Multiple-Output Power-Supply Controllers for LCD Monitors

The MAX1530/MAX1531 multiple-output power-supply controllers generate all the supply rails for thin-film transistor (TFT) liquid-crystal display (LCD) monitors. Both devices include a high-efficiency, fixed-frequency, step-down regulator. The low-cost, all N-channel, synchronous topology enables operation with efficiency as high as 93%. High-frequency operation allows the use of small inductors and capacitors, resulting in a compact solution. The MAX1530 includes three linear regulator controllers and the MAX1531 includes five linear regulator controllers for supplying logic and LCD bias voltages. A programmable startup sequence enables easy control of the regulators.

The MAX1530/MAX1531 include soft-start functions to limit inrush current during startup. An internal step-down converter current-limit function and a versatile overcurrent shutdown protect the power supplies against fault conditions. The MAX1530/MAX1531 use a current-mode control architecture, providing fast load transient response and easy compensation. An internal linear regulator provides MOSFET gate drive and can be used to power small external loads.

The MAX1530/MAX1531 can operate from inputs as high as 28V and are well suited for LCD monitor and TV applications running directly from AC/DC wall adapters. Both devices are available in a small (5mm x 5mm), ultra-thin (0.8mm), 32-pin QFN package and operate over the -40°C to +85°C temperature range.

Applications

* LCD Monitors and TVs

* 4.5V to 28V Input Voltage Range

* 250kHz/500kHz Current-Mode Step-Down Converter

* Small Inductor/Capacitors

* No Sense Resistor

* Three Positive Linear Regulator Controllers

* One Positive and One Negative Additional Controller (MAX1531)

* Small Input and Output Capacitors

* Timed Reset Output

* Uncommitted Overcurrent Protection (MAX1531)

* Soft-Start for All Regulators

* Programmable Input Undervoltage Comparator

* Programmable Startup Sequencing