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Original question:

TPS23754 Regarding to Voltage Range of Vc

TPS23754EVM-383: Power management forum

Ben Chen75
Prodigy 250 points
Part Number: TPS23754EVM-383
Other Parts Discussed in Thread: TPS23754

Hello,

According to the specification of TPS23754, the operating input range of VC is between  8 ~ 18V.

The design of TPS23754-EVM shows that the turn ratio between the Primary and AUX of flyback transformer is 2:1.2. 

How can we make sure that VC can be within 15V if Vin is up to 57V. Is there any formula to calculate the voltage

of VC? Dose it refer to Secondary winding? 

Best Regards,

David

  • 0
    TI__Mastermind 21320 points

    Hello David,

    This node is switching, so the voltage is not only a ratio of the transformer. The voltage on VC is related to the duty cycle as well:

    V_c=  V_in  * (D/(1-D)  ) *  N_A/N_P  

    If it helps, Think about how the output voltage of 12V is maintained for the input range. In the same way VC can be maintained over an input range. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • 0 in reply to Michael Pahl
    Prodigy 250 points

    Hello Michael,

    Got! Thanks a lot!

    Best Regards,

    Ben