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TPS54200: I have some questions about TPS54200.

R.Fukunaga
Expert 1195 points
Part Number: TPS54200
Other Parts Discussed in Thread: TPS92200

Hi all

I would like to ask you some question about TPS54200.

・What is the Min the value of Falling Vpwm? (typ=1.8V)

I would like to know Analog dimming-mode threshold (Vadim).

・What are the recommend values of the Lmin and Cout for Kind value between 0.2 and 0.4?

       

・I would like to ask about Fpole.

       

Fpole is recommended to be 2kHz in analog dimming mode and 4kHz in PWM dimming mode.

Is it the same when the PWM duty cycle is 100%?

Kind regards


Ryusuke

  • 0
    TI__Genius 16630 points

    Hi Ryusuke,

    I am out of office for business trip today and I will reply to you tomorrow when I am back to office. Thanks for your patience.

    Best Regards,

    Steven

  • 0 in reply to Steven Li
    Expert 1195 points

    Hi Steven,

    Thank you for your reply.

    I look forward to hearing from you.

    Ryusuke

  • 0 in reply to R.Fukunaga
    TI__Genius 16630 points

    Hi Ryusuke,

    Thanks for your understanding. Will update here later.

    BR,

    Steven

  • 0 in reply to Steven Li
    TI__Genius 16630 points

    Hi Ryusuke,

    • For PWM/analog dimming mode selection, you can refer to 8.4.2 Mode Detection from the datasheet.
    • For analog dimming operation, you can refer to 8.4.3 Analog Dimming Mode Operation from the datasheet.
    • For recommended values of the Lmin and Cout, that will be based on your input voltage, output voltage and current.
    • The pole value is recommended here in order to assure the loop stability among the full dimming range.

    Best Regards,

    Steven

  • 0 in reply to Steven Li
    Expert 1195 points

    Hi Steven

    Thank you for your reply.

    I number the questions.

    ①When transitioning from Analog dimming-mode to PWM dimming mode, I think it should be less than 1.8V. (because of Falling Vpwm is 1.8V)

    but 1.8V is typ value. I would like to know Min value of Falling Vpwm.

    ②I am confirming the details of Vin, Vout and Iout.

    It is necessary to change Kind value by mode?

    ③2kHz for analog dimming mode applies to 100% PWM mode?

    4kHz for PWM dimming mode applies to 100% PWM mode?

    Which is better 2kHz or 4kHz?

    Best rigards,

    Ryusuke

  • 0 in reply to R.Fukunaga
    TI__Genius 16630 points

    Hi Ryusuke,

    1. Sorry but min/max value of V_ADIM is not characterized. We may need to do some test / tracking to find that. If both PWM and analog dimming mode is needed, then I recommend you switch to the newer generation - TPS92200D1. Or we have a newer device that can implement PWM and analog dimming at the same time. (For TPS54200/TPS92200, you can only implement one dimming method at one time.)
    2. Not necessary.
    3. As I have mentioned, the pole value is recommended here in order to assure the loop stability among the full dimming range (0 - 100%). 

    BR,

    Steven

  • 0 in reply to Steven Li
    Expert 1195 points

    Hi Steven,

    ①Thank you for your reply. I understood.

    ②I checked it. Vin=24V, Vout=9~10V, Iout=150mA.

    What are the recommend values of the Lmin and Cout for Kind value between 0.2 and 0.4?

    ③My customer uses 100% PWM mode. So Fpole value is 2kHz. There're no problems, right?

    ④I would like to ask you ceramic capacitor between the BOOT and SW pins.

    Should I design this ceramic capacitor to be 0.1μF at 6V in consideration of DC bias?

    Best Regards,

    Ryusuke

  • 0 in reply to R.Fukunaga
    TI__Genius 16630 points

    Hi Ryusuke,

    2. You can refer to Section 9.2.1.2 Detailed Design Procedure from the datasheet.

    3. A pole of 4kHz is suggested here for PWM dimming mode.

    4. You should consider the DC bias.

    BR,

    Steven

  • 0 in reply to Steven Li
    Expert 1195 points

    Hi Steven,

    3. My customer uses 100% on duty with PWM dimming mode. should Fpole value be 4kHz even in this case?

    Best Regards,

    Ryusuke

  • 0 in reply to R.Fukunaga
    TI__Genius 16630 points

    Hi Ryusuke,

    Do you mean the customer will stay in 100% on duty at all time? If this is the case, then 2kHz Fpole is more appropriate here.

    BR,

    Steven