How do I measure current in the milliamp (mA) or microamp (uA) range?

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Ted Kuhn

• May 20, 2024 22:00

Hello,

I'm trying to measure current on the 5V rail in the microamp/milliamp range (~1000uA/1mA).  I have a 1kohm resistor connected between RATP00 and RATP16 , but when I run the script to measure the current, I just get 0A, and the test fails.  I've tried with the "disableAutoRange" qualifier, but that doesn't seem to help.  Related question...how do I set the range before specifying "disableAutoRange"?

steps:
  - command: mux 0 RATP00
  - command: mux 1 RATP16
  - command: mux 2 5VOUT
  - command: mux 3 GND
  - command: short 1 3 set
  - command: short 0 2 set
- ident: ICT_T3
  title: Measure
  steps:
  - command: measure currentDMM 5V 900-1500uA
  #  with:
  #   - disableAutoRange

 

Thanks!

0

• Official comment

  

  Ivo Clarysse

  • June 03, 2024 12:11

   

  During `currentDMM` measurements, the MUX subsystem is disconnected from the internal DMM; you can measure the current draw of a 1KOhm resistor directly.

  When autorange is disabled, the range will be inferred from the acceptance range.

  title: "LY11-615: Measure 5mA current draw on 5V rail"
  suite:
   - ident: POWER
     steps:
     - command: power 5V on
     - command: ground 1
     - command: wait
       timeout: 1s
   - ident: MEASURE
     title: Measure
     # 1KOhm resistor between GND1 and 5V.
     steps:
      - command: measure currentDMM 5V 4800-5200uA
  teardown:
    steps:
      - command: power off

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