Features

• Constant 200kHz Switching Frequency
• 1.21V Reference Voltage
• Fixed 5V Output Option
• Easily Synchronizable
• Uses All Surface Mount Components
• Inductor Size Reduced to 15µH
• Saturating Switch Design: 0.2 Ohms
• Effective Supply Current: 1.16mA
• Shutdown Current: 20µA
• Cycle-by-Cycle Current Limiting
• Fused Lead SO-8 Package

Typical Application

Description

The LT1576 is a 200kHz monolithic buck mode switching regulator. A 1.5A switch is included on the die along with all the necessary oscillator, control and logic circuitry. The topology is current mode for fast transient response and good loop stability. The LT1576 is a modified version of the industry standard LT1376 optimized for noise sensitive applications.In addition, the reference voltage has been lowered to allow the device to produce output voltages down to 1.2V. Quiescent current has been reduced by a factor of two. Switch on resistance has been reduced by 30%. Switch transition times have been slowed to reduce EMI generation. The oscillator frequency has been reduced to 200kHz to maintain high efficiency over a wide output current range. The pinout has been changed to improve PC layout by allowing the high current high frequency switching circuitry to be easily isolated from low current noise sensitive control circuitry. The new SO-8 package includes a fused ground lead which significantly reduces the thermal resistance of the device to extend the ambient operating temperature range. There is an optional function of shutdown or synchronization. Standard surface mount external parts can be used including the inductor and capacitors.