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TPS92641EVM: Modifying EVM for 24V input

Part Number: TPS92641EVM
Other Parts Discussed in Thread: CSD18504Q5A, TPS92641

Hi team,

Could you please let know how to modify the EVM to operate it with 24V input?

What component should be modified to extend VIN range lower?

Regards,

Itoh 

  • Hi since this period is during Chinese mid-autumn festival, out expert will reply you after this Wed. 

  • Hi Frank-san,

    OK, I understand.

    My customer is trying to use below parameters for the modification. Could you please review it?

     

    Vin  24.0V±1.2V

    Vout  16V (Vf=3.2V ×5 series)

     

    Rvout1  54kΩ

    Rvout2  10kΩ

     

    Con   1μF

     

    fsw  1MHz

     

    Ron  6.4kΩ

    RIADJ1  10kΩ

    RIADJ1  20kΩ

     

    L  20μH

    (iL-PP - 296.3mA)

     

    rD 3.2Ω

     

    Cout 0.01uF×4 parallel

    (Cout = 38.6nF)

     

    ILED 1A

     

    RUDIM1 100kΩ

    RUDIM2 3.0kΩ

    RUDIM3 18.0kΩ

    Also, please help to address below questions.

    Can TPS9241 drive >1A if right FET is selected? My customer should use CSD18504Q5A.

    Do you think it can drive up to 15A? 

    Also, the FET is required for shunt dimming as well.  Is CSD18504Q5A good for the shunt dimming?

    Is there any component required between SDRV and Qsdim?

    When using shunt FET dimming with SDIM, how should the UDIM pin terminated?

    Is it recommended to input same signal as SDIM pin?

      

    Regards,

    Itoh

  • Hi Itoh,

    Please send the schematic to me.

    Yes, TPS92641 could support >1A output. When shunt dimming, the UDIM should be pull-up.

    Robin

  • Hi Robin-san,

    My customer is trying to modify the EVM, so please check the EVM schematic.

    The above parameters are what my customer want to use on the EVM.

    You can find them from the datasheet.

    Best regards,

    Itoh

  • Hi Itoh,

    These parameters seem OK. 

    Robin

  • Hi Robin,

    Thank you for your kind review.

    Do you think they should use a gate resistor at SDRV?

    Regards,

    Itoh 

  • Hi Robin,

    My customer is modifying the design (EVM modification) as below:

      

    Vin  24.0V±1.2V

    Vout 17V (Vf=3.0V ×5-series + 12Ω balance resistance) (modified from 16V )

     

    Rvout1  56kΩ (modified from 58kΩ)

    Rvout2  10kΩ   

     

    Con   1μ

     

    fsw  280kHz (modified from 1MHz)

     

    Ron  24kΩ (modified from 6.4kΩ)

    RIADJ1  10kΩ

    RIADJ1  20kΩ

     

    L  68μH (modified from 20μH)

    (iL-PP - 306.4mA)

     

    rD 3.2Ω

     

    Cout 0.1uF0.47uF (modified from 0.01uF×4)

    (Cout = 142nF)

     

    ILED 1A

     

    RUDIM1 100kΩ

    RUDIM2 3.0kΩ

    RUDIM3 18.0kΩ

     

    By the above modification, my customer cares if 5LEDs should work with 280kHz switching frequency.

    Could you please help to check it?

    Best regards,

    Itoh

  • Hi Itoh,

    280kHz should work  normally. BTW, TPS92641 is used for what application? And why switching frequency is change to 280kHz from 1MHz?

    Robin