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LP8863-Q1: LP8863-Q1 High dimming ration conditions

Terry Wu2
Expert 2110 points
Part Number: LP8863-Q1

Hello Sirs,

May I know is there any conditions to achieve 32000:1 dimming ratio ?

Only 152Hz PWM frequency ?  Both internal PWM or external PWM input also OK?

For this dimming ration , is there boost switching frequency limitation ? Need  BST_SYNC input or not ?

Can LP8863 support different LED Vf for LED0~LED5 ?  ex: 10 LED string on LED0 and 3 LED string for LED1~5 .

Can external power supply implement this inquiry ?

Many thanks !

  • 0
    TI__Prodigy 670 points
    1. It's recommeded to use I2C or SPI interface to control the brightness to realize 32,000:1 dimming ratio. If PWM input on PWM pin has to be used for brightness control, the frequency of PWM input needs to be lower than 152Hz.
    2. For dimming frequency, whatever the dimming frequecy is set by resistor on PWM_FSET pin, the actually dimming frequency will be down to 152Hz for 32,000:1 dimmin ratio.
    3. No limmitation for boost switching frequency. It doesn't need to BST_SYNC.
    4. LP8863 can support differnt LED numbers on differnt string. But the extra power supply need to be provided. e.g. LP8863 boost to supply 10 LED string on LED0, and extra power supply to supply 3 LED string for LED1~5. For 10 LED string, the adpative boost output regulate the proper votlage to 10 LED.
  • 0 in reply to Xianghao Meng
    Expert 2110 points

    Hi Xianghao,

    Thanks your reply !

    May I know device initial time of LP8863 as datasheet Fig.28 if we need i2c/spi control it during standby time ?

    TKS!