LM3489: High Current Blanking

Mark Siegesmund

Part Number: LM3489

The regulator works well limiting current when I have it set to lower currents (<1A) but at higher settings I get 700us of good regulation followed by 300us of nothing. Attached is a scope trace of the FET gate. Vin is 15V and the output is 13V under load. What am I seeing?

over 8 years ago

0 David Baba over 8 years ago

TI__Mastermind 40060 points

Please check that the current limit is not engaging? DO you have a schematic and a spec you are trying to design to, to share?

Thanks.

0 Mark Siegesmund over 8 years ago in reply to David Baba

Prodigy 70 points

I do expect it to be limiting current however I thought this part did that with quick pulses within the regular duty.

The application is a battery charger that either operates in a constant current (1A-10A) or constant voltage (13.8V to 14.6V) mode. The schematic shows two digital pots to accomplish the control..

Thanks for any advise you can provide.

0 David Baba over 8 years ago in reply to Mark Siegesmund

TI__Mastermind 40060 points

Its really hard to make out the details of the schematic. Can you send a better copy to me at david.baba@ti.com? Thanks.

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LM3489: High Current Blanking