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TPS92691: Des it be with dimming mode? do we have dimming mode buck boost? or led friver?

Shuang Feng76
Expert 3310 points
Part Number: TPS92691
Other Parts Discussed in Thread: LM5118, , TPS92692

Requirement:

1. Dimming mode and PWM dimming, 30V~60V input, output 57V2A (MAX, 1.8a is also ok)

2. PWM dimming frequency of 120Hz,Dtuty= about 35%.

This requires buck-boost IC with dimming function.

If there is no such dimming IC,  is there simple buck-boost controller with higher voltage pressure (does LM5118 be Ok for this application?).

  • 0
    TI__Mastermind 18890 points
    Hi Shuang Feng,

    The TPS92691 will not be able to handle the 120KHz dimming that you are requesting...This is quite high. I do not know of any of our product line part that can handle this.

    Thanks Tuan
  • 0 in reply to Tuan Tran74
    TI__Expert 3310 points
    Hi Tuan，

    Really thanks for your help. I am sorry that the requirement with an error. they only need 120Hz, not 120KHz.
    so is there any product more suitable for this application? or do TPS92691 and LM5118 fit this application?

    Thanks & Best Regards
  • 0 in reply to Shuang Feng76
    TI__Mastermind 18890 points

    Hi Shuang Fend,

    TPS92691 or TPS92692 are suitable for this.  The maximum voltage input to our part has to be kept below 65V that is for the output voltage that is feeding back to the CSP and CSN pin.  Since input voltage can be higher than output voltage and they are high (60V) care must be taken for not exceeding the 65V limit.

    Thanks Tuan

  • 0 in reply to Tuan Tran74
    TI__Expert 3310 points

    Hi Tuan，

         I find there are two MOS used in DDRV current control. I do not understand the advantage. could we use one MOS to realize the function? the attach is the schematic.

         About the L design, is the power used instantaneous power or average power?

        Thanks for your help.

  • 0 in reply to Shuang Feng76
    TI__Mastermind 18890 points

    Hi Shuang,

    For the TPS92691, the two FET's are used to level shift the DDRV signal to drive a high high switch for PWM'ing.  You can use the TPS92692 and this level shifting is done in the controller already so you only need the PWM'ing FET.

    Unless there are certain required specification, usually for LED's you specify the output current and voltage required and this is average power. 

    Thanks Tuan