LM22680/LM22680Q
January 24, 2011
2A SIMPLE SWITCHER, Step-Down Voltage Regulator
with Features
General Description
The LM22680 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 2A
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 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 LM22680 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 A quiescent current
standby condition. An adjustable soft-start feature is provided
by selecting an appropriate external soft-start capacitor.
Features
■ Wide input voltage range: 4.5V to 42V
■ Internally compensated voltage mode control
■ Stable with low ESR ceramic capacitors
■ 200 m N-channel MOSFET
■ Output voltage option:
-ADJ (outputs as low as 1.285V)
■ ±1.5% feedback reference accuracy
■ Switching frequency of 500 kHz, adjustable between
200 kHz and 1 MHz
■ -40°C to 125°C operating junction temperature range
■ Precision enable pin
■ Integrated boot diode
■ Adjustable soft-start
■ Fully WEBENCH enabled
■ Step-down and inverting buck-boost applications
■ LM22680Q is an Automotive Grade product that is AEC-
Q100 grade 1 qualified (-40°C to +125°C operating
junction temperature)
Package
■ PSOP-8 (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
30080701
2011 National Semiconductor Corporation
300807
www.national.com
LM22680/LM22680Q
2A
SIMPLE
SWITCHER,
Step-Down
Voltage
Regulator
with
Features