Features: * Efficiency up to 96%
* Available in SO-8, 8-pin DIP and LLP packages
* Computer Design Software LM267X Made Simple (version 6.0)
* Simple and easy to design with
* Requires only 5 external components
* Uses readily available standard inductors
* 3.3V, 5.0V, 12V, and adjustable output versions
* Adjustable version output voltage range: 1.21V to 37V
* ±1.5% max output voltage tolerance over line and load conditions
* Guaranteed 500mA output load current
* 0.25 DMOS Output Switch
* Wide input voltage range: 8V to 40V
* 260 kHz fixed frequency internal oscillator
* TTL shutdown capability, low power standby mode
* Thermal shutdown and current limit protectionApplication*Simple High Efficiency (>90%) Step-Down (Buck) Regulator
*Efficient Pre-Regulator for Linear Regulators
*Positive-to-Negative ConverterPinout
SpecificationsSupply Voltage 45V
ON/OFF Pin Voltage -0.1V VSH 6V
Switch Voltage to Ground -1V
Boost Pin Voltage VSW +8V
Feedback Pin Voltage -0.3V VFB 14V
ESD Susceptibility
Human Body Model (Note 2) 2 kV
Power Dissipation Internally Limited
Storage Temperature Range -65 to +150
Lead Temperature
M Package
Vapor Phase (60s) +215
Infrared (15s) +220
N Package (Soldering, 10s) +260
LLP Package (See AN-1187)
Maximum Junction Temperature +150
DescriptionThe LM2674 series of regulators are monolithic integrated circuits built with a LMDMOS process. These regulators provide all the active functions for a step-down (buck) switching regulator, capable of driving a 500 mAload current with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5.0V, 12V, and an adjustable output version.
Requiringaminimumnumberofexternalcomponents,these regulators are simple to use and include patented internal frequency compensation (Patent Nos. 5,382,918 and 5,514,947) and a fixed frequency oscillator.
The LM2674 series operates at a switching frequency of 260 kHz,thus allowing smaller sized filter components than what would be needed with lower frequency switching regu-lators. Because of its very high efficiency (>90%), the cop-per traces on the printed circuit board are the only heat sinking needed.
A family of standard inductors for use with the LM2674 are available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies using these advanced ICs. Also included in the datasheet are selector guides for diodes and capacitors designed to work in switch-mode power supplies.
Other features include a guaranteed ±1.5% tolerance on output voltage within specified input voltages and output load conditions, and ±10% on the oscillator frequency. Ex-ternal shutdown is included, featuring typically 50 A stand-by current. The output switch includes current limiting,as well as thermal shutdown for full protection under fault conditions.
To simplify the LM2674 buck regulator design procedure there exists computer design software, LM267X Mad Simple (version 6.0).
LM2674 Data Sheet
