LP8860-Q1: LP8860AQVFPRQ1 cluster-mode to provide different current in its 4 channels

Sauron huang

Prodigy 180 points

Part Number: LP8860-Q1

We want to use LP8860AQVFPRQ1 cluster mode

to provide 3 channels 80 mA to backlight’s LED-string, and

another 1 channel 20 mA to logo-lighting’s LED-string.

Can we use this cluster mode to achieve our target?

Warm Regards,

Sauron

over 6 years ago

0 Shirley He over 6 years ago

TI__Expert 5475 points

Hi,

Yes, you can use LP8860 device for this application. You can set the LED_STRING_CONF[2:0] to 001 to configure the output 4 as cluster mode and set the current independently.

0 Sauron huang over 6 years ago in reply to Shirley He

Prodigy 180 points

Hi Shirley,

we used LP8860 as car display LED-driver, the LP8860 circuit as attached file.

Our architecture is LP8860 channel1 for 20mA logo-lighting's LED, and channel2~4 for backlight's LED in cluster mode.

Every LED-string has 9pcs LED, about 30V.

Please help to review and advise,

thank you.

LED-Driver_LP886.pdf

Warm Regards,

Sauron

0 Shirley He over 6 years ago in reply to Sauron huang

TI__Expert 5475 points

Hi,

Please use channel1-3 for backlighting and channel4 for the logo LED.

0 Sauron huang over 6 years ago in reply to Shirley He

Prodigy 180 points

Hi,

I had some questions about LP8860 spec.

1. in spec. page 31, what’s the VBG?

2. In spec. page31,

We choose DRV_LED_CURRENT_SCALE[2:0] =000 to get 25mA, then DRV_OUTx_CORR[3:0]=1111 to get -7.4%

So the minimum current in cluster mode is 23.15mA?

But we want 80mA/80mA/80mA/20mA

Warm Regards,

Sauron

0 Shirley He over 6 years ago in reply to Sauron huang

TI__Expert 5475 points

Hi Sauron,

1. Vbg is the bandgap voltage of the device. You can think of it as a reference voltage.
2. There’s no need to use the DRV_OUTx_CORR to get the required current. Please use <DISP_CL1_CURRENT[11:0]>, <CL2_CURRENT[7:0]>, <CL3_CURRENT[7:0]>, and <CL4_CURRENT[7:0]> to set the channel current independently.

Power management

Power management forum

LP8860-Q1: LP8860AQVFPRQ1 cluster-mode to provide different current in its 4 channels