December 18, 2009
LM22672
1A SIMPLE SWITCHER®, Step-Down Voltage Regulator
with Features
General Description
Features
The LM22672 series of regulators are monolithic integrated
circuits which provide all of the active functions for a step-
down (buck) switching regulator capable of driving up to 1A
loads with excellent line and load regulation characteristics.
High efficiency (>90%) is obtained through the use of a low
ON-resistance N-channel MOSFET. The series consists of a
fixed 5V output and an adjustable version.
Wide input voltage range: 4.5V to 42V
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Internally compensated voltage mode control
Stable with low ESR ceramic capacitors
200 mΩ N-channel MOSFET
Output voltage options:
-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
components and National’s WEBENCH® design tool.
National’s WEBENCH® tool includes features such as exter-
nal component calculation, electrical simulation, thermal sim-
ulation, and Build-It boards for easy design-in. The switching
clock frequency is provided by an internal fixed frequency os-
cillator which operates at 500 kHz. The switching frequency
can also be adjusted with an external resistor or synchronized
to an external clock up to 1MHz. It is also possible to self-
synchronize multiple regulators to share the same switching
frequency. The LM22672 series also has built in thermal shut-
down, current limiting and an enable control input that can
power down the regulator to a low 25 µA quiescent current
standby condition. An adjustable soft-start feature is provided
by selecting an appropriate external soft-start capacitor.
±1.5% feedback reference accuracy
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Switching frequency of 500 kHz, adjustable between 200
kHz and 1 MHz
-40°C to 125°C operating junction temperature range
Precision enable pin
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Integrated boot diode
Adjustable soft-start
Fully WEBENCH® enabled
Step-down and inverting buck-boost applications
Package
PSOP-8 (Exposed Pad)
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Applications
Industrial Control
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Telecom and Datacom Systems
Embedded Systems
Automotive Telematics and Body Electronics
Conversions from Standard 24V, 12V and 5V Input Rails
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Simplified Application Schematic
30076701
© 2009 National Semiconductor Corporation
300767
www.national.com