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TPS61163A: PWM Dimming Ratio

hideyuki sakai
Mastermind 6250 points
Part Number: TPS61163A

Dear, Sir.

My customer is considering to apply TPS61163A as bach-light driver for Smart Phone.

They don't want to use "EasyScale interface" because their system only has PWM signal.

The other side, they are expecting the dimming ratio over 511 steps.

So that I would like to confirm the bottle-neck of PWM dimming ratio.

I hope your advice and help at this time.

1. 100:1 PWM Dimming ratio.

    I think the ratio will be depended on the clock speed of "Duty decoding" block.

    Also thinking the clock source will be "OSC".

    I wonder my asumption is correct?

2. Method to elevate PWM Dimming ratio.

   The datasheet is recommended "PWM dimming signal frequency" from 10kHz

   to 100kHz.

   Is it possible to expand the lower frequency than 10kHz, such as 5kHz or 1kHz?

Best Regards,

H. Sakai

  • 0
    TI__Expert 4550 points
    Hi Sakai,
    For your question:
    1. the 100:1 dimming ratio is limited by decoding circuit, lower than 1% duty is clamped to 1%, otherwise the offset of current sink will have large impact of output current, the current may not be regulated.
    2. lower than 10k PWM frequency is not applicable in TPS61163A.

    Actually, the resolution of TPS61163A is 9bit, which means from 1% to 100% output current, you could split in 512 steps as long as the input PWM signal supports higher than 9bit resolution.