LP8556: LP8556 to integrate multi-channel control

Hi JK,

I am a little confused, if you already used 3 LP8556 for 3 LED strings, so why don't you just use the Vboost directly?

BR

Patrick

Hi Patrick

Thanks for your reply.

The sink current of LP8556 support up to 300mA (50mA*6) , The total current for RGB reaches 900mA  (RGB led is common anode type)

I'm not sure over the Vboost supply capability?

So want to further confirm that external power supply is feasible?

BR

JK

Hi JK,

What will be the input voltage if you use LP8556 to generate the Vboost? I can help to calculate if this is over spec for our IC.

BR

Patrick

Hi Patrick,

input voltage = 12V

thank you.

BR

JK

Hi JK,

Are the RGB LED strings have the same forward voltage ~12V or there are some differences?

BR

Patrick

Hi Patrick

Here is LED spec:

Because the RGB LED is 1S3D *20sets, so the forward voltage is some differences. 

G: 8.4V ~ 10.8V

B: 5.4V ~ 7.8V

B: 8.4V ~ 10.8V

BR

JK

Hi JK,

You can use LP8556.

BR

Patrick

Hi Patrick

Thanks for your reply.

So, can we use the external 12V power supply structure above, right?

BR

JK

Hi JK,

You can use external 12V, but it is still recommended to use LP8556 Vboost directly because this IC is available of adaptive headroom control. With external supply the headroom voltage might not be enough to regulate the LED current.

BR

Patrick