LP8555: LED per channel

jung tae park

Prodigy 110 points

Part Number: LP8555
Other Parts Discussed in Thread: LP8556

Hi
I am trying to design the LP8556.
I'm going to use the red LED (VF = 2V)

The current is about 10 mA to 20 mA per channel.

I want to control a total of 78ea LEDs with 13ea red LEDs per channel on the LP8556.
Is there a problem?

How many serial connections can be used per channel?

We ask for confirmation.

over 5 years ago

0 Sean Zhou over 5 years ago

TI__Mastermind 22745 points

Hi Jung,

That really depends on the input volatge and maximum current and LED forward volatge per string. There are two factors to limit the LED counts per string:
1. The OVP volatge is about 43V, that means the led counts up to 21;
2. But the internal current limit will limit the total LED counts since the total power. If you can supply the input voltage range, I can help to give a quick calculation to help get the reasonable counts.

Regards
Sean

0 jung tae park over 5 years ago in reply to Sean Zhou

Prodigy 110 points

Hi
The input voltage of LP8556 will be 3.7V ~ 4.2V
Thank you.

0 Sean Zhou over 5 years ago in reply to jung tae park

TI__Mastermind 22745 points

Hi Jung,

I have taked a quick calculation, the maximum LED counts for per string with 3.7V input voltage is about less than 12(BGA package) or 16(QFN package)。 So please be careful with your design.

Regards
Sean

0 jung tae park over 5 years ago in reply to Sean Zhou

Prodigy 110 points

Thank you for quick response.
Have a good day.

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LP8555: LED per channel