2.3 Backlight Control

The backlight management of the LCD Module is ensured by a Microchip MIC2289 PWM boost-switching regulator optimized for constant-current white LED driver applications.

The MIC2289 implements a constant frequency 1.2 MHz PWM control scheme. The added benefit of the constant frequency PWM scheme in comparison to variable frequency is much lower noise and input ripple injected to the input power source.

For more details on the MIC2289 backlight driver, see Additional Resources.

Figure 2-3. MIC2289 Backlight Driver Schematic

By default, after MPU NRST is released, the backlight driver is off and a command on LCD_BACKLIGHT_PWM must be applied to power on the LCD Module backlight.