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LP38691-ADJ: Applying voltage on NC pin

Part Number: LP38691-ADJ
Other Parts Discussed in Thread: LP38691, LP38693

Hi Team,

A quick question here:

Currently looking to use the LP3869x-ADJ as our ldo for one of our products. One thing I noticed is that the LP38691 does not have a enable pin and LP38693 does. We are wanting to use both as interchangeable parts.

Question we had was, can we apply a voltage (the input voltage going to the IC) to the NC pin on the LP38691 where the enable pin would be on the LP38693 without any issues?

Or should we place a jumper before that pin and populate depending if we use the LP38693?



  • Hi Ramon,

    Pin 3 is a no connect, this means that you can hook it up to any voltage as long as it does not exceed the abs max of the part -0.3V 12V, becuase you are tying this to your input, hooking it up will have no problems. We generally recommend hooking up N/C as floating pins or tying them to ground.

    By tying the pin to an active Voltage, you risk damaging the part in the case of a surge, but most likely the IN pin would be damaged at the same time so it should not cause additional problems. You also risk slightly decreased thermal performance, and if this is a concern then you should place a jumper.

    You should not see any problems with the part, However the official position would be to place a jumper and leave the N/C pin floating on the LP38691 as this would be best practice.