L6728D datasheet(9/33 Pages) STMICROELECTRONICS

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L6728D

Device description

Doc ID 16498 Rev 1

9/33

Device description

The L6728D is a single-phase PWM controller with embedded high-current drivers which

provides complete control logic and protection features for easy implementation of a general

DC-DC step-down converter. Designed to drive N-channel MOSFETs in a synchronous

buck topology, this 10-pin device provides a high level of integration to allow a reduction in

cost and size of power supply solutions, while also providing real-time PGOOD in a compact

DFN10 3x3 mm package.

The L6728D is designed to operate from a 5 V or 12 V supply. The output voltage can be

precisely regulated to as low as 0.8 V with ±0.8% accuracy over line and temperature

variations. The switching frequency is internally set to 300 kHz.

This device provides a simple control loop with a voltage-mode error amplifier. The error

amplifier features a 15 MHz gain-bandwidth product and 8 V/µs slew rate, allowing high

regulator bandwidth for fast transient response.

To prevent load damage, the L6728D provides protection against overcurrent, overvoltage,

undervoltage and feedback disconnection. The overcurrent trip threshold is programmable

using a resistor connected from Lgate to GND. Output current is monitored across the low-

side MOSFET RDS(on), eliminating the need for expensive and space-consuming sense

resistors. Output voltage is monitored through the dedicated VSEN pin.

The L6728D implements soft-start by increasing the internal reference in closed-loop

regulation. The low side-less feature allows the device to perform soft-start over a pre-

biased output, avoiding high current return through the output inductor and dangerous

negative spike at the load side.

The L6728D is available in a compact DFN10 3x3 mm package with exposed pad.

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