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LM66100: Problem behavior ideal diode LM66100

Fabien Dumont
Prodigy 10 points
Part Number: LM66100

Hello,

I am posting this topic regarding the use of the LM66100 component. I am working on an externally powered device. I want to measure the voltage under charge of the battery.


The goal is to activate transistor Q7 for a very short time (approx. 1ms) and to measure 3V6 under load (R44 and R48). We observe that the capacities on VDD disrupt this measurement (in particular C2). We do not use a diode, due to overconsumption and voltage drop. We want to use an ideal diode (LM6610) in order to limit consumption and voltage drop. I used the Always-ON Reverse Current Blocking (RCB) setup, however I am not seeing the correct behavior.

Behavior with a diode. Blue = VDD Yellow = 3V6 The representation corrects the offset linked to the diode.

Comportement avec le LM66100
Bleu = VDD
Jaune = 3V6

Is this component suitable for this use case?

Thanks,

Fabien

  • 0
    TI__Mastermind 28640 points

    Hi Fabien,

    Welcome to e2e!

    In order for RCB (reverse current blocking) to activate when CE is connected to VOUT, CE needs to be 35mV (typ) higher than VIN. Since R44/R48 do not create a strong pulldown to GND, relatively little current flows from VOUT to VIN and creates a voltage drop <35mV, which is why CE does not go high enough to disable the device and there is not enough reverse current to trigger RCB.

    What voltage is VBAT_OUT's high level? If it's high enough (and that situation is all you will need TPS66100 off for), you can connect CE to VBAT_OUT and it will disable the device when this measurement is being taken.

    Thanks,

    Patrick

  • 0 in reply to Patrick Shalton
    Prodigy 10 points

    Hi Patrick,

    Thanks a lot for your quick response,

    I think the component is difficult to implement for my application.

    Best regards,

    Fabien