Complete Bias And White Led Power Supplies For Small Tft Displays Integrated Products

The MAX1578 MAX1579 provide four regulated outputs to meet all the voltage requirements for small active- matrix TFT-LCD Displays in handheld devices where minimum external components and high efficiency are required. Each device consists of three advanced Charge Pumps for LCD bias power and a Step-up con- verter for driving up to 8 series white LEDs for back- lighting. The input voltage range is from 2.7V to 5.5V. The Charge Pumps provide fixed +5V, +15V, and -10V for the LCD bias circuits. No external Diodes are need- ed. A high-efficiency, fractional (1.5x/2x) Charge Pump followed by a low-dropout linear Regulator provides +5V to power the source driver. Automatic mode changing achieves the highest conversion efficiency. Two multi- stage, High-Voltage Charge Pumps generate +15V and -10V to provide VON and VOFF, respectively. Utilizing a unique clocking scheme and internal drivers, these Charge Pumps eliminate parasitic charge-current glitch- es and reduce maximum input current, resulting in low electromagnetic emissions. The outputs are sequenced during startup and shutdown. In shutdown, the outputs are discharged to zero. By Maxim Integrated Products