Current Control

Discussion in 'General Electronics Chat' started by Vindhyachal Takniki, Sep 2, 2016.

  1. Vindhyachal Takniki

    Thread Starter Member

    Nov 3, 2014
    349
    6
    1. I have to control current of a load, so that whenever load increases from 5A it should trip & second there is no reverse current.
    Operating voltage is 9V to 12.6V.

    2. I was looking at LTC4358, it says its ideal diode for 5A. Features in it says "0.5μs Turn-Off Time Limits Peak Fault Current".
    Does that mean it will trip after peak current? What's its value in datasheet? Also will the system auto retry after fault condition?

    3. Also diode minimum operating voltage is 9V, what if any case error system voltage falls below it? Will the diode shut off or LTC4358 may overheat as its internal mosfet cannot be turn on completely?
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,153
    3,059
    Like a real diode, that device won't shut down when/if the load current exceeds 5A. The turn-off time is referring to a condition where the polarity has reversed, and it is switching to prevent reverse current. (A MOSFET can conduct in either direction, so it must be turned off to prevent reverse current.)

    You need something like a circuit breaker, or a resettable fuse, or a current-limned power supply. It depends on just what you need to do.
     
  3. hp1729

    Well-Known Member

    Nov 23, 2015
    1,964
    219
    Wow, a self-synchronizing synchronous rectifier?
    Re: "... Will the diode shut off?"
    Yes, that's the way I read it. It just won't turn on below 9 V. The internal diode may still work but it is only rated at about 1 Amp. It's main purpose seems to only be to get VDD going to get the "synchronous rectifier" started.
    #12 has some good stuff here in the forums on synchronous rectifiers.
     
    Last edited: Sep 2, 2016
  4. wayneh

    Expert

    Sep 9, 2010
    12,153
    3,059
    You're probably referring to the 9V issue, but the TS needs to understand this device will not limit current to 5A. It's a diode, not a circuit breaker.
     
  5. Vindhyachal Takniki

    Thread Starter Member

    Nov 3, 2014
    349
    6
    How about using TPS25944A.
    It gives current limit & provide reverse current protection also.
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,153
    3,059
    It seems like a fancy chip. If it meets your needs, go for it.

    Others may recommend simpler (and cheaper?) options if you can better describe your needs. For instance a diode and a circuit breaker would also seem to solve your needs. But perhaps you need more than that.
     
  7. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,147
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