The MAX8728 generates all the power rails for the thin film transistor (TFT) liquid crystal display (LCD) panel in the TV and monitor. It includes step-down and step-up regulators, positive and negative charge pumps, and dual mode, logic-controlled high-voltage switch control blocks. Operates at 7V to 13.2V input voltages and is optimized for LCD TV panels and LCD applications that operate directly from 12V power.
Simplified Operating Circuit
Boost and step-down regulators feature internal power mosFETs and high-frequency operation that allow the use of small inductors and capacitors, resulting in a compact solution. Both switch regulators use a fixed frequency current mode control architecture to provide fast load transient response and easy compensation.
The positive and negative charge pump regulator provides the TFT gate drive power supply voltage. Both output voltages can be adjusted with an external resistance divider. The MAX8728 is available in a small size (5mm x 5mm), low size (0.8mm), 32-pin TQFN package with an operating temperature range of -40°C to +85°C.
MAX8728 Pin Configuration
Features
● Optimize the 10.8V to 13.2V input power supply
● 7V to 13.2V input power supply range
● Optional frequency (500kHz/1MHz/1.5MHz)
● Current type step-down regulator
- 14V internal N-channel MOSFETs
- 1.5% accurate output
● Current mode boost regulator
- 19V internal n channel MOSFETs
- 1% accurate output
- True Shutdown(output returns to zero)
● 180° phase-out switch
● Adjustable positive/negative charge pump
● All soft start and timer delay fault latches output
● Logic control, high voltage switch
● Power-on and power-off sequence
● Thermal overload protection
Applications
● Liquid crystal Display
● LCD TV
MAX8728 Typical Operating Circuit
MAX8728 Functional Diagram
