LP8556: Can the channel number of LP8556SQX-E08/NOPB be changed to 6?

Reagan Li

Part Number: LP8556

Hi team,

Customer got a question about the compatibility design for the LP8556SQX-E08/NOPB and LP8556SQX-E09/NOPB.

The E08 version default channel number is 4 while that of E09 is 6.

1. Could we set follow EPROM setting of LP8556SQX-E09 and change the LP8556SQX-E08 register using I2C to enable 6 channels?

2. If we can make the LP8556SQX-E08 enable 6 channels. We should reprogram LED_EN bits to change LED string counts enabled and set PS_MODE bits accordingly ,right ?

3. To reprogram the register , we should power up the VDD and not enable the EN/VDDIO , right ? As the config registers are not accessible in the Active Mode

Thanks!

Reagan

over 4 years ago

+1 Hardy Wu over 4 years ago

TI__Genius 12915 points

Hi Reagan,

1. Could we set follow EPROM setting of LP8556SQX-E09 and change the LP8556SQX-E08 register using I2C to enable 6 channels?

Yes you can write the value in register A3h and A5h when powering up to enable 6 channels for E08 version.

2. If we can make the LP8556SQX-E08 enable 6 channels. We should reprogram LED_EN bits to change LED string counts enabled and set PS_MODE bits accordingly ,right ?

LED_EN bits are default as 1. These bits are AND with the internal LED enable bits that are generated with the PS_MODE logic. So only change PS_MODE bits is OK.

3. To reprogram the register , we should power up the VDD and not enable the EN/VDDIO , right ? As the config registers are not accessible in the Active Mode

EN/VDDIO is the power supply reference for interface pins. So it need to be enabled before writing I2C commands. You could pull PWM input low when reprogram the registers.