_ROUND_EN_CH1-8 and HPF_ROUND_EN_CH9-16 bits to 1.