LP8556: Seeking LED driver with following requirements

ameenu vm

Prodigy 155 points

Part Number: LP8556
Other Parts Discussed in Thread: LM36922, TPS61042, TPS61043, LM36274

Hi,

Seeking LED driver with following requirements:

1. I2C control

2. Analog brightness control (that needs to be completly turn off at one end)

3. LED will be 2S2P Configuration ( There will be 4 LEDs, Out of that, 2 LEDs will parallel and that 2 set will be series. Hence this setup will be having single common anode and single common cathode)

4. Maximum Current consumption is around 20mA.

5. Forward Voltage is around 6V.

6. Medical grade component

It is highly appreciated, if you guys assist me for proper component identification.

over 2 years ago

0 LeonardEllis over 2 years ago

TI__Guru 71526 points

Hello Ameenu,

Our experts for this device are currently celebrating Chinese New Year. Someone will respond to you next week.

Regards,

~Leonard

0 Mason Wang over 2 years ago

TI__Genius 9630 points

Hello Ameenu

What is the input voltage requirement here?

From your 2S2P configuration, seems only one channel is needed?

0 ameenu vm over 2 years ago in reply to Mason Wang

Prodigy 155 points

Hi Mason,

input voltage can be up to 5V (1.8 or 3.3V or 5V)

Yes, one channel is enough.

Thanks and Regards,

Ameenu

0 Mason Wang over 2 years ago in reply to ameenu vm

TI__Genius 9630 points

hi ameenu

We have limited backlight devices supporting input voltage low to 1.8V, only TPS61042, TPS61043, but have no I2C control. For input voltage higher, Lm36922, lm36274 can be options.

0 ameenu vm over 2 years ago in reply to Mason Wang

Prodigy 155 points

Hi Mason,

Thank you for your valuable response.

It looks like LM36922 meets our requirement. But one more concern is whether it is pure current control or not. we need pure current control.

Thanks and Regards,

Ameenu

+1 Mason Wang over 2 years ago in reply to ameenu vm

TI__Genius 9630 points

hi ameenu

This device is pure current control, which is also known as pure analog dimming.

0 ameenu vm over 2 years ago in reply to Mason Wang

Prodigy 155 points

Hi Mason,

The total string voltage is 6V. So boost voltage will be 6.23V as per the equation which is mentioned in page 29 I hope it can boost from 5V input supply to 6.23 and there is no minimum boost voltage for this LM36922. right?

Thanks and Regards,

Ameenu

0 Mason Wang over 2 years ago in reply to ameenu vm

TI__Genius 9630 points

hi ameenu

for 5V input and 6.23V output, the duty cycle is roughly around 20%. I think there is no problem using LM36922.

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LP8556: Seeking LED driver with following requirements