Timeline for Sensing current down to tens of nA with INA828 or other OPA
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Nov 19 at 18:48 | comment | added | spanito | Thanks for your suggestion! | |
| Nov 19 at 7:14 | comment | added | jpa | @BenVoigt Enough for opamp output to go to Vref + R1 * Iload (or Vref + V_D2 if the diode is used). Depends on opamp how much supply margin it needs to give the required output voltage at the load current. | |
| Nov 18 at 19:52 | comment | added | Ben Voigt | What kind of supply voltage do you think you need for OA1, in order to keep the inverting input at 3.3V when the device is drawing "high current" in between sleep cycles? | |
| Nov 18 at 14:14 | history | edited | jpa | CC BY-SA 4.0 |
Note about D2 leakage (thanks Neil_UK!)
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| Nov 18 at 14:01 | comment | added | Neil_UK | Don't use a low voltage zener for D2 (anything <5 V), they have very high leakage at surprisignly low voltages and may cause error shunting R1. Use instead a diode-connected transistor, or even an LED, far better than a low voltage zener. OR, left-field idea here, omit R1 and use a silicon diode for D2 if you want a log-scale reading, albeit with low accuracy, though it's easy to compensate for the D2 tempco with a similar one in the other opamp leg. | |
| Nov 18 at 7:43 | history | answered | jpa | CC BY-SA 4.0 |