LP8863-Q1: Dimming ratio inquiry

May

Genius 9880 points

Part Number: LP8863-Q1

Hi Team,

Good day.

Customer want to confirm the following.

1. Does lp8863 can support a dimming ratio of 32000:1. Is it a full operating frequency band?

If I'm not mistaken on this part, the dimming ratio of 32000:1, can only be used in 152 Hz. Is this correct?

2.Want to know PWM when the dimming ratio is 10000:1 and how to set fset, R_PWM_FSET?

Regards,

Maynard

over 4 years ago

0 Charles-Chen over 4 years ago

TI__Genius 11836 points

Hi Maynard，

1. Correct.

2. Why do you want to use lower dimming ratio 10000:1 rather than 32000:1. The dimming ratio will be reduced when the PWM frequency is higher. The relationship is like when the PWM frequency double compared with 152Hz, the dimming ratio will become half of the 32000:1.

0 May over 4 years ago in reply to Charles-Chen

TI__Genius 9880 points

Hi Charles,

Customer have follow up question regarding this.

Istill have doubts about lp8863. Led PWM frequency has been adjusted according to R_ PWM_ Fset (K Ω) set to 152hz, when SDO_ PWM input any frequency and duty cycle, the input SDO_ Will PWM frequency affect led PWM frequency? In other words, led PWM frequency is not affected by input SDO_ PWM frequency control?

Regards,

Maynard

0 Charles-Chen over 4 years ago in reply to May

TI__Genius 11836 points

Hi Maynard,

The device only detects the duty cycle of input PWM signal and the output PWM frequency is only set by the R_ PWM_ Fset.

0 yinglei_li li over 4 years ago in reply to Charles-Chen

Hi Charles:

If the device only detects the duty cycle of the input PWM signal, when SDO_ PWM frequency is very high, duty cycle is very small, whether IC detection will misjudge

0 Charles-Chen over 4 years ago in reply to yinglei_li li

TI__Genius 11836 points

There are PWM input frequency range and PWM resolution in the page 10 of the datasheet.

0 yinglei_li li over 4 years ago in reply to Charles-Chen

Hi, Charles：

As for the peripheral circuit of lp8863, please check it. How can I contact you through e-mail address? Sorry, the company requires that the drawings be kept confidential and cannot be uploaded to the forum. Of course, you can send an email to (yinglei)_ li@tianma.cn ）