I have a project with the LM66200 which is correctly switching between Vin1 and Vin2 as per which has higher voltage level. The issue I am facing is when both Vin are removed, and Vout persists high (due to bus capacitance for instance) I see that the LM66200 reverse conducts to the last Vin that was active. In other words, once both Vin power sources are removed, I observe the device latching to the latest higher Vin and allowing reverse current back into this specific Vin.
A few notes:
- I have seen reverse currents as high as 200mA when in this latch-up situation, so I think this is not just junction leakage
- Voltage operation in my application: 4.5 to 5.2V
- Vin1 has a nominal 5V power supply line and resistive loads in that line
- Vin2 has a nominal 5V power supply line and resistive loads in that line
- When both Vin1+2 power are removed, I observe the loads on the given Vinx that was last seen higher, being fed by current coming from Vout
Does the device need to have at least one of the two Vinx >1.6V at all times to prevent reverse current (and latch-up)?
