LM5069: GATE drop issue

Tommy Tzeng

Part Number: LM5069

Hi Team,

i have question.

1.There are two input voltages, one is ac adapter 24V, the other is battery pack (12V~16.8V 4S1P).

2.When the AC adapter is removed, the battery is continuously powered, and then the Ac adapter 24V is reinserted. At this time, the pin#10 of the LM5069 will fall between 14V ~15V,

and the voltage of the Battery pack is 14V~15V. Not only lm5069 pin#10 gate voltage drops, and Power Good will also drop this.

So lm5069 can't be designed like this? Dual power input. Because the transient will from 14v~15v (battery voltage) to 24v (adapter power).

attachment is my schematic and input function block.

RITY-153- A1.pdf

over 5 years ago

0 Rakesh over 5 years ago

TI__Guru** 105361 points

Hi Tommy,

In the above block diagram, you are referring to back-to-back MOSFETs but I did not see them in the schematic. Is it the full schematic ?

Can you share test waveform when Ac adapter 24V is reinserted. Please include Ac adapter voltage, battery voltage, GATE voltage of LM5069 and current through the hot-swap FET.

BR, Rakesh

0 Tommy Tzeng over 5 years ago in reply to Rakesh

Genius 5780 points

Hi Rakesh,

very sorry~i'm wrong. customer use diode as adapter to isolate battery, please kindly refer the schematic for the main.

c1:GATE pin waveform

c2 timer pin waveform

0 Rakesh over 5 years ago in reply to Tommy Tzeng

TI__Guru** 105361 points

Hi Tommy,

Seems LM5069 is triggering OC event when AC adapter 24V is reinserted.

Can you also include AC adapter voltage and current through the LM5069 path in the above test waveform to check.

BR, Rakesh

0 Rakesh over 5 years ago in reply to Rakesh

TI__Guru** 105361 points

Hi Tommy,

Any updates ?

BR, Rakesh

0 Rakesh over 5 years ago in reply to Rakesh

TI__Guru** 105361 points

Hi Tommy,

I am closing this thread. Feel free to reopen as soon as you get updates..

Thanks, Rakesh

0 Tommy Tzeng over 5 years ago in reply to Rakesh

Genius 5780 points

Hi Sir,

got it, because the customer not yet responded to us, i'll push again.

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LM5069: GATE drop issue