−

+

Q

S

1.25-V

Reference

Regulator

R

Oscillator

Q2

Q1

Switch

Collector

4

Switch

Emitter

Timing

Capacitor

GND

3

2

1

8

7

6

5

Comparator

Inverting Input

Sense

Drive

Collector

100 W

MC33063A, MC34063A

www.ti.com

SLLS636N – DECEMBER 2004 – REVISED JANUARY 2015

8 Detailed Description

8.1 Overview

The MC33063A and MC34063A devices are easy-to-use ICs containing all the primary circuitry needed for

building simple DC-DC converters. These devices primarily consist of an internal temperature-compensated

reference, a comparator, an oscillator, a PWM controller with active current limiting, a driver, and a high-current

output switch. Thus, the devices require minimal external components to build converters in the boost, buck, and

inverting topologies.

The MC33063A device is characterized for operation from –40°C to 85°C, while the MC34063A device is

characterized for operation from 0°C to 70°C.

8.2 Functional Block Diagram

8.3 Feature Description

•

Wide Input Voltage Range: 3 V to 40 V

•

High Output Switch Current: Up to 1.5 A

•

Adjustable Output Voltage

•

Oscillator Frequency Up to 100 kHz

•

Precision Internal Reference: 2%

•

Short-Circuit Current Limiting

•

Low Standby Current

8.4 Device Functional Modes

8.4.1 Standard operation

Based on the application, the device can be configured in multiple different topologies. See the Application and

Implementation section for how to configure the device in several different operating modes.

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Product Folder Links: MC33063A MC34063A