TPS61062 PWM dimming application

Jerel Xu

Other Parts Discussed in Thread: TPS61062, TPS61160, TPS61161, TPS61061

Customer wants to use TPS61062 EN pin for PWM dimming,datasheet indicates PWM should be less than 1kHz?I want to know why?I think,if I pull EN pin high at leat 1ms for the first time start up,we can improve PWM frquency 5KHz or 10KHz?According to TPS61062 block diagram,when TPS61062 starts up,EN pin is to shut off TPS61062 output by OVP circuit,I think 5K or 10K is ok for OVP circuit.

over 14 years ago

0 Jeff F over 14 years ago

TI__Guru**** 166576 points

The main concern is not the OVP circuit but is the start up time for the converter. As shown in figures 8 and 11, the LED takes almost 400us to settle to the maximum value. Therefore at faster switching frequencies, the average current will be lower than expected.

0 Jerel Xu over 14 years ago in reply to Jeff F

TI__Prodigy 180 points

If I pull EN pin to high 1ms for TPS61062 first start up,TPS61062 can finish start up,then can we increase PWM frequency to 10K or high?

0 Jeff F over 14 years ago in reply to Jerel Xu

TI__Guru**** 166576 points

I don't think so. Have you looked at the TPS61160 or TPS61161?

0 Jerel Xu over 14 years ago in reply to Jeff F

TI__Prodigy 180 points

In fact,I did one test:After TPS61062 starts up,we send 5K PWM to EN pin,duty cycle is 10%,I tested SW pin waveform and found TPS61062 turned on and off normally,can you try in TPS61062 EVM?

0 Jeff F over 14 years ago in reply to Jerel Xu

TI__Guru**** 166576 points

We did not test the TPS61061 for this type of operation and so we cannot guarantee it will operate as expected.

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TPS61062 PWM dimming application