Texas Instruments UCC28517 User Manual

UCC28517 EVM

User’s Guide

User’ s Gu ide

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DYNAMIC WARNINGS AND RESTRICTIONS

It is important to operate this EVM within the maximum input voltage ranges specified in Section 6.
Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM.

If there are questions concerning the input range, please contact a TI field representative prior to connecting
the input power.

Applying loads outside of the specified output range may result in unintended operation and/or possible
permanent damage to the EVM. Please consult the EVM User’s Guide prior to connecting any load to the EVM
output. If there is uncertainty as to the load specification, please contact a TI field representative.

During normal operation, some circuit components may have case temperatures greater than 50°C. The EVM
is designed to operate properly with certain components above 50°C as long as the input and output ranges are
maintained. These components include but are not limited to linear regulators, switching transistors, pass
transistors, and current sense resistors. These types of devices can be identified using the EVM schematic
located in the EVM User’s Guide. When placing measurement probes near these devices during operation,
please be aware that these devices may be very warm to the touch.

Mailing Address:

Texas Instruments
Post Office Box 655303
Dallas, Texas 75265

Copyright  2003, Texas Instruments Incorporated

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SLUU117C − September 2002 − Revised July 2003

UCC28517 EVM

Michael O’Loughlin Power Supply Control Products

Contents

1 Introduction 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 Caution 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 Schematic 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 List of Materials 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 Reference Design Layout 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6 Electrical Characteristics 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7 Reference Design Performance 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 Introduction

The UCC28517 module is a 100-W offline ac-to-dc voltage converter with power factor correction (PFC). The
prototype was designed to show how the UCC28517 could be configured to control two dc-regulated outputs
offline with one control integrated circuit. The module was design to operate over a universal input range of 85
V to 265 V with two dc regulated outputs. Output B is a 12-V, 8-W regulated output intended to be used as a
bias supply and output A is a 385-V, 100-W regulated output.

For this module to function correctly output B needs a minimum load of 4 W and boost capacitor C3 needs to
be completely discharged before applying power. The input needs a minimum of 85 V
voltage is brought up slowly with the use of an ac source or a variable transformer the bootstrap circuitry will
not function correctly. If this procedure is not followed the reference design will not regulate properly.

at power up. If the input

AC

2 Caution

High-voltage levels are present on the evaluation module whenever it is energized. Proper precautions must
be taken when working with the module. Output A has a large energy storage capacitor and must be completely
discharged before the module can be handled. Serious injury can occur if proper safety precautions are not
followed.

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UCC28517 EVM