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Unconnected pin 3 on EP5388QI, problem or not?


In an older application, we would like to change the EP5368QI for an EP5388QI since we're running into over-current problems at ambient temperatures at the lower end of the temperature range (-40°C). This is for an 4.3 V -> 1.8 V supply (VID setting). The supplies do start-up at this temperature, but when the load increases after startup to something in the order of 500 mA, over-current seems to trip and the supply restarts.


The problem here is that in the EP5368QI pin 3 is n/c while in the EP5388QI pin 3 is GND. We checked on a couple of devices and indeed, there is no connection between pin 2 (GND) and pin 3 (n/c) for the EP5368QI, but for the EP5388QI both are GND (and seem to have a very low-ohmic connection between them).


If we just swap out the EP5368QI for the EP5388QI, it means one of its GND connections will be left floating. This is not an ideal situation, but given the fact that we can't retrospectively change the PCB, how bad would this be? We can accept degraded ripple-specs, but is there something else which we should be concerned about?

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1 Reply

Hello Arjen,


I really apologize for the delay that happened to this case where the case just escalated to me.


Regarding Pin 2, 3 for both EP5368 and EP5388 are PGND and connecting both of the pins to GND will help to increase the efficiency.


There is no issue if you didn't connect one of them on the device functionality.


I had sent a personal email to you before regarding the startup issue, please feel free to contact me if you still have an issue there.

I will check internally how we can speed the escalation process.



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