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LM66100: Forward current still present when CE is pulled high

Stephen Monn1
Prodigy 20 points
Part Number: LM66100

Perhaps I am missing something, but I believe this device is supposed to behave a disabled p-channel mosfet when CE is pulled higher that Vout. However, in testing this, I still see a forward current when these conditions are met, which is not how a p-channel mosfet would behave.

Wiring:

Vin = 3.3v

CE = 5v

ST = GND

Vout = connected to a 3kOhm load to GND

Measuring the voltage drop across the load gives me 2.8V meaning there is still a large forward current flowing. I have repeated this test on multiple lm66100s and the results are consistent. Is this the expected behavior of the chip? Does it really only protect from reverse current when in the OFF state?

  • 0
    TI__Mastermind 32650 points

    Hi Stephen,

    The body diode for the pFET in LM66100 is positioned from input to output. Refer to Section 8.2 in the datasheet for the block diagram of this device.

    The voltage on the output seems to line up with the input voltage minus the diode drop.

    In your application, why did you choose to use the LM66100 over a load switch?

  • 0 in reply to Shreyas Dmello
    Prodigy 20 points

    Thank you! I totally overlooked the body diode... I was just trying to get a good understanding of the chip, but I ultimately plan on using it in the suggested "Always-ON Reverse Current Blocking" mode.

    I didn't want to use a load switch due to their higher cost. My application is more controlled and I can get away with using just one diode, plus I liked the status feature of the LM66100.