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LTC6804-2 and LTC6811-2 reference voltage 1 and 2 at 0V.

Hello,

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.

Parents
  • The part is powering up correctly from what you indicate, and the parts with Drive=5.6V are awake as well. Is there a pullup on the SDO (assuming normal SPI connection)? If not there will be no MISO activity. The references only power up after appropriate commands are received so them being low in a static condition is not indicative of a failure.

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  • The part is powering up correctly from what you indicate, and the parts with Drive=5.6V are awake as well. Is there a pullup on the SDO (assuming normal SPI connection)? If not there will be no MISO activity. The references only power up after appropriate commands are received so them being low in a static condition is not indicative of a failure.

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