LM2676S-ADJ Programmable IC Chips SIMPLE SWITCHER 3A Step Down Voltage Regulator

General Description

The LM2676 series of regulators are monolithic integrated circuits which provide all of the active functions for a stepdown (buck) switching regulator capable of driving up to 3A loads with excellent line and load regulation characteristics. High efficiency (>90%) is obtained through the use of a low ON-resistance DMOS power switch. The series consists of fixed output voltages of 3.3V, 5V and 12V and an adjustable output version.

The SIMPLE SWITCHER concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260KHz) allows the use of physically smaller sized components. A family of standard inductors for use with the LM2676 are available from several manufacturers to greatly simplify the design process.

The LM2676 series also has built in thermal shutdown, current limiting and an ON/OFF control input that can power down the regulator to a low 50µA quiescent current standby condition. The output voltage is guaranteed to a ±2% tolerance. The clock frequency is controlled to within a ±11% tolerance.

Features

• Efficiency up to 94%
• Simple and easy to design with (using off-the-shelf external components)
• 150 mΩ DMOS output switch
• 3.3V, 5V and 12V fixed output and adjustable (1.2V to 37V ) versions
• 50µA standby current when switched OFF
• ±2%maximum output tolerance over full line and load conditions
• Wide input voltage range: 8V to 40V
• 260 KHz fixed frequency internal oscillator
• −40 to +125˚C operating junction temperature range

Applications

• Simple to design, high efficiency (>90%) step-down switching regulators
• Efficient system pre-regulator for linear voltage regulators
• Battery chargers

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Input Supply Voltage 45V

ON/OFF Pin Voltage −0.1V to 6V

Switch Voltage to Ground −1V to V_IN

Boost Pin Voltage V_SW + 8V

Feedback Pin Voltage −0.3V to 14V

Power Dissipation Internally Limited

ESD (Note 2) 2 kV

Storage Temperature Range −65˚C to 150˚C

Soldering Temperature

Wave 4 sec, 260˚C

Infrared 10 sec, 240˚C

Vapor Phase 75 sec, 219˚C

Operating Ratings

Supply Voltage 8V to 40V

Junction Temperature Range (TJ) −40˚C to 125˚C

Typical Application

Connection Diagrams and Ordering Information

TO-263 Package Top View TO-220 Package Top View