MAX1747

19-1788; Rev 0; 10/00 KIT ATION EVALU LE B A IL A AV Triple Charge-Pump TFT LCD DC-DC Converter General Description MAX1747 Features o Adjustable Outputs Up to +5.5V Main High-Power Output Up to +35V Positive Charge-Pump Output Down to -35V Negative Charge-Pump Output o 200kHz to 2MHz Adjustable Switching Frequency o +2.7V to +4.5V Input Supply o Internal Power MOSFETs o 0.1µA Shutdown Current o Internal Soft-Start o Power-Ready Output o Internal Supply Sequencing o Fast Transient Response o Ultra-Thin Solution (No Inductors) o Thin TSSOP Package (1.1mm max) The MAX1747 triple charge-pump DC-DC converter provides the regulated voltages required by active matrix thin-film transistor (TFT) liquid-crystal displays (LCDs) in a low-profile TSSOP package. One highpower and two low-power charge pumps convert the +2.7V to +4.5V input supply voltage into three independent output voltages. The primary high-power charge pump generates an output voltage (VOUT) between 4.5V and 5.5V that is regulated within ±1%. The low-power BiCMOS control circuitry and the low on-resistance (R ON ) power MOSFETs maximize efficiency. The adjustable switching frequency (200kHz to 2MHz) provides fast transient response and allows the use of small low-profile ceramic capacitors. The dual low-power charge pumps independently regulate one positive output (VPOS) and one negative output (VNEG). These additional outputs use external diode and capacitor multiplier stages (as many stages as required) to regul...