Can I pull RUN pin low and have a voltage applied externally to the output of LTM8078 without damage?

Question

Accepted Answer

Yes, you can safely pull the RUN pin low to place the device into micropower shutdown mode. In this state: 
 1. The internal circuitry is mostly powered down. 2. The output is not actively driven, meaning the output power switches are turned off. 3. However, the output is not actively pulled to ground, so it becomes high impedance. 
 This means that applying an external voltage to the output while RUN is low will not damage the device, as long as: 
 1. The external voltage does not exceed the absolute maximum rating for the output pins (which is 10V for VOUT1 and VOUT2). 2. The current sourced or sunk into the output pins is within safe limits (i.e., avoid forcing large currents into the output). 3. This behavior is useful in applications where you want to override the LTM8078’s output with another power source or share a rail between multiple regulators. 
 Do note that the external voltage in the output might leak to the input (VIN) of the controller due to the body diode of the internal Mosfets.

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LTM8078: FAQ