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PMP9770: LCD bias application

Jeff YANG
Mastermind 7865 points

Part Number: PMP9770

Hi,

For PMP9770 reference design, is possible to change voltage to support below LCD bias power?

1. For AVDD, we should change FB divider resistor to change output voltage.

2. For VGH/VGL, is it change D2/D3 zener diode to change voltage?

Thanks!

Jeff

  • +1
    TI__Genius 16285 points

    Hi Jeff,

    1. Is the VDD the input voltage?

    2. For AVDD, it is sure that it can output 7.5V to 8.5V. For example, let's set the output to be 8V.

    3. For VGH, it needs a charge pump connected to reach 2*8V=16V.

    Using a D2 Zener diode, a voltage lower than 16V can be outputted(meet demand 13 to 17V)

    4. For VGL, original circuit is not enough as it can only output -8V.

    We need a negative charge pump to output -16V(just like positive charge pump, see below), then using a Zener, -13V can be outputted.

    5. For the current and voltage range, it needs to be re-calculated.

    Please give out the current of every channel and double check the voltage range.

    6. I'm not familiar with LCD application and please tell more about the current 750mA and 10.5V.

    Best Regards,

    Fergus