LP8866S-Q1: Output Current Setting

Ully Raihany

Part Number: LP8866S-Q1

Hi All,

I have some question regarding LED Driver LP8866S-Q1

1. In LP8866S-Q1 Datasheet page 26, there is a diagram for Brightness Path Diagram

If we set the method for the output current is "PWM" how can we ensure the output current will be the same as the current we have set.

For example, If I set the Current in the PWM for 100mA output current, how to ensure that the Output is 100mA?

In page 42, it has the function for LED_PWM_STATUS, so is there any way for me to make sure the output will be the same like we set on the PWM Input for the output current

2. I Would like to know what is the level of Functional Safety in this LED Driver LP8866S-Q1? Because I cannot find it in the datasheet

Looking forward for the reply,

Thank you

over 1 year ago

0 Zhiqian Wu over 1 year ago

TI__Mastermind 20855 points

Hi, Ully

what you mean about question 1? sounds like it is related with fusa.

We can provide FIT, FMD, FMEA to help you achieve system level ASIL-B.

0 Ully Raihany over 1 year ago in reply to Zhiqian Wu

Intellectual 265 points

Hi Zhiqian,

For Question 1

Yes its related to Fusa,

I want to make sure a few things about the function of each parameter in the following diagram

1. As you can see, in the Diagram it has the PWM input and PWM Detector, and in the table it has the Register name PWM_INPUT_STATUS, and LED_PWM_STATUS.

I would like to make sure, is the function of PWM_INPUT_STATUS is allows us to see the PWM value that we input, because in the diagram it has a PWM Detector?

And How about the LED_PWM_STATUS, Which part in that diagram that will allows us to know the LED_PWM_Status?

2. For LED_CURRENT_STATUS, will the result of what we input or we set on the PWM input match the LED Current status? because we want to confirm the current results for the LEDs will always match the value we set from PWM input? and which part in that diagram that will allows us to know the LED_CURRENT STATUS?

For Question 2,

Yes we need it, if you don't mind, please provide FIT, FMD, FMEA of LP8866S-Q1 for us, (Thank you)

Actually we would like to know what is the Functional Safety Level used in this LED Driver? (The example is in the picture below)

Thank you

+1 Zhiqian Wu over 1 year ago in reply to Ully Raihany

TI__Mastermind 20855 points

Hi，Ully

As I am out of office, I will give you a feedback on next week.

0 Ully Raihany over 1 year ago in reply to Zhiqian Wu

Intellectual 265 points

HI Zhiqian,

Are you back? Is there any update for my question?

+1 Zhiqian Wu over 1 year ago in reply to Ully Raihany

TI__Mastermind 20855 points

Hi, Ully

Pls give me a email, I will send you the document by email. Also, we can have more talk in FUSA topic

For PWM_INPUT_STATUS, yes, it detected the input of PWM,

For LED_PWM_STATUS, it shows the PWM output before the LED driver.

For LED_CURRENT_STATUS. it shows the current output before the LED driver.

we can support full document about FUSA capable, but the process in TI is on-going.

0 Ully Raihany over 1 year ago in reply to Zhiqian Wu

Intellectual 265 points

Hi Zhiqian,

Okay noted, I will send you an e-mail

Thank you

+1 Zhiqian Wu over 1 year ago in reply to Ully Raihany

TI__Mastermind 20855 points

HI, Ully

Glad to help you.

0 Ully Raihany over 1 year ago in reply to Zhiqian Wu

Intellectual 265 points

Hi Zhiqian,,

Thank you for your help,

By the way I have done a test to check the PWM Status, but the results of the PWM Input and PWM Output are different? is this normal for LED Driver LP8866S?