Hi,
we've been using TLV2556 in a plethora of designs and for many years.
Only recently a couple of boards appeared where the ADC does not seem to work. Right from the power-up the converter seems to pick an arbitrary value and constantly keeps returning it, regardless of the selected channel or the voltage applied.
As shown in the traces the converter is alternatingly set up (CFGR2 - 0xFE00 = external reference and /INT output) and then a channel ought to be converted (0x0C00, 0x1C00 etc.). The clock already is rather slow, some 2MHz or so, and there is plenty of setup and hold around the chip select.
When I further reduce the clock to about 500kHz then sometimes I can get the converter to work.
(Edit:) What, however, strikes me is that /INT goes low almost immeadiately after the final (16th) falling clock edge, i.e. immediately after the conversion starts. I'd have expected a delay of around 4µs to cover the conversion time itself.
What's wrong here?
Kind regards,
Sven
