Noob question - The chip enable pin of a SRAM is drawing 1.2A

Discussion in 'Digital Circuit Design' started by Angel RF, Jul 14, 2019 at 7:08 AM.

  1. Angel RF

    Thread Starter New Member

    Sunday
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    I have a AM9101 Static RAM chip, and I want to use it with Arduino.
    My setup is in a breadboard, and I'm only connecting VCC and GND, but when I connect CE (Chip enable, active low) to ground, the current from CE pin and ground is 1.2A.
    I figurate that this is not normal, but it does the same with a second AM9101 chip.
    Am I doing something badly? Maybe I can't connect CE directly to ground, but with other chips I can do it directly.
    Please help, thanks for your time.
     
  2. KeithWalker

    Member

    Jul 10, 2017
    266
    83
    You either have the chip connected wrongly or your measuring instrument is faulty. Can you show a diagram of how you have it connected? What are you using to measure the current?
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Welcome to AAC!
    If you have input pins floating that can generally have weird effects, including excessive current draw. I don't know if that applies to your particular IC though.
    I would expect 1.2A through the CE input to have caused IC damage.
     
  4. BobTPH

    Senior Member

    Jun 5, 2013
    1,735
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    If the chip was not smoking, it is doubtful that it is drawing 1.2A.

    Are you sure there is not a little m in front of A?

    And do show us how you measured, i.e. how you placed the probes of your multimeter.

    Bob
     
  5. Angel RF

    Thread Starter New Member

    Sunday
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    Thanks for the replies,
    I made a little diagram "diag.png" in paint.

    I'm sure that the meter shows "A" in current mode

    I'm sure too, that I connected it properly.

    Maybe, but before, I had it with almost all pins in a determined logic level with arduino, and the same result.

    A other thing, there are two CE pins, one active low, and the oher active high, but all of them draws 1.2A. (One to GND and the other to VCC).

    Thanks for your help, any idea?
     
  6. jpanhalt

    Expert

    Jan 18, 2008
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    When I search on the old AM9101, this is the pinout that I find:

    upload_2019-7-14_17-50-19.png

    Please show the "real" pins that you are using and a link to its datasheet. It's like we know you think it is connected properly, but that current you are getting is way wrong.
     
  7. Angel RF

    Thread Starter New Member

    Sunday
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    Ok, here I attached some pictures, and the datasheet that i'm using:
    20190715_114051.jpg 20190715_114154.jpg
    As you can see, I have +5V in the pin 22, VCC in the datasheet, GND in pin 8, VSS in datasheet, and GND thru the meter in pin 19, CE1 (active low) in datasheet.
     
  8. jpanhalt

    Expert

    Jan 18, 2008
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    Presumably, the alligator clips are your power supply. Show how your meter is attached. If those clips are your meter, where is your power supply? Moreover, they are not connected correctly to measure current through the chip.
     
  9. KeithWalker

    Member

    Jul 10, 2017
    266
    83
    From what I can see in your picture, you have your ammeter connected between + and - of your 5 volt supply, shorting it out. What your meter is displaying is the limiting current of your power supply.
    Try connecting it as you show in your diagram. You will measure a much smaller current.
     
  10. WBahn

    Moderator

    Mar 31, 2012
    24,237
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    As has been stated previously (and clearly ignored) do NOT leave inputs unconnected (unless the data sheet specifically states that this is acceptable).

    You are NOT measuring the current through the chip enable pin, you appear to be shorting out your power supply and reading its short-circuit output current.
     
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