LM3405A: maximum duty cycle

Takao Yamamoto5

Expert 1690 points

Part Number: LM3405A

Hi team,

Could you teach maximum duty cycle over all temperature and input voltage?

I think that the condition of 85% spec. at data sheet is all temperature range, but Vin = 12V.

I checked how LM3405A work when FB=0V at room temp. and the result is blow.

Vin 14V -> 86.9%

Vin 12V -> 84.8%

Vin 10V -> 82.0%

Your answer will be helpful because I am considering the detection voltage range in order to detect failure when output is open.

Best regards,

over 3 years ago

0 Frank Qiu over 3 years ago

TI__Genius 15776 points

10.1 -10.7 is Chinese notional holiday, our expert will reply you after 10.8. if it's an urgent case, please directly communicate with the person who is assigned.

0 Takao Yamamoto5 over 3 years ago in reply to Frank Qiu

Expert 1690 points

Do you have any update? It is helpful that your information.

Yamamoto

0 Yuting Shao over 3 years ago in reply to Takao Yamamoto5

TI__Genius 13001 points

hi,

I can't understand the relationship between VIN voltage with open failure. Could you explain more about the logic?

Robin

0 Takao Yamamoto5 over 3 years ago in reply to Yuting Shao

Expert 1690 points

Hello,

Sorry for confusing you. I would like to send question again.

Simple question, I would like to know what maximum Duty will be when FB=0V at Vin = 10~14V range.

My system Vin = 10~14V. On the other hand, I think that the condition of datasheet is 12V only. Therefore, I want to check above.

Best regards,

Yamamoto

0 Takao Yamamoto5 over 3 years ago in reply to Yuting Shao

Expert 1690 points

Hi Mr. Shao,

If it takes a lot time to check Duty in detail, could you answer following for 'yes' or 'no' at first?

It is helpful to answer this ASAP.

> QUESTION,

Condition: Vin = 10.8V, FB = 0V

Will the minimum value of D_max be 80% or more?

Best regards,

Yamamoto

0 Yuting Shao over 3 years ago in reply to Takao Yamamoto5

TI__Genius 13001 points

hi,

i can't give you the accurate data since it can only be obtained after a large number of experiments. according to my limited experimental data, >80% is achievable.

robin

Power management

Power management forum

LM3405A: maximum duty cycle