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Original question:

UCC25660: ucc25660

UCC25660: ucc256601ddbr

ADITYA ARYA
Prodigy 50 points
Part Number: UCC25660
Other Parts Discussed in Thread: UCC28180

Tool/software:

Dear TI Team ,

We are using ucc256601ddbr LLC controller with ucc28180 PFC controller for 1k.watt 64V ​​-15.6A EV charger (48v battery).

design is in in HF burst up to 6A, and when we put load 7A the output voltage decreases.

for reference i am attached some waveform like without load and with load of 5A

i am attached schematic and tool also, please provide solution or suggestion asap 

   <------- without load , Ch4- green waveform is feedback, CH 2-blue waveform is ISNS , CH1 - yellow is low side gate,  CH3 -pink is high side gate

<------ with trigger mode, Ch4- green waveform is feedback, CH 2-blue waveform is ISNS , CH1 - yellow is low side gate,  CH3 -pink is high side gate

<------- with 5A load, Ch4- green waveform is feedback, CH 2-blue waveform is ISNS , CH1 - yellow is low side gate,  CH3 -pink is high side gate

final UCC25660x_CALC_1.0 (2)( 64v15.6A)1000 watt_1805.xlsxPFC dsn.pdfLLC dsn.pdfPOWERSUPPLY dsn.pdf

  • 0
    TI__Guru 71575 points

    Hello,

    Your inquiry is under review and I will get back to you shortly.

    Regards,

  • 0 in reply to Mike O'
    TI__Guru 71575 points

    Hello,

    When it comes to evaluating why the output is dropping out at 7 A.  I think it is a good idea to evaluate the controller and waveforms where the design is going out of regulation.

    When the design is running at 7 A is the PFC output regulating the LLC input voltage?  If it is not that might be why the design is dropping out of regulation.

    Regards,

  • 0 in reply to Mike O'
    Prodigy 50 points

    Hello sir,

    we checked controller all pin levels according to design tool and seems fine.

    And design is in in HF burst up to 6A, and when we put load more then 7A the output voltage decreases.

    when design running on 7A to 8A output decreases so much and at the time PFC voltage is good. (390V)

    I am  sharing waveform with 6A and with 8A and video for reference and design tool of ucc256601

    <----yellow Ch1= feedback , RED CH3= high side gate, Green CH4= low side gate , this waveform at  load 6A  and output voltage is 64.3v

    <----yellow Ch1= LL pin, blue Ch2=BLK, RED CH3= high side gate, Green CH4= low side gate , this waveform at  load 6A  and output voltage is 64.3v

    <----yellow Ch1= IC VDD pin, blue Ch2=ISNS, RED CH3= high side gate, Green CH4= low side gate , this waveform at  load 6A  and output voltage is 64.3v

    <----yellow Ch1= IC VDD pin, blue Ch2=ISNS, RED CH3= high side gate, Green CH4= low side gate , this waveform at load 8A  and output voltage is 61.0

    <----yellow Ch1= FB pin, blue Ch2=BLK, RED CH3= high side gate, Green CH4= low side gate , this waveform at load 8A  and output voltage is 61.0

    <----yellow Ch1= LL pin, RED CH3= high side gate, Green CH4= low side gate , this waveform at load 8A  and output voltage is 61.0

    7077.final UCC25660x_CALC_1.0 (2)( 64v15.6A)1000 watt_1805.xlsx

    Thanks

    Aditya 

  • 0 in reply to ADITYA ARYA
    TI__Guru 71575 points

    Hello,

    Is the design still operating in burst mode at 7 A?

    If it is the burst mode will be acting as a power limiter.

    You might need to adjust your LL resistor divider so the converter will come out of burst mode at 6 A so the output can regulate at 7 A.

    Regards,