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LP8860-Q1: Panel LED voltage

Josh5566
Prodigy 170 points
Part Number: LP8860-Q1

The panel datasheet indicates that  the LED voltage VF max. is 60V and we will deside using the LP8860-Q1 for the solution.

However, the simplified schematic of LP8860-Q1 specifies voltage of up to 48V. How can we design the 60V of LED voltage once using the LP8860-Q1?

Regards.

  • 0
    TI__Mastermind 22695 points

    Hi, Josh

    May I ask why you choose LP8860? It is the old version of our device, we highly recommend to use LP8864.

    And for your design requirement, as our device is a controller. We can support 60V with additional action.

    First, DISCHARGE should not be connect. And then set the FB ratio as the target of 60V. And then add a 10M resistor to each OUT pin. Then our device can support higher output.

    Pls understand if all the LED in one string is short(60V connect to OOUT pin directly), our device may see problems in this design. 

  • 0 in reply to Zhiqian Wu
    Prodigy 170 points

    Thanks for your prompt response to my inquiry. Because this old project been used LP8860 and the panel will EOL.

    Then we will replace new panel for continued use with LP8860.

    For LP8860-Q1

    1. In Figure 21, what are the values of the two resistors in the FB Divider?

    2. In section 9.2.3 High Output Voltage Application, following 9.2.2.1 Design Requirements Feedback voltage divider: R1DIV = 30 kΩ, R2DIV = 150 kΩ, how do we calculate VOUT: Up to 60 V?

    3. Address 0x73: 0xDF deduces BOOST_INITIAL_VOLTAGE[5:0] = 011111 = 31.5V, is this the FB voltage?

  • 0 in reply to Josh5566
    TI__Mastermind 22695 points

    Hi, Josh

    Understand about your status.

    As it is a new panel, pls consider for a new device to support. LP8860 cannot support the high output voltage, because the FB divider is integrated.

    LP8864 can support as I mentioned above.

  • 0 in reply to Zhiqian Wu
    Prodigy 170 points

    Thanks for your suggestion. We have decided use new device and redesign pcb.

    Additionally, we want to select led driver without software progrmming, swtiching frequency controller by resistor.

    Would you like to recommend other LED driver?

    • VIN : Operation 5V to 17V
    • PWM
    • Enable
    • Switching frequency above 1.3MHz, controller by resistor.
    • spread spectrum

  • 0 in reply to Josh5566
    TI__Mastermind 28740 points

    Hi Josh,

    Our expert is out of office and will give you feedback when comes back.

  • 0 in reply to Patrick Yao
    TI__Mastermind 22695 points

    Hi, Josh

    Pls consider LP8864S as the solution, and additional action is shown in below:

    And for your design requirement, as our device is a controller. We can support 60V with additional action.

    First, DISCHARGE should not be connect. And then set the FB ratio as the target of 60V. And then add a 10M resistor to each OUT pin. Then our device can support higher output.

    Pls understand if all the LED in one string is short(60V connect to OOUT pin directly), our device may see problems in this design.