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TL431 reference current Iref

Jaden Ghylin102047
Expert 1140 points
Other Parts Discussed in Thread: TL431

 I am using it to replace a TVS diode. See the circuit below.

 

 

 

I would to know if anyone can tell me what the Iref current would be with the setup I have. We are trying to have the standby current as low as we can (below 8uA). I am not sure if it is feasible to be that low, let me know.

  • 0
    Guru 22270 points

    Hello Jaden,

    What is the reason for selecting the TL431 over a regular TVS?  Have you run into problems using TVS or are you just trying to reduce current draw?

    I believe that these devices have a minimum current for voltage regulation, typically around 0.5 to 1 mA, so don't expect anything less than that.  I can't make out all the resistor values, but if you have 1Mohm with 13.8 V your Iref would be V/R.  The Datasheet for the TL431 gives Iref at 2 to 4 uA so it looks like you have some room to play with.

    You could try putting filters and suppressors on the motors if that is where the spikes are coming from.

    Thanks,

  • 0
    TI__Guru**** 165016 points

    Jaden,

    The main problem is the "off" cathode current. This current increases with Vref greater than 1V.
    The cathode pin is also the "VCC" for the shunt and Vref is also the start up voltage.