LP8866S-Q1: PWM Dimming resolution

Ully Raihany

Part Number: LP8866S-Q1
Other Parts Discussed in Thread: LP8866-Q1

Tool/software:

Hi all

i have a questions regarding the LP8866-Q1 BOOST LED Driver Design Tool.

The image below, which I marked in red, has the Desired LED Dimming Frequency and the Input the PWM Dimming Frequency (The external PWM signal from MCU). Does the PWM input from MCU have to be the same as the desired Dimming Frequency?

for example? if we set the input PWM 244Hz, will the desired PWM Frequency be 244Hz too?

And the other Question from the datasheet, it said that the LED Driver feature 12-bit analog dimming,

what is the different between this:

and how to set the analog dimming?

Thank you

7 months ago

0 Zhiqian Wu 7 months ago

TI__Mastermind 31175 points

Hi, Ully

If you choose the phase shift dimming, the input PWM frequency has no relationship with the output dimming frequency. The frequency is set by resistor.

For resolution, it is the PWM dimming resolution, analog dimming is still 12bit.

0 Ully Raihany 7 months ago in reply to Zhiqian Wu

Intellectual 285 points

Hi Zhiqian,

I see, what if we use the Hybrid Dimming Mode? will it also depend on our resistor settings?

and for the resolution, example, if we set the R_PWM_FSET to 4.75Ohm = 305Hz = PWM dimming resolution 16 bits.
the analog dimming still 12 bit? what's the different between this?

0 Zhiqian Wu 7 months ago in reply to Ully Raihany

TI__Mastermind 31175 points

HI, Ully

I will reply you late.

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LP8866S-Q1: PWM Dimming resolution