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Original question:

LP5024: LP5024_Init or Control

LP5024: LP5024 solve flicker issue (Phase Shift)

Kami Huang60
Genius 3830 points
Part Number: LP5024
Other Parts Discussed in Thread: TLC5947,

Dear Sir/Ms.

I got customer complain about TLC5947 flicker issue. 

The end customer uses the camera to take light from the TLC5947. The screen light that the user sees the camera will flicker.

My customer are searching whether there is higher frequency than 4M Hz on PWM LED Driver IC, or other solution without PWM dimming. Below IC that has 4MHz Internal Oscillator is used in existing product.

I recommend using the LP5024 because the LP5024 has Phase shift technology. Can PWM Phase shift solve this problem?

Best Regards,

Kami Huang

  • 0
    TI__Genius 11836 points

    Hi, Kami,

         Can you share schematic of your typical application circuit? Can you explain it in  more details about flicker issues of TLC5947? These information will be helpful for solving problems.

  • 0 in reply to Charles-Chen
    Genius 3830 points

    Hello Charles,

    - Detailed application specifications:
    - LED string :
      Cold: 6LED series/5LED series
     Amber: 5LED series/ 5LED series
    - Current : 20 mA
    - PWM frequency : ~976Hz
    Duty : (1), 1 ON, 4095 OFF ; (2), 2048 ON, 2048 OFF (3), 4000 ON, 96 OFF .

    Best Regards,

    Kami Huang

  • 0 in reply to Kami Huang60
    TI__Genius 11836 points

    Hi, Kami,

         Do flicker issues happen in all three duty cycles（1/4096，2048/4096，4000/4096)?  The PWM frequency of LP5024 is 29 kHz, which may improve the problem. However, Duty cycle of 1/4096 is achieved by dithering in LP5024, which is an approximation result for 12 bits of PWM grayscale control.

         PWM phase shift mainly aims to reduce the amplitude of peak load current. Low PWM frequency may be the main reason causing flick issues when you shoot with a camera, even if you use device in a correct way.

         

  • 0 in reply to Kami Huang60
    TI__Genius 11836 points

    Hi, Kami,

         I'll close this thread due to inactivity and if you have more questions please reply to it directly and it will open again.