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LP8863-Q1: Dither

Fandy
Expert 2285 points
Part Number: LP8863-Q1

Hello

1. I am confused about Dither function even I have read the 8.3.6.4 in datasheet ,Could you explain it to me more detail

"When the 1-bit dither is selected, the width of every second PWM pulse is increased by one LSB (one 20-MHz
clock period). When the 3-bit dither is selected, within a sequence of 8 PWM periods the number of pulses with
increased length varies: dither value 000 - all 8 pulses at default length; 001 - one of the 8 pulses is longer; 010 -
two of the 8 pulses are longer, etc., until at 111 seven of the 8 pulses have increased length. Figure 20 shows
one example of PWM output dither."

2.LP8863's LED PWM frequency could be setted by external resistor, so higher LED PWM frequency could be better or lower LED PWM frequency could be better ? 

  • 0
    TI__Expert 5475 points
    Hi Fandy,

    1. Dither function is used to increase the dimming resolution which is limited by the oscillator clock. If dither function is disabled, the on time of each PWM period is the same. If 3-bit dither is selected, 0~8 of every 8 PWM cycle may be increased, so that the dimming resolution can be increased.
    2. When selecting lower PWM frequency, the dimming resolution can be higher. When selecting higher PWM frequency which is much higher than the refresh rate, there will be less concern on "waterfall" effect.