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TC2574

0.5A Step-Down Switching Regulator

TC2574-1 1/6/00

0.5A Step-Down Switching Regulator

GENERAL DESCRIPTION

The TC2574 series of regulators are monolithic inte-

grated circuits ideally suited for easy and convenient design

of a step-down switching regulator (buck converter). All

circuits of this series are capable of driving a 0.5A load with

excellent line and load regulation. These devices are avail-

able in fixed output voltages of 3.3V, 5.0V, 12V and

an adjustable output version.

These regulators were designed to minimize the num-

ber of external components to simplify the power supply

design. Standard series of inductors optimized for use with

the TC2574 are offered by several different inductor manu-

facturers.

Since the TC2574 converter is a switch–mode power

supply, its efficiency is significantly higher in comparison

with popular three-terminal linear regulators, especially with

higher input voltages. In most cases, the power dissipated

by the TC2574 regulator is so low, that the copper traces on

the printed circuit board are normally the only heatsink

needed and no additional heatsinking is required.

The TC2574 features include a guaranteed

±4% toler-

ance on output voltage within specified input voltages and

output load conditions, and

±10% on the oscillator frequency

(

±2% over 0°C to +125°C). External shutdown is included,

featuring 60

µA (typical) standby current. The output switch

includes cycle–by–cycle current limiting, as well as thermal

shutdown for full protection under fault conditions.

FEATURES

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3.3V, 5.0V, 12V and Adjustable Output Versions

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Adjustable Version Output Voltage Range,

1.23 to 37 V

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Guaranteed 0.5 A Output Current

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Wide Input Voltage Range: 4.75 to 40V

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Requires Only 4 External Components

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52kHz Fixed Frequency Internal Oscillator

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TTL Shutdown Capability, Low Power Standby Mode

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High Efficiency

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Uses Readily Available Standard Inductors

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Thermal Shutdown and Current Limit Protection

APPLICATIONS

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Simple and High–Efficiency Step–Down (Buck)

Regulator

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Efficient Pre-Regulator for Linear Regulators

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On–Card Switching Regulators

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Positive to Negative Converters (Buck–Boost)

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Negative Step-Up Converters

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Power Supply for Battery Chargers

ORDERING INFORMATION

Part

Temperature

Number

Package

Range

TC2574-3.3VPA

8-Pin PDIP (Narrow) –40 to +125

°C

TC2574-5.0VPA

8-Pin PDIP (Narrow) –40 to +125

°C

TC2574-12.0VPA

8-Pin PDIP (Narrow) –40 to +125

°C

TC2574-VPA*

8-Pin PDIP (Narrow) –40 to +125

°C

TC2574-VOE*

16-Pin SOIC (Wide)

–40 to +125

°C

TC2574

TelCom Semiconductor reserves the right to make changes in the circuitry and specifications of its devices.

PIN CONFIGURATIONS

1

2

3

4

16

15

14

13

SIG GND

5

6

7

12

11

10

9

8

FB

NC

NC

OUTPUT

TC2574

NC

NC

NC

NC

NC

NC

NC

NC

PWR GND

ON/OFF

1

8

2

7

3

6

4

5

SIG GND

FB

OUTPUT

VIN

VIN

NC

NC

PWR GND

TC2574

ON/OFF

16-Pin SOIC (Wide)

8-Pin PDIP (Narrow)

Note: *ADJ = 1.23 To 37V.