LP8556: DRIVER_HEADROOM and LED_COMP_HYST

K.Yaita

Part Number: LP8556

Hi Team,

I understood DRIVER_HEADROOM and LED_COMP_HYST is used to decide VBOOST voltage in adaptive control.
What situation should we change these register value from default value?
I would like to know the criteria to change these registers.

Best Regards,
Yaita / Japan disty

over 7 years ago

0 Angelos Tsiros over 7 years ago

TI__Intellectual 2140 points

Hi,

Thank you for your interest in the LP8556.
Due to holiday in the US, the response to your questionS will be a little delayed. Someone will respond on Monday November 27, by end of US business day.

Regards,
Angelos Tsiros

0 Caryss Li over 7 years ago

TI__Expert 4550 points

Hi Yaita,
Usually, the headroom voltage is related with the output current of each channel. Higher current needs higher Headroom voltage. the HYST voltage determines when the Vboost is too high and adjust the control loop to reduce ourput voltge. Higher HYST may make the boost output voltage loop less sensitive but leads to higher power loss.

0 K.Yaita over 7 years ago in reply to Caryss Li

Guru 29720 points

Hi Caryss-san,

Thank you for your kind support.
Why does higher current need higher Headroom voltage?
Could you please explain it?

Best Regards,
Yaita

0 Caryss Li over 7 years ago in reply to K.Yaita

TI__Expert 4550 points

Hi Yaita-san,
This is the characteristic of current sink. When high output current is needed, if the headroom voltage is not enough, the current you need cannot be provided.

Power management

Power management forum

LP8556: DRIVER_HEADROOM and LED_COMP_HYST