Triple Charge-Pump TFT LCD DC-DC Converter

Active: In Production.

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 high-power 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 (V_OUT) 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 (V_POS) and one negative output (V_NEG). These additional outputs use external diode and capacitor multiplier stages (as many stages as required) to regulate output voltages up to +35V and -35V.

The constant switching frequency and a proprietary regulation algorithm minimize output ripple and capacitor sizes for all three charge pumps. The MAX1747 is available in the ultra-thin TSSOP package (1.1mm max height).

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