General Description

The MAX1779 triple-output DC-DC converter provides highly efficient regulated voltages required by small active matrix, thin-film transistor (TFT) liquid-crystal displays (LCDs). One high-power DC-DC converter and two low-power charge pumps convert the +2.7V to +5.5V input supply voltage into three independent output voltages.

The primary high-power DC-DC converter generates a boosted output voltage (VMAIN) up to 13V that is regulated within ±1. The low-power BiCMOS control circuitry and the low on-resistance (1Ω) of the integrated power MOSFET allows efficiency up to 91. The 250kHz current-mode pulse-width modulation (PWM) architecture provides fast transient response and allows the use of ultra-small inductors and ceramic capacitors.

The dual charge pumps independently regulate one positive output (VPOS) and one negative output (VNEG). These low-power outputs use external diode and capacitor stages (as many stages as required) to regulate output voltages up to +40V and down to -40V. A proprietary regulation algorithm minimizes output ripple, as well as capacitor sizes for both charge pumps.

The MAX1779 is available in the ultra-thin TSSOP package (1.1mm max height).

Features

♦ Three Integrated DC-DC Converters

♦ 250kHz Current-Mode PWM Boost Regulator

Up to +13V Main High-Power Output

±1 Accuracy

High Efficiency (91)

♦ Dual Charge-Pump Outputs

Up to +40V Positive Charge-Pump Output

Down to -40V Negative Charge-Pump Output

♦ Internal Supply Sequencing

♦ Internal Power MOSFETs

♦ +2.7V to +5.5V Input Supply

♦ 0.1µA Shutdown Current

♦ 0.5mA Quiescent Current

♦ Internal Soft-Start

♦ Power-Ready Output

♦ Ultra-Small External Components

♦ Thin TSSOP Package (1.1mm max)

Applications

TFT Active-Matrix LCD Displays

Passive-Matrix LCD Displays

PDAs

Digital-Still Cameras

Camcorders