JAJSEC1C November 2019 – July 2020 ADS8686S
PRODUCTION DATA
The ADS8686S has two independent power supplies, AVDD and DVDD. The AVDD supply provides power to the ADC and the analog circuits. The DVDD supply provides power to the digital interface. The AVDD and DVDD supplies can be set independently to voltages within the permissible range. Decouple both the AVDD and the DVDD supply with a 10-µF capacitor in parallel with a 100-nF capacitor.
Figure 9-1 shows the effect of using the recommended decoupling capacitor on the power-supply rejection ratio (PSRR) performance of the device.
The ADS8686S generates the additional required supplies using the internal LDO regulators. Decouple the analog LDO (ALDO) with a 10-µF capacitor between the REGCAP and REGGND pins. Decouple the digital LDO (DLDO) with a 10-µF capacitor between the REGCAPD and REGGNDD pins.
The ADS8686S is robust to power-supply sequencing (that is, the AVDD and DVDD can be powered up in random order). The recommended sequence is to power up DVDD first, followed by AVDD. Hold RESET low until both supplies are stabilized.