When powering an ADR1001 with split heaters, using the LT3045 and LT3094, the LT3094 fails to start, giving 0.6V at its output. The LT3045 starts up normally. Because the LT3094 cannot sink the heater current in its failed state, the ADR1001 never reaches power-good state.
I took the schematic for the ADR1001 straight from the datasheet. The LT3045 and LT3094 circuits were simulated with LTSpice before, but due to a known bug in the ADR1001 model, I cannot simulate the split-supply heater operation.
Measuring with a scope shows that the output of the LT3094 never goes below 0V, instead reaching 0.6V in about 5ms. The PGFB voltage goes to -0.25V.
From other posts, I know that it's best to start up the LT3045 first and then the LT3094; but this is to prevent startup failure on the LT3045, not the LT3094 ( Sequencing startup of bipolar LT3045 and LT3094 ). Is there an obvious mistake in my wiring that I missed?
Thanks!
