LM22677/LM22677Q

December 10, 2010

5A SIMPLE SWITCHER®, Step-Down Voltage Regulator

with Synchronization or Adjustable Switching Frequency

General Description

The LM22677 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 N-channel MOSFET. The series consists of a

fixed 5V output and an adjustable version.

use complete design using a minimum number of external

components

and

National’s

design

tool.

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 LM22677 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.

Features

-ADJ (outputs as low as 1.285V)

-5.0 (output fixed to 5V)

kHz and 1 MHz

Q100 grade 1 qualified (-40°C to +125°C operating

junction temperature)

Package

Applications

Simplified Application Schematic

30074101

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300741

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