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PMP8740: Can PMP8740 supports for 58V@35A(2KW Output Power)

Chethan S
Prodigy 60 points
Part Number: PMP8740
Other Parts Discussed in Thread: UCC28951, , UCC28950

Tool/software:

Dear TI Team,

Our concern is that, PMP8740 or UCC28951 IC can support for Output Voltage 58V for Battery Charging.

In Webench Design, it is not showing design for Vout>50V. Can you please clarify the same?

If it will support means, is there any thing that need to change other than the output voltage divider resistors for 58V?

Thanks for your support in advance.

  • 0
    Prodigy 60 points

    Dear TI Team,

    Can you please reply for this Query as soon as possible. We are waiting for your response.

    Thanks in advance.

  • 0 in reply to Chethan S
    TI__Expert 5595 points

    Dear Chethan,

    As you know, PMP8740 is designed to deliver maximum 32V and 62.5A, therefore it cannot support 58Vout just by adapting the voltage divider.

    In order to supply 58V, the whole secondary side section has to be redesigned, that means a new main transformer of the DC/DC converter (the PFC stage can be left unchanged), new sync-FETs, output electrolytic capacitors, the voltage and current ratings of output inrush current and reverse polarity protection, output inductor an so on. Please refer to the documentation you can find on UCC28950 product page. If you have further questions, please let me know.

    Best regards,

    Roberto

  • 0 in reply to Roberto S.
    Prodigy 60 points

    Dear Roberto,

    Thanks for your reply.

    We are working on 58V@35A Battery Charger. We redesigned all required part as you mentioned, like transformer, Primary and Secondary MOSFET, Inductor design, Diodes Selections, etc...

    In Closed loop without load, we got the regulation for our designed output voltage 58V.

    We are facing problem in Closed Loop; Output Voltage drops when we apply load like 4A(Load resistance fixed for 58V@4A). The output Voltage is dropping to 15V around with load current consuming around 1A.

    Is Compensation design making any problem above mentioned?

    Please suggest any documents/links related to PMP8740 Compensation Design.

    Waiting for your valuable suggestions.

    Thanks for your support in Advance.

  • 0 in reply to Chethan S
    TI__Expert 5595 points

    Hi Chethan,

    Please try to understand if it's a stability problem, the constant current loop is activated or the primary side overcurrent protection is triggered.

    You can distinguish that by doing the following tests, only one test at the time, and check if something changed:

    1) Remove the constant current loop signal from the error amplifier (remove the diode or-ing CC and CV loops)

    2) Add few uF capacitors in parallel between inverting input and output of the CV error amplifier; this way your compensator will be slow, but stable

    3) Reduce (for example by 20%...30%) the current sense resistor on the output of the current sense transformer on primary side of the PSFB.

    Please let me know if any of the three tasks bring any improvement.

    Regards,

    Roberto