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TLV1805-Q1: output voltage and minimum current

Part Number: TLV1805-Q1
Other Parts Discussed in Thread: TLV1805

Dear team,

1. When +IN>-IN, output = V+; when +IN<-IN, output = V-, right?

2. For the minimum reverse current, I don't know why we need to compute this value. Could you please help explain this? For example the minimum reverse current is 640mA based on Rdson(PMOS)=18.75mohm, then what should I do? Which parameter will be impact by this minimum reverse current?

Thanks & Best Regards,

Sherry

  • Hello Sherry,

    #1 - Correct

    #2:

    I assume you are referring to the reverse current app note. If not, this is covered in section 4.1:

     Using Comparators in Reverse Current Applications (Rev. A)

    Maximum offset voltage, hysteresis and Rdson will determine the trip-point. The TLV1805 has 14mV of built-in hysteresis, and ±4.5mV max offset.

    Vtrip = VosMax + (hysteresis/2).

    4.5mV + 7mV = 11.5mV threshold

    Itrip = Vtrip / Rdson

    11.5mV / 18.75mohm = 613mA max

    So the actual current depends on the individual offset/hysteresis of the comparator, and the RDSon of the MOSFET. Since there is no reference voltage or amplifiers to add a more precision threshold, this is a crude circuit that can have variations across devices in operation. The above numbers should be the worst case.

    The MOSFET RDSon ultimately determines the "sensitivity". The higher the RDSon, the lower the reverse current threshold.


  • Hi Paul,

    Got it! This reverse minimum current is the leakage current, right? If we want to achieve smaller leakage current, we need to choose larger Rdson MOSFET, right?

    Thanks & Best Regards,

    Sherry

  • Hi Paul,

    Got it! This reverse minimum current is the leakage current, right? If we want to achieve smaller leakage current, we need to choose larger Rdson MOSFET, right?

    Thanks & Best Regards,

    Sherry

  • Hi Sherry,

    By increasing your Rdson of your MOSFET, you will help lower the minimum reverse current threshold. 

    Does that answer your question?

    Regards,

    Joe