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TPS23754: Circuit with 24V output

Kaji@PAN
Mastermind 7290 points
Part Number: TPS23754
Other Parts Discussed in Thread: PMP22301, , CSD19534Q5A

Hi,

I am considering creating a circuit using the TPS23754 device.
The specifications are as follows.
I would like to create a circuit based on the reference design PMP22301, but I am also considering the following changes from this design.

(question 1)
I would like to change the transformer to 750314782 for miniaturization.
I will attach the materials.
The inductance value becomes smaller, but is it possible to change the transformer to this?

(Question 2)
I would like to add a synchronous rectification circuit using Gate2 to improve efficiency.
I would like to use the circuit of TPS23754EVM-420 shown by the red line in the figure below.
Are there any parts other than the Q1 FET that need to be changed?

(Question 3)
I think that the secondary side synchronous FET requires a voltage between DS of about 100V.
Therefore, I am thinking of using CSD19534Q5A.
Could I use this FET?
Also, please let me know if there are any other recommended FETs.

(Question 4)
Is there anything else that needs to be changed in order to perform synchronous rectification of Gate2?

(specification)
VIN : 48V
VOUT : 24V
IOUT : 1A
Topology : flyback

Best regards,

750314782.pdf

  • 0
    TI__Mastermind 21320 points

    Hello,

    (1)Please see the following application note to calculate the transformer parameters in a diode-rectified flyback: 

    As for the rest of your questions, I would not recommend a driven sync flyback for a 24V output. 

    I would highly encourage you to keep it as diode rectified. 

    Otherwise,

    (2)all of the components circled in red will need to be evaluated. 

    (3) you will need a 200V FET or higher

    (4) you will probably need to change the feedback and the output capacitance/inductance. 

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

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments