LM34927: Current limit spec of LM34927

Ella KIM

Part Number: LM34927

Hi,

I wonder the current limit spec of LM34927. Datasheet specifies its threshold is 1.02Vtyp.

But it looks this threshold is for a peak value, but average value would be less than the peak value according to DS below. Does this mean current limit can be triggered even with the current in the buck switch < 1.02A?

What's endurable current spec not to damage the device? Customer reported LM34927 was damaged in the EVM while supplying power to gate drivers on their board. They are looking for reason and putting a possibility that the load current was too high, so they want to check the endurable current spec of LM34927.

Thanks,

over 2 years ago

+1 Andy Chen over 2 years ago

TI__Mastermind 27045 points

Hi Ella,

The LM34927EVM only can drive 150mA load for +V or -V output.

Pls use power supply to drive the load board to check out the actual load current first.

B R

Andy

0 Ella KIM over 2 years ago in reply to Andy Chen

TI__Expert 3862 points

Andy,

Thank you for your advice.

Andy Chen said:
The LM34927EVM only can drive 150mA load for +V or -V output.

Could you clarify 'for +V or -V output'? What does '-V' (negative voltage) mean?

I have one more question.

As per EVM guide, LM34927 can basically operate more current than 300mA if the coupled inductor is properly sized. I'm confused with 'a sustained current situation'. Is it saying that LM34927 can be designed with load current upto 1.02Atyp (current limit threshold), or 600mA (switching HS FET current rating as per datasheet p1)?

+1 Andy Chen over 2 years ago in reply to Ella KIM

TI__Mastermind 27045 points

Hi Ella,

Sorry, it should be Vout1 and Vout2.

If secondary Vout2 is light load <50mA, then the circuit works more like buck converter and the primary Vout1 can output about 600mA if the inductor can handle peak current up to 1.02A at Vin-max

B R

Andy

0 Ella KIM over 2 years ago in reply to Andy Chen

TI__Expert 3862 points

Thank you Andy for the clarification!

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LM34927: Current limit spec of LM34927