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CD4541B: Total quiescent current

KEVIN BARRETT
Prodigy 40 points
Part Number: CD4541B
Other Parts Discussed in Thread: CD4047B, CD4011B

The quiescent current is rated at 10uA max for 10V.

It is not clear to me if that rating is with the oscillator running or not.

I ask because my timer circuit is drawing 270uA while running and I want to be sure this is normal.

There is a note in the CD4541B data sheet referring to quiescent current.

it reads as follows:

 With AUTO RESET enabled, additional current drain is
30μA (Typ), 350μA (Max) at 10V;

Does this note mean that with auto reset disabled, the quiescent current is 350 - 30 or 320uA typical?

Thanks..

  • 0
    TI__Mastermind 42660 points

    Hi Kevin,

    This note indicates that at 25 C, 10 V, and with AUTO RESET enabled the maximum Icc is 350 uA.

    I don't think this is abnormal if the device is in operation.

  • 0 in reply to Dylan Hubbard
    Prodigy 40 points

    Right, but I am running it with auto reset disabled. so what should the max current be in that case?

     With AUTO RESET enabled, additional current drain is
    30μA (Typ), 350μA (Max) at 10V;

    I am keying in on that word "additional."

  • 0 in reply to KEVIN BARRETT
    Prodigy 40 points

    Having worked at RCA where these parts originated, I found  graph in the application note for the CD4047B which sheds light on this whole thing. The quiescent current in the data sheet is with the part in the reset mode, so that number is low. the rating with the auto rest enabled is and increase in the quiescent current. Neither of those numbers reflect the current when the oscillator is on. For that we need to look elsewhere. And it is in the old RCA data books where you can find it.

    here we can see that a simple oscillator made from say a CD4011B would draw about 500uA at 10V. The 4047B would draw about 30uA. and my 4541 is somewhere in between that at 270uA. I did confirm that dropping to 5V halved the current to 180uA. Last thing to try is a small capacitor with larger resistors. I hope this information helps others. My application here is trying to minimize total operating current for longest battery life