Description

The LX1681/1682 are monolithic, pulse-width modulator controller ICs that are designed to implement a flexible, low-cost buck (step-down) regulator supply with minimal external components. The LX1681 is a non-synchronous controller, while the LX1682 has a synchronous driver for higher efficiency. The output voltage is adjustable by means of a resistor divider to set the voltage between 1.25V and 4.5V.

Specifications and Features

• Fixed 200kHz Switching Frequency
• Constant Frequency Voltage-Mode Control Requires NO External Compensation
• Hiccup-Mode Over-Current Protection
• High Efficiency
• Output Voltage Set By Resistor Divider
• Under-voltage Lockout
• Soft-Start And Enable
• Synchronous Rectification (LX1682)
• Non-Synchronous Rectification (LX1681)
• Small, 8-pin Surface Mount Package

Application Scenarios

The LX1681/1682 are ideal for the following applications:

• 5V to 3.3V Or Less Buck Regulators
• FPGA Supplies
• Microprocessor Chipset Supplies (e.g. Camino, Whitney, etc.)
• Rambus© RIMM™ Supplies
• Hard Disk Drives
• Computer Add-on Cards

Comparison

• Flexible and low cost
• High efficiency synchronous driver (LX1682) for better performance
• Easy to adjust output voltage with resistor divider
• Compact 8-pin surface mount package

• Fixed 200kHz switching frequency might not be suitable for some applications
• Output voltage range is limited between 1.25V and 4.5V