LM2679_15 Datasheet, PDF (1/35 Pages) Texas Instruments – LM2679 SIMPLE SWITCHER® 5A Step-Down Voltage Regulator with Adjustable Current

LM2679
www.ti.com
SNVS026N – MARCH 2000 – REVISED APRIL 2013
LM2679 SIMPLE SWITCHER^® 5A Step-Down Voltage Regulator with Adjustable Current
Limit
Check for Samples: LM2679
FEATURES
1
•2 Efficiency Up to 92%
• Simple and Easy to Design with (Using Off-
The-Shelf External Components)
• Resistor Programmable Peak Current Limit
Over a Range of 3A to 7A.
• 120 mΩ DMOS Output Switch
• 3.3V, 5V and 12V Fixed Output and Adjustable
(1.2V to 37V ) Versions
• ±2% Maximum Output Tolerance Over Full
Line and Load Conditions
• Wide Input Voltage Range: 8V to 40V
• 260 KHz Fixed Frequency Internal Oscillator
• Softstart Capability
• −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
DESCRIPTION
The LM2679 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 5A 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 LM2679 are available from several
manufacturers to greatly simplify the design process.
Other features include the ability to reduce the input
surge current at power-ON by adding a softstart
timing capacitor to gradually turn on the regulator.
The LM2679 series also has built in thermal
shutdown and resistor programmable current limit of
the power MOSFET switch to protect the device and
load circuitry under fault conditions. The output
voltage is specified to a ±2% tolerance. The clock
frequency is controlled to within a ±11% tolerance.
Typical Application
Input
Voltage
8V to 40V
C_IN ^{+ + +}
3 x 15 PF/50V
Feedback
0.01 PF
V_IN
0.47 PF
LM2679 - 5.0
Boost
Softstart
5.6k
1 nF
Current
Limit
Adjust
Switch
Ground ^Output
Output
L
Voltage
22 PH
5V/5A
+
+ _COUT
6TQ045S
2 x 180 PF/16V
I_{CL =}
37,125
R_ADJ
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
SIMPLE SWITCHER, Switchers Made Simple are registered trademarks of Texas Instruments.
2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2000–2013, Texas Instruments Incorporated