LM5020: Cycle-by-cycle over current protection function.

Charlie Xiao

Expert 5390 points

Part Number: LM5020
Other Parts Discussed in Thread: LM5022

Hi Team,

If the voltage at the current sense comparator input exceeds 0.5 V, the MOSFET gate drive is immediately terminated.

When will the MOSFET be turned on again? Thanks.

Regards, Charlie

over 1 year ago

+1 Brigitte over 1 year ago

TI__Guru 60265 points

Hello Charlie,

The switch will be turned on at the next oscillator cycle.

Best regards,
Brigitte

0 Charlie Xiao over 1 year ago in reply to Brigitte

TI__Expert 5390 points

Hi Brigitte,

Thanks for your update.

When the CS point voltage reaches 0.5V and the current protection is activated, will the capacitor in the picture discharge immediately? Thanks.

Regards, Charlie

0 Charlie Xiao over 1 year ago in reply to Brigitte

TI__Expert 5390 points

Hi Brigitte,

If the output terminal is short-circuited, can the current protection of the LM5022 not protect the secondary circuit? Thanks.

Regards, Charlie

+1 Brigitte over 1 year ago in reply to Charlie Xiao

TI__Guru 60265 points

Hello Xiao,

The output power is limited by this, but heavily dependent on the input voltage. What do you mean with protect? The device will not turn of but limit the power.

Best regards,
Brigitte

0 Charlie Xiao over 1 year ago in reply to Brigitte

TI__Expert 5390 points

Hi Brigitte,

Thanks for your update.

When customers are developing, LM5022 is used for non-isolated flyback. When the load is short-circuited, the current on the secondary side of the transformer becomes very large.
But I think that the current protection of LM5022 only limits the power of the circuit, there is no way to ensure the safety of the flyback's post-stage circuit, right? Thanks.

Best Regards,

Charlie Xiao

Power management

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LM5020: Cycle-by-cycle over current protection function.