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TPS22919: What is leakage current through VOUT when VIN is Off

Jayjit Yadav
Prodigy 160 points
Part Number: TPS22919
Other Parts Discussed in Thread: TPS61240, , TPS22916, TPS22917

Hello,

we are working on the 2F 5V super capacitor charger we have used TPS61240 for Boost converter from 3.3v to 5V and after that we have placed Resistor to control the current to Charge the supercapacitor. but we need to avoid the Reverse and Leakage current from Capacitor to VIN, when we are turning off the supply once the Supercapacitor fully charged. we are thinking to use the TPS22919 device as its leakage current is very less 2nA.

1) so my question is can we use this load switch IC for our Application??

2) if we Removed (Off) the VIN Supply to turn off the Load switch (TPS22919) what is the Leakage and Reverse current through VOUT Pin ? is there any voltage  present  at VIN due to internal MOSFET body diode ? 

3) we have to avoid the Discharging of Supercapacitor with Leakage and Reverse current through VOUT please also suggest if any other option available.

4) Have look on below block diagram for more clarification.

  • 0
    TI__Mastermind 32650 points

    Hi Jayjit,

    TPS22919 has no form of reverse current blocking. I think for your application, this device will not work.

    Have you looked at TPS22916? 

  • 0 in reply to Shreyas Dmello
    Prodigy 160 points

    Hello Shreyas

    Thanks for the Information, but in TPS22916 body diode will conduct from OUT to IN when there is No input which cause reverse current to flow right ?

    because there is Reverse Blocking section in the Block diagram ahead of mosfet from out to in. which is not clear to us what it consist ?

    in the Datasheet Shutdown current is the Reverse current Right ?

    in Shutdown current Specification all the Current values given according to the VOUT=GND but in our case capacitor is at output so there will be the 5V at out put when no input what will be the Shutdown current in that case ?

    and what is the Shutdown current for TPS22916CN as there is no built in Resistor across QOD Section ?

    also could you please suggest the similar Device according to our application with 105 °C operating Temp ?

  • 0 in reply to Jayjit Yadav
    TI__Mastermind 32650 points

    Hi Jayjit,

    TPS22916 has always ON RCB. This means that as long as the reverse current threshold is hit (Ircb), the device will block reverse current. 

    Shutdown current is NOT reverse current. Shutdown current is the current that flows into the device when the device is disabled and Vout is held at GND.

    Reverse current is the current that is flowing from OUT to IN.

    The Reverse Current Blocking block in the diagram is internal circuitry implemented to allow for always ON reverse current blocking.

    TPS22917 is a similar device that can do 105C operating temperature.