Hello, I meet some problem of my ADS8556EVM. The thing is, the ADC doesn´t allow us to supply its digital part with a +3.3V.
Here is our configuration,
For the power supply part J3 on EVM, we are supplying pin J3.1and J3.2 with +12V and -12V seperately and the ground of them goes to J3.6 AGND. Also, we are supplying another +5V on J3.3 AVdd, with its ground to J3.6 AGND. For the digital supply, we also supply a +3.3V for J3.9 BVDD with its ground to J3.5 BGND. Besides, the jumper JP4 is placed on the 3.3V side. Of course, all these supplies are well regulated and isolated.
We are working in parallel mode, and we want to measure a simple sinusoidal input voltage (Of course lying inside the measurement range).
The weird thing is, when we try to supply J3.9 with a +3.3V, the ADC doesn´t work at all even after trying to toggle the RESET pin 1.1. With the start of conversion signal giving to the ADC, there is no BUSY signal showing. Amazingly, when we remove the digital supply on J3.9(+3.3V), the ADC can convert and the data we read through a DSP is as expected. Only the ADC gets into power down mode so frequently. And also we checked the test point for BVdd, it is 0.
We are wondering why without the supply for the digital part, the adc can still converter data. And what should we do to provide this +3.3V?
