General Description

The APW7057 is a 300kHz constant frequency voltage mode synchronous switching controller that drives external N-channel MOSFETs. When the input supply drops close to output, the upper MOSFET remains on, achieving 100 duty cycle. Internal loop compensation is optimized for fast transient response, eliminating external compensation network. The precision 0.8V reference makes this part suitable for a wide variety of low voltage applications. Soft start is internally set to 2ms, limiting the input in-rush current and preventing the output from overshoot during powering up.

Features

• Operates from +5V Input

• 0.8V Internal Reference Voltage

- ±1.5 Accuracy Over Line, Load and Temp.

• 0.8V to VCC Output Range

• Full Duty Cycle Range

- 0 to 100

• Internal Loop Compensation

• Internal Soft Start

- Typical 2ms

• Programmable Over-Current Protection

- Lossless Sensing Using MOSFET RDS (ON)

• Under-Voltage Protection

• Drives External N-Channel MOSFETs

• Shutdown Control

• Small SOP-8 Package

Applications

• Motherboard

• Graphics Cards

• Cable or DSL Modems, Set Top Boxes

• DSP Supplies

• Memory Supplies

• 5V Input DC-DC Regulators

• Distributed Power Supplies