Cirrus-logic AN375 Manual do Utilizador Página 1

Copyright  Cirrus Logic, Inc. 2013(All Rights Reserved)Cirrus Logic, Inc.http://www.cirrus.comApplication NoteDesign Guide for a CS1615 and CS1616 Si

AN37510 AN375REV4Ideally, reflected voltage VReflected should have nearly the same value as peak line voltage VINPK because operating the transformer

AN375AN375REV4 11allow the RC circuit to respond to the variable dissipation requirements. The RC circuit should be designed to track voltage Vrect.Th

AN37512 AN375REV4Step 6) Calculate Peak CurrentThe switching period TT used in Equation 13 on page 11 is found only at the peak of the minimum input

AN375AN375REV4 13Step 7) Calculate Primary Winding InductancePrimary inductance LP is calculated to allow sufficient current build up at the 90° poin

AN37514 AN375REV4Step 12) Calculate Primary and Secondary CurrentsSince the primary and secondary currents have a variable peak and duty cycle across

AN375AN375REV4 15Step 14) Dimmer Compatibility CircuitResistor R15, FET Q2, and associated bias circuit components constitute the recommended dimmer c

AN37516 AN375REV4The flyback/buck-boost transformer auxiliary winding monitors output overvoltage and the ZCD function. The auxiliary winding turns ra

AN375AN375REV4 17Assume using a BJT with a beta equal to 20, then the maximum collector current Icollector is equal to 300mA. The CLAMP pin is driven

AN37518 AN375REV44 Design ExampleThe Cirrus Logic CRD1615-8W reference design is used for the design example. The required operating parameters for th

AN375AN375REV4 19Reflected voltage VReflected was initially selected to be 170V. To avoid incomplete layers in the transformer winding voltage VReflec

AN3752 AN375REV4Contacting Cirrus Logic SupportFor all product questions and inquiries contact a Cirrus Logic Sales Representative. To find the one ne

AN37520 AN375REV4Using turns ratio N derived in Equation 36 on page 19, calculate minimum reflected voltage VReflected(min) and maximum reflected volt

AN375AN375REV4 21Step 8) Calculate Sense Resistor RSense (R19)Use Equation 16 on page 13 to solve for sense resistance RSense. See Equation 43:Resisto

AN37522 AN375REV4Calculate minimum and maximum period T1 using Equations 50 and 51:Calculate minimum and maximum switching frequencies using Equations

AN375AN375REV4 23Step 16) Zero-current DetectionThe recommended design approach is to set the auxiliary voltage VAUX to 22V. A higher voltage is accep

AN37524 AN375REV45 Appendix5.1 SchematicFigure 8. Schematic=B5(9B&zoll{vmzoll{lunpullykh{lkyh~uGiwhy{GJzoll{[VY\V YWXZjUshtily{ jUsht

AN375AN375REV4 255.2 DimensionsFigure 9. PCB Dimensions

AN37526 AN375REV45.3 Bill of MaterialsItem Rev DescripƟon Qty Reference Designator MFG MFG P/N1 DIODE RECT 200V 0.8A NPB MINIDIP 1 BR1 DIODES INC HD02

AN375AN375REV4 27Revision HistoryRevision Date ChangesREV1 DEC 2012 Initial release.REV2 FEB 2013 Changed content to align with production CRD1615-8W.

AN375AN375REV4 32 IntroductionThis application note is a guide to designing a solid-state lighting (SSL) LED lamp circuit using Cirrus Logic's CS

AN3754 AN375REV42.2 Definition of SymbolsSymbol DescriptionFSWSwitching frequencyTT Switching periodT1 Primary FET ‘ON’ timeT2 Secondary rectifier dio

AN375AN375REV4 53 Design ProcessThe design process for a single-stage power converter system can be partitioned into six circuit blocks (see Figure 1)

AN3756 AN375REV43.1 Operating ParametersTo initiate the design procedure, a set of operating parameters is required. Operating parameters required for

AN375AN375REV4 73.3 Flyback Stage DesignPredict T3 andCalculate Duty CycleCalculate IPKCalculatePrimary InductanceCalculate RSense,RCTRL1, and RCTRL2D

AN3758 AN375REV43.4 Flyback DesignFigure 3 is a composite timing diagram of the primary and secondary winding currents and switching periods. The flyb

AN375AN375REV4 9When operating in Dimmer Mode, the line current must be at least as high as dimmer hold current Ihold. The dimmer hold current is a sy