I installed 2x LTC6811-2 and then 1x LTC6804-2 on the same board and I don't have any voltage reference output at anytime. The functional diagram in the datasheets shows that VREF1 should be always present as it's generated from V+. VREF2 is not sure what generates it.
On my board, which is a copy paste of the application note of the LTC6811 (DC2560A), no reference output is present.
DRIVE is at 5.8V, VREG is at 5V, V+ is from 10V to 30V, and there is no answer from the LTC6811.
How can I probe that this is not an internal failure of the LTC6811/LTC6804 ? I it possible to check VREGD ?
What would cause 3 new parts to fail just after installation ? ESD protected area is being used.
thanks. Yes, indeed, there is a 5kOhm pull-up on MISO and it has been checked (solder joint, trace, value)
What is really weird, is that, in some cases, after extensive testing and probing, the SPI communication seems to work. I noticed that this happened twice when I shorted inadvertently MISO and MOSI. MISO becomes active, references are set at the right value ... even if the data-stream is not as expected (all value at stuck at 6.35V on the Linduino program).
I'm having this same exact issue with the LTC6813 as well. The SPI communications work and a valid PEC is received always, however, the values themselves are 6.5535V and the REF voltages are always at 0V.