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TPS92692-Q1: PWM input frequency range and duty range

Ryuji
Guru 20090 points
Part Number: TPS92692-Q1

Hello,

Could you please let me know the recommended PWM input frequency range and duty range?

Best Regards,
Ryuji

  • 0
    TI__Mastermind 25500 points

    Hello Ryuji-san,

    The frequency range is not really limited, the contrast ratio you can achieve just depends on the PWM frequency due to the current slew rate. If you use something low like 200Hz you can get a very wide dimming range (very small minimum duty cycle), but if you use something high like 10kHz the minimum duty cycle will be much more limited. The linearity is also better over the duty cycle range at lower frequencies.

    But I would say realistically I probably would not exceed 30kHz but would use a much lower frequency if possible, especially if I needed a wide range.

    Regards,

    Clint

  • 0 in reply to Clinton Jensen
    Guru 20090 points
    Hello Clint san

    Thank you for the reply.
    In the TPS92692-Q1 BUCK-BOOST LED DRIVER COMPONENT CALCULATOR, the recommended PWM frequency range is 10Hz to 1000Hz.
    How was this recommended frequency range presented?

    Best Regards,
    Ryuji
  • 0 in reply to Ryuji
    TI__Mastermind 25500 points

    Hello Ryuji-san,

    The 100Hz to 1kHz recommendation is to achieve a very wide dimming range with good linearity over the range. At those frequencies 1000:1 or greater is possible if well designed. But you can go higher, you will just reduce the maximum dimming range and linearity which is why the lower frequency range is recommended.

    Regards,

    Clint

  • 0 in reply to Clinton Jensen
    Guru 20090 points
    Hello Clint san,

    Thank you for the reply.
    Could you please let me know the minimum PWM dimming pulse width of TPS92692-Q1?
    I understood that the specification is depending on FET.
    However, I would like to calculate minimum duty with PWM frequency.
    Could you please present calculation example?

    Best Regards,
    Ryuji
  • 0 in reply to Ryuji
    TI__Mastermind 25500 points

    Hello Ryuji-san,

    I do not have those calculations and it would depend on a lot of factors and tolerances so it should really be tested. But in my bench testing I have found about 10us is pretty reasonable for most applications.

    Regards,

    Clint