Part Number:LM5017
I am looking to migrate an existing power supply design to the LM5017 (or any switching regulator with a synchronous rectifier, really) and wondering about the risk of a particular issue. My current design, using a regulator from another vendor, is a USB charger, so a USB battery pack is often connected to the output voltage. I have found that a small number of battery packs have 5V on their input port, either because the input and output ports are connected, or for some other reason. In any case, that acts as an externally supplied voltage that backflows into the regulator and turns it on. When that voltage is at just the right level, the low-side switch starts to operate, which effectively operates as an unregulated boost converter, with the boosted voltage flowing through the body diode of the high-side switch and out of VIN. I have seen this reach as high as 60V.
Anyway, I have used non-synchronous rectifiers in the past and this is not a problem - the external voltage may backflow into the device, but there is no low-side switch and thus no way for the regulator to act like a boost converter. Before I start looking at synchronous buck regulators from Texas Instruments, I want to figure out whether this would be a problem for all synchronous rectifiers, and not just my current regulator. It makes sense to me that any regulator could start to operate in this situation, so I'm curious if there is some way the the LM5017, or any other regulator with synchronous rectification, would fare better.