ZHCSCK8H May 2014 – April 2025 LP8860-Q1
PRODUCTION DATA
In Display Mode LED outputs are configured to power an LCD backlight. Maximum current per string is set by RISET; alternatively, through a user-programmable EEPROM value.
Brightness is controlled with PWM input or I2C/SPI register writes. An optional sloper feature enables automatic smooth transition between brightness levels. Sloper time can be programmed to EEPROM registers, and an advanced slope feature allows smoother response to eye compared to traditional linear slope.
Outputs are controlled with a Phase Shift PWM (PSPWM) Scheme. Due to the phase shift between the outputs they are not activated simultaneously which brings several benefits:
PWM output frequency is set with EEPROM registers from 4.9 kHz to 39 kHz. Selecting output frequency depends on the number of strings used, system requirements for the frequency, and desired dimming ratio. Dimming resolution is a function of PWM output frequency — the higher the frequency, the lower the resolution.
User can choose to increase resolution by:
Increasing internal clock frequency increases device current consumption.
In high-quality display systems an "anti-waterfall" feature may be required. The LP8860-Q1 supports this by offering output synchronization to the LCD refresh signal through VSYNC input. VSYNC input is synchronized to outputs through internal PLL; EEPROM and filtering are described in later sections.