Low-Cost, Internal-Switch, Step-Down Regulator for LCD Displays

The MAX8723 is a high-efficiency, switch-mode, step-down regulator with a 14V internal power switch. With only a few external passive components, this low-cost regulator can generate a fixed 3.3V or adjustable DC output voltage of 2.0V to 3.6V (dual mode) from a 6V to 13.2V DC source. The 13.2V input voltage range makes this part ideal for LCD displays, point-of-load regulators, and other 8/12V-powered industrial equipment applications.

The MAX8723 can deliver up to 2A. It features an internal power MOSFET, a built-in bootstrap diode for its MOSFET driver, and an interface for an external synchronous rectifier MOSFET drive to replace the Schottky diode and improve efficiency. Its fixed-frequency PWM/skip-mode operation and current-mode control architecture provide fast load-transient response without compensation. The switching frequency is a pin-selectable 500kHz, 1MHz, or 1.5MHz, minimizing the size of external components.

The MAX8723 has built-in soft-start, current-limit, thermal-shutdown, and timer-delayed output-fault shutdown functions. The soft-start function limits inrush current during startup, avoiding transients that can trigger the front-end protection circuits and lock up the system. The current limit, thermal-shutdown, and timer-delayed output-fault shutdown functions protect the power supply against fault conditions.

The MAX8723 also includes a linear regulator (VL), which provides a fixed 5V output (25mA) to support small external loads. The reference output is high-precision (2V ±1%) and can also supply small external load currents.

The MAX8723 is available in the 16-pin, 4mm x 4mm, TQFN package.

Applications

* 8/12V Industrial Equipment * Digital System Power Supplies * LCD Monitors * LCD TVs * Point-of-Load Regulators

* 6V to 13.2V input supply range

* Integrated 14V 2A n-channel MOSFET switch

* Preset 1.5% accurate 3.3V fixed-output voltage or 2.0V to 3.6V adjustable output (Dual Mode)

* Current-mode PWM operation

* Frequency-selectable 500kHz/1MHz/1.5MHz

* Internal 5V linear regulator supports up to 25mA external load

* 2V precision reference (1%)

* Integrated bootstrap diode for high-side MOSFET drive

* External synchronous rectifier driver

* Built-in soft-start

* 200µA standby mode

* Timer-delayed output fault protection

* Thermal shutdown protection

* Small 16-pin 4mm x 4mm thin QFN package