LMR62421: Vin Supply External 3V voltage

Neal Zhu

Expert 2470 points

Part Number: LMR62421
Other Parts Discussed in Thread: LMR62014

Because it's a boost to the battery,battery is 0.9-1.6V, Vout 18v, But datasheet Vin min is 2.7V,

so,Vin external 3 V,inductance is connected to the battery,Separate the power supply,Is that ok?

Thanks!

over 4 years ago

0 Zack Liu over 4 years ago

TI__Mastermind 34201 points

Hi Neal,

What's the load current? If it is working at CCM, you have to consider the maximum duty cycle limit and current limit.

0 Neal Zhu over 4 years ago in reply to Zack Liu

Expert 2470 points

Hi,

DCDC outputs about 17V,Drive LED by controlling LED negative conduction with pulse type (e.g., 20uS every 20mS interval),

In 20uS the current is around 100mA and it could be up to 1A,the rest of the time no conduction no current.

Thanks~

0 Zack Liu over 4 years ago in reply to Neal Zhu

TI__Mastermind 34201 points

Hi Neal,

Is below load current waveform correct?

What do you mean it could be up to 1A?

0 Neal Zhu over 4 years ago in reply to Zack Liu

Expert 2470 points

Hi Zack,

yes,20us up to 100mA,or up to 1A(possibility).

Thanks!

0 Zack Liu over 4 years ago in reply to Neal Zhu

TI__Mastermind 34201 points

Hi Neal,

100mA is ok with 10uF output capacitance. But 1A is too big for 10uF output capacitance. You have to use a bigger capacitor at output to deal with big load current transient.

You can use attached TINA model for simulation. Here I used LMR62014, you can replace it with LMR62421.

7367.LMR6201418Vout.tsc

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LMR62421: Vin Supply External 3V voltage