Hi there,
We're currently trying to get a ADS5232 working using the ADS5332EVM evaluation board. The issue is that, despite connecting everything as suggested in the user guide, the 3.3V power supply seems to be a near short to ground.
We have two boards, both connected as follows:
- 5V differential power supply: disconnected.
- 3.3V analog supply: connected to a bench supply channel A.
- 3.3V output buffer supply: connected to bench supply channel B.
- Clock input: connected to a square wave bench source.
- Analog input A: grounded.
- Analog input B: disconnected.
- Jumpers: All in their 'default' positions, as listed in the user guide Table 1.
- Everything else: disconnected.
On board #1, connecting the output buffer supply does not draw much/any current. Once the analog supply is connected, the bench supply goes into current limiting mode, shorting the power line. If I allow it, it will draw ~2A, the current rating of the power supply.
On board #2, it's the opposite. Connecting the analog supply doesn't draw much, but connecting the output buffer supply draws ~800mA. Note that it doesn't draw more than 800mA if I turn the current limit higher than that.
In both cases the ADC chips get very hot if I allow the current to flow.
I've checked for obvious assembly defects, solder shorts, etc., but I can't find any. It's possible there is a short under a chip or internal to the PCB. I did a 2-wire measurement of the terminal impedance:
(Analog terminals / Output buffer terminals)
Board 1: ~0.7Ohm / ~440Ohm.
Board 2: ~440Ohm / ~45MOhm.
On one hand, it seems quite clear that there is a short somewhere, at least on board#1. However, that doesn't explain why board #2 behaves like a short even though the impedance is so high. Perhaps I'm missing something really simple, since it seems unlikely to me that two boards would both have a manufacturing error of the same/similar kind. I would appreciate any help you guys have to offer in debugging this issue.
