LM358: Output current

James Zhan

Expert 4365 points

Part Number: LM358

Hi team,

Could you please help to explain of the output current meaning as below table shows?

When Vs=15V, Vo=0V, VID=1V, source current -30mA(typ) and Vs=15V, Vo=15V, VID=-1V, sink current 12mA(min)?

Thanks.

James.

over 7 years ago

0 kai klaas69 over 7 years ago

Guru 140200 points

Hi James,

have a look at figures 8, 9 and 10 of datasheet. This should make things clearer.

Kai

0 Paul Goedeke over 7 years ago in reply to kai klaas69

TI__Mastermind 30600 points

Hi James,

Which part of this specification is confusing to you? The LM358 output stage has different source and sinking capabilities, which is why the numbers are different. If a circuit configuration is such that current goes into the op-amp output (load tied to VCC and output voltage less than VCC) then it is sinking current. Sourcing current is a more typical scenario, with output voltage higher than the load termination voltage.

Hope that helps,
Paul

0 James Zhan over 7 years ago in reply to Paul Goedeke

TI__Expert 4365 points

Hi Paul,

Thanks for the explanation.

Could you help to figure out this? I have 10kohm load, and I have Voutput=15V at the start up time, and then Vout drop to about 5V. Could LM358 due with the startup current spike?

James.

0 Paul Goedeke over 7 years ago in reply to James Zhan

TI__Mastermind 30600 points

Hi James,

I don't understand the question. Are you saying that when you apply power to the amplifier, the output spikes to 15V and then drops to 5V? Can you attach a screenshot and schematic?

-Paul

0 James Zhan over 7 years ago in reply to Paul Goedeke

TI__Expert 4365 points

Hi Paul,

This is a question from customer, and I didn't have the waveform yet.

15V to 5V is just the response of input voltage changes, not meaning the supply voltage. I believe the supply votlage stays flat.

Thanks.

James

0 Paul Goedeke over 7 years ago in reply to James Zhan

TI__Mastermind 30600 points

Okay. If you have any more information in the future, let me know and we can work on that question.

Thanks,
Paul

0 James Zhan over 7 years ago in reply to Paul Goedeke

TI__Expert 4365 points

Hi Paul,

This LM358 use for 220V line current sensing, they use a 10kohm resistor as amplifier' load, and the output voltage is 0~5V. Could LM358 output current satisfy this resistor?

By the way, customer feedback the current will have a spike in start up,and they didn't have the waveform yet.

Thanks.

James

0 Ron Michallick over 7 years ago in reply to James Zhan

TI__Guru**** 170776 points

James,

For a 10k resistive load to ground and op amp output 0V to 5V is fine. Load current will be 0uA to 500uA; from op amp through resistor to ground.

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LM358: Output current