The MAX1748/MAX8726 triple-output DC-DC converters in a low-profile TSSOP package provide the regulated voltages required by active-matrix, thin-film transistor (TFT) liquid-crystal displays (LCDs). One high-power DC-DC converter and two low-power charge pumps convert the +3.3V to +5V input supply voltage into three independent output voltages. The primary 1MHz DC-DC converter generates a boosted output voltage (VMAIN) up to 13V using ultra-small inductors and ceramic capacitors. The low-power BiCMOS control circuitry and the low on-resistance (0.35Ω) of the integrated power MOSFET allows efficiency up to 93%. 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. For both the MAX17482GTL+ and MAX8726, the supply sequence is VMAIN first, VNEG next, and finally VPOS. The MAX17482GTL+ soft-starts each supply as soon as the previous supply finishes. The MAX8726 adds a delay between the startups of VMAIN and VNEG and also between VNEG and VPOS. The MAX1748/MAX8726 are available in the ultra-thin TSSOP package (1.1mm max height).
Feature
- Three Integrated DC-DC Converters
- 1MHz Current-Mode PWM Boost Regulator
- Up to +13V Main High-Power Output
- ±1% Accuracy
- High Efficiency (93%)
- 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
- 0.6mA Quiescent Current
- Internal Soft-Start
- Power-Ready Output
- Ultra-Small External Components
- Thin TSSOP Package (1.1mm max)
Applications
- Camcorders
- Digital Still Cameras
- Passive-Matrix LCD Displays
- PDAs
- TFT Active-Matrix LCD Displays
