TPS61161: Use TPS61161 as a camera flash driver to drive 10 LEDs in series at 30V/80mA

John Yang3

Prodigy 80 points

Part Number: TPS61161
Other Parts Discussed in Thread: TPS61169,

Hi Sir,
If we design as below. Can we use TPS61161ADR?

Input voltage range = 3.2V-4.2V, Li-ion battery supplied voltage

Output voltage range = 30V, 10 series LED, with 3.0V nominal voltage each

Output current = 80mA.

Rset = 2.49ohm 1%

Regards,
John

over 5 years ago

0 Sean Zhou over 5 years ago

TI__Mastermind 22745 points

Hi John,

We suggest to use TPS61169, since TPS61169 has a higher current limit.

Regards

Sean

0 John Yang3 over 5 years ago in reply to Sean Zhou

Prodigy 80 points

Hi Sean,

Because our design is on going. If use TPS61161 at 30V/80mA is workable or not?

Should we must change to TPS61169?

Thanks,

John

0 Sean Zhou over 5 years ago in reply to John Yang3

TI__Mastermind 22745 points

Hi John,

Yes, for your specification, it only can support about 40mA, so you need to change to TPS61169 with higher current limit.

Regards

Sean

0 John Yang3 over 5 years ago in reply to Sean Zhou

Prodigy 80 points

Hi Sean,
I have some question about this component TPS61169.

1.What is the maximum output current this TPS61169 support?

2.If we want use 30v/80mA. The Rset/Cout/Cin do you have suggest value or any reference design?

3.The Schottky Diode is recommend NSR0240 is this fit for all design?

4.Inductor LPS4018-472ML 4.7uH is this fit for all design?

Thanks,
John

0 Sean Zhou over 5 years ago in reply to John Yang3

TI__Mastermind 22745 points

Hi John,

The outpt current is a system level question, not only limited by current limit, but also vin, vout and inductor value. Here are some AN that may be helpful for you:

http://www.ti.com/lit/an/slvaeg0/slvaeg0.pdf

http://www.ti.com/lit/an/snva763/snva763.pdf

Regards

SEan

0 John Yang3 over 5 years ago in reply to Sean Zhou

Prodigy 80 points

Hi Sean,

If need 30V/80mA, Rset my calculation is 2.49ohm. is it correct?

Thanks,

John

0 John Yang3 over 5 years ago in reply to Sean Zhou

Prodigy 80 points

Hi Sean,
I recalculate TPS61169 30V/80mA the Rset should be 2.55ohm. Is it correct?

By the way, you said TPS61161 only can support about 40mA.
I didn`t found that at TPS61161 datasheet. Could you tell me where I can find that information?

Thanks,
John

0 Sean Zhou over 5 years ago in reply to John Yang3

TI__Mastermind 22745 points

Hi John,

Yes, for 80mA, Rset is about 2.55ohm.

have you read the application note I send as the above reply. The output current should be calculated based on the application specification. Please refer to above application note to calculate the current.

Regards

Sean

0 John Yang3 over 5 years ago in reply to Sean Zhou

Prodigy 80 points

Hi Sean,

Yes I read that. But I can`t calculate 40mA this value.
Could you tell me how to calculate this value?

Could you please also give me 2.55ohm mathematical formula that you used.
I want make sure not use the wrong mathematical formula.
Because we may change the output current in the future.

Thanks,
John