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TPA3255: Using the TPA3255DDVR power amplifier chip, a 175W PBTL power amplifier is designed with an output load of 8Ω.

xiang tang
Prodigy 10 points
Part Number: TPA3255

Tool/software:

HI 

When designing the PBTL 175W power amplifier, I encountered problems using the TPA3255DDVR chip. PVDD 24VDC, VDD 12VDC. The load is 8Ω or two 8Ω resistors connected in parallel. Input A and Input B are set with 850Hz analog differential signal values, and then the "FAULT" indicator indicates a fault. Design the circuit schematic as shown in the PDF. And the 11th pin was damaged during the debugging process, showing a short circuit to GND. After replacing the chip, continued debugging of pin 14 also resulted in a short circuit to GND. Please inform us how to handle the DIFFERENTIAL SIGNALS OF INPUT A and INPUT B.Are there any parameters on the circuit that need to be corrected?

TOM

ETH 雾笛原理图-南华机电.pdf雾笛 背面PCB板.pdf雾笛 正面PCB板.pdf

  • 0
    TI__Genius 17960 points

    Hello,

    Thanks for reaching out. I am first reviewing the schematic and will provide feedback tomorrow. 

    Regards,
    Sydney Northcutt

  • 0 in reply to Sydney Northcutt
    Prodigy 10 points

    HI Sydney Northcutt

    Can the PBTL input signal be a mono-channel input? Do both differential signals A and B need to be input?

  • 0 in reply to xiang tang
    TI__Mastermind 20251 points

    hi, Xiang

    1.in PBTL mode, you can set one of A and B to GND. but this might affect the max output power. as input voltage be smaller than mono-channel.

    2.about the sch and pcb. below points pls be attention:

    -output LC filter, the Cap is too small. you can use 0.47uF as recommended in our DS.

    -output inductor, your sch show 10uH, but pcb show 22uH, pls notice about that the LC filter might affect FR at high band.

    -also, the inductor Isat also need to be noticed.

    -you can refer our App notes for LC fitler design.

    https://www.ti.com/lit/pdf/slaa701

    -PCB layout, i haven't see how you put you heat sink, as your output power is large, the heat sink is necessary.

    -3 large power amps be put so tighten on pcb, the thermal has a little concern. 

  • 0 in reply to Jesse Ji
    Prodigy 10 points

    HI Jesse Ji

    Thank you for your guidance. I will first optimize the circuit and plan to redesign it using only one power amplifier. May I ask if it's okay to directly ground input B through a capacitor, and connect input A to my pre-amplifier as described in the schematic diagram, as shown in the picture? That is to say, it is not necessary for the input signal to be a differential signal. What is the reason for the current 19-pin driver indicator light to be on? Regarding the capacitor, I will consider increasing its capacity. As for the heat sink, I have one on the top of the chip. Currently, the main issue is that there is no operation. After powering on, the 19-pin indicator light keeps malfunctioning, and the circuit current is 0.13A. The input voltage PVDD is 24V.

    TOM