TPS61160A: Selection of Current Limiting Resistor

Steve Glowacki

Part Number: TPS61160A

I'm designing an LED backlight circuit needing 19.2v with 18-20ma using the TPS61160A. Plan is to use 5v input voltage, 1uf Caps on input and output, 22uH Inductor, .22uf Comp Cap, with PWM dimming (approx 20-100%).

My question is to verify both the resistance VALUE and POWER ratings. Which Vfb ref do I us: Vref or Vref-pwm to calculate this? Also, how do I calculate the power rating for this resistor?

Apologies if this is a basic question, but would appreciate the assistance.

Thanks,

over 4 years ago

0 Sean Zhou over 4 years ago

TI__Mastermind 22745 points

Hi Steven,

First, the cap connected to "COMP" pin should be about 220nF, not 22uF.

The VFB reference value is 200mV, for example, if you want to get 20mA, so RFB=200mV/20mA=10ohm;

For power rating, you need refer to datasheets for the similar efficiency test curve and estimate the power loss, Since this is a system level question.

Regards

Sean

0 Steve Glowacki over 4 years ago in reply to Sean Zhou

Prodigy 40 points

Thanks for the verification.

0 Sean Zhou over 4 years ago in reply to Steve Glowacki

TI__Mastermind 22745 points

Hi Sir,

Sure, any question, please let us know.

Regards

Sean

Power management

Power management forum

TPS61160A: Selection of Current Limiting Resistor