Texas Instruments UCC2977EVM User manual

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July 2002 PMP Systems Power
User’s Guide
SLLU049

IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications,
enhancements, improvements, and other changes to its products and services at any time and to discontinue
any product or service without notice. Customers should obtain the latest relevant information before placing
ordersandshouldverifythatsuchinformationiscurrentandcomplete.AllproductsaresoldsubjecttoTI’sterms
and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI
deems necessary to support this warranty. Except where mandated by government requirements, testing of all
parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for
their products and applications using TI components. To minimize the risks associated with customer products
and applications, customers should provide adequate design and operating safeguards.
TIdoesnotwarrantorrepresentthatanylicense, eitherexpress orimplied, isgranted underanyTIpatentright,
copyright,maskworkright,orotherTIintellectualpropertyrightrelatingtoanycombination,machine,orprocess
inwhichTIproductsorservicesareused.InformationpublishedbyTIregardingthird–partyproductsorservices
does not constitute a license from TI to use such products or services or a warranty or endorsement thereof.
Use of such information may require a license from a third party under the patents or other intellectual property
of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of information in TI data books or data sheets is permissible only if reproduction is without
alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction
of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for
such altered documentation.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that
product or service voids all express and any implied warranties for the associated TI product or service and
is an unfair and deceptive business practice. TI is not responsible or liable for any such statements.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2002, Texas Instruments Incorporated

EVM IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:
Thisevaluationkit being soldbyTI is intendedforuse for ENGINEERING DEVELOPMENT OR EVALUATION
PURPOSES ONLY and is not considered by TI to be fit for commercial use. As such, the goods being provided
may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective
considerations, including product safety measures typically found in the end product incorporating the goods.
As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic
compatibility and therefore may not meet the technical requirements of the directive.
ShouldthisevaluationkitnotmeetthespecificationsindicatedintheEVMUser’sGuide,thekitmaybe returned
within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE
WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED,
IMPLIED,ORSTATUTORY,INCLUDINGANYWARRANTY OF MERCHANTABILITY ORFITNESSFORANY
PARTICULAR PURPOSE.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user
indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products
receivedmaynotberegulatorycompliant oragency certified (FCC,UL, CE,etc.). Dueto theopen construction
oftheproduct,itistheuser’sresponsibilitytotakeanyandallappropriateprecautionswithregardtoelectrostatic
discharge.
EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE
TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
TI currently deals with a variety of customers for products, and therefore our arrangement with the user is not
exclusive.
TI assumes no liability for applications assistance, customer product design, software performance, or
infringement of patents or services described herein.
Please read the EVM User’s Guide and, specifically, the EVM Warnings and Restrictions notice in the EVM
User’sGuidepriortohandlingtheproduct.Thisnoticecontainsimportantsafetyinformationabouttemperatures
and voltages. For further safety concerns, please contact the TI application engineer.
Persons handling the product must have electronics training and observe good laboratory practice standards.
No license is granted under any patent right or other intellectual property right of TI covering or relating to any
machine, process, or combination in which such TI products or services might be or are used.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2002, Texas Instruments Incorporated

EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the input and output voltage ranges specified in the
user’s guide.
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.
Applyingloadsoutsideofthespecifiedoutputrangemayresultinunintendedoperationand/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.
Duringnormaloperation,somecircuitcomponentsmayhavecasetemperaturesgreaterthan
60°C.TheEVM isdesignedto operateproperlywith certaincomponentsabove 60°C aslong
astheinputandoutput rangesare maintained.Thesecomponentsincludebut arenot limited
tolinearregulators,switchingtransistors,passtransistors,andcurrentsenseresistors.These
typesof devicescanbeidentifiedusingtheEVM schematiclocated intheEVMUser’sGuide.
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 2002, Texas Instruments Incorporated

Related Documentation From Texas Instruments
iii
Preface
Read This First
About This Manual
This users guide describes the characteristics, operation, and use of the
UCC2977 CCFL backlight converter evaluation module (EVM). The users
guide includes a schematic diagram, bill of materials and test results.
How to Use This Manual
This document contains the following chapters:
-Chapter 1—Hardware
-Chapter 2—Design Procedure
-Chapter 3—Test Results
Related Documentation From Texas Instruments
-Texas Instruments Users Manual, UCC3976/7 Users Manual, TI
Literature Number SLUU108
-Texas Instruments Data Sheet, UCC2977, TI Literature Number
SLUS499A
FCC Warning
Thisequipmentisintendedforuseinalaboratorytestenvironmentonly.Itgen-
erates,uses,andcanradiateradiofrequencyenergy,andhasnotbeentested
for compliance with the limits of computing devices pursuant to subpart J of
part 15 of FCC rules, which are designed to provide reasonable protection
against radio frequency interference. Operation of this equipment in other en-
vironmentsmaycauseinterferencewithradiocommunications,inwhichcase
the user at his own expense will be required to take whatever measures may
be required to correct this interference.

iv

Contents
v
Contents
1 Hardware 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Introduction 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Operating Specifications 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Schematic 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Bill of Materials 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Board Layout 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Design Procedure 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Push-Pull Inductor Selection 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Frequency Range Setting 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Analog Dimming of the Lamp 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 Open-Lamp Voltage Programming 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5 Shutdown 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6 No Lock 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.7 Burst Dimming 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.8 Clamp Circuit (Optional) 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Test Results 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Test Setup 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.1 Lighting CCFL 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.2 Analog Dimming Test 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.3 Burst Dimming Test 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Test Results 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents
vi
Figures
1–1 UCC2977EVM Schematic 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–2 Top Silk Screen With Top Copper Layer 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–3 Top Layer Copper 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–4 Bottom Layer Copper 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–1 Test Setup 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–2 Test Setup for Analog Dimming 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–3 Test Setup for Burst Dimming 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–4 Efficiency With a Low Profile Sumida Inductor 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–5 Efficiency With a High Profile Toko Inductor 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–6 Transformer Input/Output Voltages at VI= 3 V 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–7 Transformer Input/Output Voltages at VI= 6 V 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–8 Burst Dimming With 50% Duty Cycle 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–9 Burst Dimming With 80% Duty Cycle 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–10 Open Lamp Protection 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tables
1–1 Operating Specifications 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–2 Bill of Materials Required for the UCC2977 (SLUP178) 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
Hardware
The UCC2977 evaluation module (SLUP178) provides a reference design for
evaluating the performance of a high efficiency CCFL backlight converter
usingthe UCC2977 (push-pull backlightcontroller).Thedevice contains all of
the circuitry necessary to control a backlight converter. This chapter contains
the schematic, board layout, and the bill of materials. The evaluation module
(EVM) performance specifications are also given.
Topic Page
1.1 Introduction 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Operating Specifications 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Schematic 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Bill of Materials 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Board Layout 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1

Introduction
1-2
1.1 Introduction
TheUCC2977EVM(SLUP178)isa1.8-Wdc/acinvertermoduleusedtodrive
a cold cathode fluorescent lamp (CCFL) with a piezoelectric transformer
(PZT). This EVM consists of a push-pull circuit using the UCC2977 controller.
Theprincipleofoperationfortheinverterisexplainedintheapplicationsection
of the UCC2977 data sheet.
1.2 Operating Specifications
This section summarizes the performance specifications of the SLUP178
converter. Table 1–1 lists the operating specifications for the SLUP178.
Table 1–1.Operating Specifications
Input voltage (VIN)3~6 Vdc
Output voltage (Lamp_HV, Lamp LV) 300 Vac, rms
Output current (lamp current) 4.7 mA, rms
Operating frequency (kHz) 100 kHz
Burst dimming (BD )†Square wave, 120 Hz, 0 to 3 V
Analog dimming (AD) 0~3 Vdc
CCFL lamp JKL BF3100–20B (100 mm, 270 VRMS)
†Use a function generator.