LP8557: Question for LP8557 output in parallel usage

Jacky Wang(QD)

Part Number: LP8557

Hi Team,

Our customer wants to check if we can connect LP8557's multi-channel output in parallel as below to drive higher current LEDs, can you help to check if it works for our device?

Thanks a lot!

over 4 years ago

0 Yuting Shao over 4 years ago

TI__Genius 13001 points

Hi Jacky,

Yes, this device can be operated by this way.

Robin

0 Jacky Wang(QD) over 4 years ago in reply to Yuting Shao

TI__Genius 11600 points

Hi Yuting,

We tried this configuration on our EVM, but it doesn't work and will report errors in STATUS register. Can you help to give us some info how to configure it to work in such application?

Thanks.

0 Yuting Shao over 4 years ago in reply to Jacky Wang(QD)

TI__Genius 13001 points

Hi Jacky,

Could you please provide the STATUS register value when error happens?

Robin

0 Dimitri Georgaras over 4 years ago in reply to Yuting Shao

Prodigy 50 points

Was this issue with the device reporting an error ever resolved?

Does connecting the outputs in parallel effect the operation of the device?

Thank you,

Dimitri

0 Jacky Wang(QD) over 4 years ago in reply to Yuting Shao

TI__Genius 11600 points

Hi Yuting,

The STATUS register reported value is 0x80 under this connection, we are using below register configuration for LP8557, after enabling the backlight, LEDs will be flashing one time and then reported 0x80 value in register 0x01h. Please help to check what's the problem in here, thanks.

Configuration Sequence:
0x10 01 //Brightness Mode: Brightness Hi/Lo Reg
0x03 B0 15 //Brightness Addr 03 and 04 8.5%
0x00 2D //Enable Backlight

0 Yuting Shao over 4 years ago in reply to Jacky Wang(QD)

TI__Genius 13001 points

Hi,

As we talked about in the call, please change the PWM-analog-dimming threshold to be 0%.

Robin

Power management

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LP8557: Question for LP8557 output in parallel usage