NATIONAL SEMICONDUCTOR LM22679 User's Manual
Summary
Ideal for powers-intensive systems requiring efficient, stable voltage regulation. This advanced step-down buck converter provides operation across a wide input range (4.5V to 42V) with adjustable soft-start and current limiting features. The manual details the regulator's integrated design, utilizing internal compensation for high efficiency (>90%) across challenging loads. It is designed for demanding professional applications, including Industrial Control, Telecom/Datacom Systems, and Automotive Telematics.
Page 1 Text Content
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November 21, 2008
LM22679 5A SIMPLE SWITCHER®, Step-Down Voltage Regulator with Adjustable Soft-Start and Current Limit General Description Features The LM22679 series of regulators are monolithic integrated Wide input voltage range: 4.5V to 42V circuits which provide all of the active functions for a step-
Internally compensated voltage mode control
down (buck) switching regulator capable of driving up to 5A
Stable with low ESR ceramic capacitors
loads with excellent line and load regulation characteristics.
100 mΩ N-channel MOSFET
High efficiency (>90%) is obtained through the use of a low
ON-resistance N-channel MOSFET. The series consists of a Output voltage options: fixed 5V output and an adjustable version. -ADJ (outputs as low as 1.285V) -5.0 (output fixed to 5V)
The SIMPLE SWITCHER® concept provides for an easy to
use complete design using a minimum number of external ±1.5% feedback reference accuracy
components and National’s WEBENCH® design tool. Switching frequency of 500k Hz National’s WEBENCH® tool includes features such as exter-
-40°C to 125°C operating junction temperature range
nal component calculation, electrical simulation, thermal sim-
Adjustable soft-start
ulation, and Build-It boards for easy design-in. The switching
Adjustable current limit
clock frequency is provided by an internal fixed frequency os-
cillator which operates at 500 k Hz. The LM22679 series also Integrated boot diode
has built in thermal shutdown and current limiting. The current Fully WEBENCH® enabled limit threshold can be adjusted using an external resistor. An
Step-down and inverting buck-boost applications
adjustable soft-start feature is provided by selecting an ap- propriate external soft-start capacitor.
Package TO-263 THIN (Exposed Pad)
Applications Industrial Control Telecom and Datacom Systems Embedded Systems Automotive Telematics and Body Electronics Conversions from Standard 24V, 12V and 5V Input Rails
Simplified Application Schematic
© 2008 National Semiconductor Corporation www.national.com
Page Summary Contents For NATIONAL SEMICONDUCTOR LM22679 User's Manual
Manual Details
| Brand | National |
|---|---|
| Pages | 14 |
| File Size | 350.11 KB |
| Published | July 22, 2026 |
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Frequently Asked Questions
What is the operating input voltage range for this regulator?
The VIN source input voltage operates from 4.5V to 42V.
How can I adjust the current limit?
Attach an external resistor between pin 5 (IADJ) and GND. This sets the current limit threshold.
What is the maximum junction temperature?
The operating junction temperature range is -40°C to +125°C.
Does it have a fixed soft-start or adjustable one?
It features an adjustable soft-start, which requires selecting an appropriate external capacitor (pin 7).
What type of design applications is this suited for?
The LM22679 series is suitable for Industrial Control, Telecom and Datacom Systems, Embedded Systems, and Automotive Telematics.