ADI Introduces New Charge Pump Regulator

Analog Devices' new ADM8845 charge pump regulator offers the most accurate backlighting in tiny color TFT displays for mobile phones, PDAs and digital cameras. The device uses advanced charge pump technology, which can drive six white light-emitting diode (LED), evenly dispersed light throughout the LCD panel. It provides industry-leading matching of less than 1% error due to the accurate monitoring of a single LED current. Its high power efficiency (up to 88%) helps save battery power. And it uses a small outline pin-out chip-scale package (3 mm × 3 mm LFCSP) to save 44% of the printed circuit board (PCB) area with the closest competitor. The ADM8845 monitors the operating current matching of each LED individually for excellent current matching performance by using six separate current control modules (up to 1% maximum matching error). This guarantees a uniform backlight brightness across the entire illuminated area of ​​the LCD display. The two control inputs of the ADM8845 allow LEDs to be switched on and off in two separate modules, 4 LEDs and 2 LEDs, making them suitable for use in the latest clamshell mobile phones, Has a primary display and a smaller secondary display. The brightness of the LEDs can be adjusted by changing the input signal to these control pins. To achieve maximum power efficiency, the on-chip charge pump automatically switches between 1 ×, 1.5 × and 2 × depending on the supply voltage of the battery. The soft-start circuit limits inrush current to prevent sudden voltage changes at startup.