Cirrus-logic AN374 Manual do Utilizador

Copyright  Cirrus Logic, Inc. 2013(All Rights Reserved)Cirrus Logic, Inc.http://www.cirrus.comApplication NoteConsiderations for Light Engine Selecti

AN37410 AN374REV2Step 1) LED string configurationDetermine if a series configuration or a parallel configuration is a viable solution for the identifi

AN374AN374REV2 11Bit STRING in register Config3 at address 7 selects the second stage output channel configuration. When bit STRING is set to ‘1’ a se

AN37412 AN374REV2Flyback topology is enabled by setting bit S2CONFIG to ‘1’ in register Config12 at address 44. A flyback topology is selected as a de

AN374AN374REV2 13Figure 5 illustrates the process used to select the second stage flyback mode using the CS1630/31 system design utility.The CS1630/31

AN37414 AN374REV2In Mode 2 the phase synchronizer MOSFET is turned ‘ON’ and the output power PMODE2 is:2. In the parallel configuration, the voltages

AN374AN374REV2 15Figure 6 illustrates the current comparison through the inductor. In this case, the buck is chosen to explainthe point. The same logi

AN37416 AN374REV2The following are disclaimers for this analysis: a. This analysis works better for a non-isolated design. For isolated flyback design

AN374AN374REV2 174.3 Synchronizer Design ConsiderationsThe synchronizer circuit drives an external MOSFET, which may be ground referenced depending on

AN37418 AN374REV25 Design FlowchartFigure 8 shows the flowchart for eliminating incompatible light engines. YesNoYesNoYesNoPick a light enginecandidat

AN374AN374REV2 19Figure 9 shows a way for selecting the correct second stage string configuration.YesNoYesNoYesNoProvide completed lightengine design

AN3742 AN374REV2Contacting Cirrus Logic SupportFor all product questions and inquiries contact a Cirrus Logic Sales Representative. To find the one ne

AN37420 AN374REV2Figure 10 shows a method for selecting the correct power train topology.NoYesNoStartFlybackFlybackBuckIsolationrequired?RequiredVMODE

AN374AN374REV2 216 Data Improvements for the Curve Fitting ProcessThe curve-fitting process consists of translating a typical LED system specification

AN37422 AN374REV2Step 2) Translate into LED current profile at room temperatureThe translation is as shown in Figure 13.Variables K1 and K2 represent

AN374AN374REV2 23Note that any variation of the white string should be compensated for by changing the currents in the other string so that the correc

AN37424 AN374REV26.3.3 Experiment and ApproximationIn many cases, collecting data at room ambient is not difficult. However, getting data across vario

AN374AN374REV2 256.4 Improving Data for Feeding the Curve FitterThis section demonstrates the use of a spreadsheet to manipulate the data collected in

AN37426 AN374REV2If resistance is measured, then The data below shows the white/blue currents across the dim. The format in Figure 18 is useful becaus

AN374AN374REV2 276.4.2 Manipulating Data for Better Curve FitAs mentioned previously, the curve fitter looks for a polynomial fit with a maximum of fo

AN37428 AN374REV2When re-mapping the dim axis, remember the following points:• The dim axis needs to be remapped to the white current and the red curr

AN374AN374REV2 29previous sections. If some of the points in the middle region of the dimming curve are removed, then the fit can be significantly imp

AN374AN374REV2 3TABLE OF CONTENTS1 OVERVIEW OF THE CS1630 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

AN37430 AN374REV27 Performing Curve Fitting7.1 Using the CS1630/31 Application Software to Perform Curve FitThe CS1630/31 application software and gra

AN374AN374REV2 31Once the data has been entered, the curve fitter can be understood by performing the following steps:Step 1) White Gain settingThe en

AN37432 AN374REV2Step 2) Red Gain settingThe entry procedure that is required to preform a curve fit for the Color Gain polynomial is detailed in Fig

AN374AN374REV2 33Step 3) NTC settingIn Figure 29, the value can be entered as an NTC parameter, which corresponds to temperature or in resistances th

AN37434 AN374REV2• Registers CH1CUR and CH2CUR: Channel 1 Reference targets should be the current at 100% brightness on the white string. Channel 2 re

AN374AN374REV2 358 Revision HistoryRevision Date ChangesREV1 NOV 2012 Initial release.REV2 FEB 2013 Corrected typographical errors.

AN3744 AN374REV22 Introduction This application note provides a guide to designing a solid-state lighting (SSL) LED lamp circuit using Cirrus Logic&ap

AN374AN374REV2 52.2 Definition of SymbolsSymbol DescriptionFswSecond-stage switching frequencyFsw1 & Fsw2Switching frequency for channel 1 and cha

AN3746 AN374REV23 Introduction to the Color SystemThe CS1630/31 is a two-channel TRIAC dimmable LED driver IC designed to change the color temperature

AN374AN374REV2 74 Light Engine ChoicesThis section examines key design considerations for a complete lamp design using the CS1630/31 two-channel TRIAC

AN3748 AN374REV2IRed, NTC, and dim variables, the curve fitter will have to compute gains across a larger number of points,which creates the risk of i

AN374AN374REV2 9Constraint 3: Ratio of peak currents between the two channels must be less than 4The DAC reference on the current sense comparator has