Negative Current

Issues
1

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Hi sir iam getting the negative current while doing BLE device current measurent in sleep condition, can you please help what could be the issue,

2

Hi @NGS - According to what you sent, the current range is -8.4 to -2.4 µA, which is compatible with the JS220’s ±18 µA range. The JS220 has different offset accuracy in each range:

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Can you confirm that your test setup allows the JS220 to reach the ±18 µA range? Add the r signal (current range) in the Device Control widget and in the Waveform shown in orange like this:

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Also make sure the items in green are set as shown.

Some questions:

  1. Can you confirm that you are using a JS220, not a JS110?
  2. Can you confirm that the JS220 reaches the ±18 µA range?
  3. Can you share an image or a brief JLS file that includes the current range signal?
  4. Can you confirm that you have no other connections to the target, including debuggers and UART adapters? These connections can provide power and alternate current paths that matter when you care about < 1 mA.
3

hi sir,
1 Ans : Iam using JS220 joulescope only
2 Ans : i have set the range to 18uA to 18 mA.
3. yes pls find below.
4. yes no other devices connected,only joulscope connected to PC.

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4

Hi sir, i did settings as per you guidance, iam still getting current in negative scale, unable to understand sir, please help.

5

Hi @NGS - If you disconnect the voltage and current terminals on your JS220, what do you measure? The offset spec is ± 30 nA.

If you do not measure this, please try restoring the factory calibration:

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Does this help?

6

Hi sir,
when i disconnected all terminals of joulscope, i see it is reading -5 to -9 uAmps.
so i did as per your suggestion as below, please see.
i did the current offset and voltge offset ,
after that , i just started the waveform & i see this idel current profile as below.

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is it okay ??
please confirm sir.

7

Hi @NGS - I do not understand what you did.

It sounds like you may have pressed Start for both Current offset and Voltage offset.

I recommended pressing Restore factory calibration. Is this what you did that resulted in the correct offset values?