LM2677T-5.0 National Semiconductor, LM2677T-5.0 Datasheet
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LM2677T-5.0
Manufacturer Part Number
LM2677T-5.0
Description
SIMPLE SWITCHER High Efficiency 5A Step-Down Voltage Regulator with Sync
Manufacturer
National Semiconductor
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© 2000 National Semiconductor Corporation
LM2677
SIMPLE SWITCHER
Voltage Regulator with Sync
General Description
The LM2677 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 characteris-
tics. High efficiency (
low ON-resistance DMOS power switch. The series consists
of fixed output voltages of 3.3V, 5V and 12V and an adjust-
able output version.
The SIMPLE SWITCHER concept provides for a complete
design using a minimum number of external components.
The switching clock frequency can be provided by an inter-
nal fixed frequency oscillator (260KHz) or from an externally
provided clock in the range of 280KHz to 400Khz which al-
lows the use of physically smaller sized components. A fam-
ily of standard inductors for use with the LM2677 are avail-
able from several manufacturers to greatly simplify the
design process. The external Sync clock provides direct and
precise control of the output ripple frequency for consistent
filtering or frequency spectrum positioning.
The LM2677 series also has built in thermal shutdown, cur-
rent limiting and an ON/OFF control input that can power
down the regulator to a low 50µA quiescent current standby
condition. The output voltage is guaranteed to a
ance.
Typical Application
SIMPLE SWITCHER
®
is a registered trademark of National Semiconductor Corporation.
>
90%) is obtained through the use of a
DS101301
®
High Efficiency 5A Step-Down
±
2% toler-
Features
n Efficiency up to 92%
n Simple and easy to design with (using off-the-shelf
n 100 m
n 3.3V, 5V and 12V fixed output and adjustable (1.2V to
n 50µA standby current when switched OFF
n
n Wide input voltage range: 8V to 40V
n External Sync clock capability (280KHz to 400KHz)
n 260 KHz fixed frequency internal oscillator
n −40 to +125˚C operating junction temperature range
Applications
n Simple to design, high efficiency (
n Efficient system pre-regulator for linear voltage
n Battery chargers
n Communications and radio equipment regulator with
external components)
37V ) versions
conditions
switching regulators
regulators
synchronized clock frequency
±
2%maximum output tolerance over full line and load
DMOS output switch
>
DS101301-3
90%) step-down
www.national.com
April 2000