Charge Pump for Backlight/Flash/RGB LEDs with Safety Timer

Active: In Production.

The MAX8879 provides complete light management for main display backlight, subdisplay backlight (or RGB indicator), and white LED camera flash with regulated constant current up to 610mA total. By utilizing adaptive 1x/1.5x/2x charge-pump modes and very-low-dropout current regulators, it achieves high efficiency over the full 1-cell Li+ battery input voltage range. The 1MHz fixed-frequency switching allows for tiny external components while the regulation scheme is optimized to ensure low EMI and low input ripple. An integrated derating function protects the LEDs from overheating during high ambient temperatures.

The MAX8879 features an internally trimmed reference to set the maximum LED current. An I²C serial port is used for on/off control and setting the LED currents in 32 linear steps for main, sub/RGB, and movie. When using the RGB indicator, the I²C port provides 32k colors and programmable ramp-up/down rates. The camera flash for flash-mode operation is enabled by an active-low signal on the active-low FSH pin. A safety timer is activated on the falling edge of active-low FSH, which has an I²C-adjustable (programmable) period of no timer, 0.5s, 1.0s, or 2.0s (default). If the safety timer period expires, both flash and movie modes are disabled.

Download Rev 0 (PDF, 588kB) E-Mail