TI 电容隔离技术详解

1、Capacitive IsolationA Technical Overview TemperatureThe RealWorldPressurePositionSpeedFlowHumiditySoundLightISOLATIONPLCm mCDSPDIGITAL INTELLIGENCEADCTRANSCEIVERSRS-485/ CANSignal IsolationWhat is Isolation?Galvanic isolation: Although Circuit 1 and Circuit 2 exchange signals, no current (electrons)

2、 pass from Circuit 1 to Circuit 2.Why is isolation required in electrical systems: Break ground loops Reduce common mode noise Safety from high voltages Circuit 1Circuit 2SignalsVoltage supply 1Voltage supply 2Ground 1Ground 2Why Isolation?Ground Loops More than one conductive path between two circu

3、its creates a ground-loop Multiple ground paths may lead to unintended equalization currentsGround loop can be broken by Disconnecting the grounds Common-mode chokes Frequency selective grounding Differential amplifiers Galvanic isolatorsOnly galvanic isolation provides protection for very large pot

4、ential differencesWhy Isolation?Common Mode NoiseSignals referencedto GND1Signals referencedto GND2Basic/Functional Isolationvs. Reinforced Isolation“An improved basic insulation with such mechanical and electrical properties that, in itself, the insulation provides the same degree of protection aga

5、inst electrical shock as double insulation. It may consist of one or more layers of insulation material.” UL-60950-1Basic/Functional Isolationvs. Reinforced Isolation (contd)When is Reinforced required:- 6kVpp systems (e.g. 600V IGBTs/FETs)- Today: all Medical applications (5kVrms!) - Future: Medica

6、l applications for isolation from the patientNote: this is not complete and subject to change. Exceptions may apply!Applications utilizing IsolationPrimary Task:Isolation between High-Power and Control SignalsIsolation of Bus-Nodes to prevent Corruption of the complete Bus & Common Mode Rejectio

7、nIndustrial: Robotics PLC input/output isolation Industrial networks Motor control Power suppliesApplications utilizing IsolationCommunications: PBX (Private Branch Exchange) and central office Telephone terminal equipment Telephone switching equipment Modems ISDN Ethernet / PoEMedical: Microwave th

8、erapy Patient monitoring Electrocardiographs DefibrillatorsPrimary Task:Medical:Isolation between Power and PatientCommunications:Isolation between Power and CallerIsolation of Bus-Nodes to prevent Corruption of the complete BusConsumer Electronics: Video (TV, VCR, etc.) Plasma displays Electronic g

9、aming Home appliancesApplications utilizing IsolationComputers & Office Equipment Isolated I/O Printers and plotters Fax machinesPrimary Task:Isolation between High-Power and UserNomenclatures / Definitions (1/3) Operation Voltage:Voltage that may be applied continuously across the Isolation bar

10、rier, mostly 560Vpk or 890Vpk Transient Voltage:Voltage that may occur temporarily across the barrier (tested per VDE for 1 minute), mostly 4kVpk (relates to 3kVrms per UL, as tested for 10s only) or 6kVpk Surge VoltageSingle event surge, with the assumption that all effects have been recovered from

11、 prior to another surge-event, mostly rated for a 10kV single peak.Nomenclatures / Definitions (2/3) Basic / Functional Isolation:Assumes a single level of isolation with a certain strength. Applicable for most applications in industrial for fieldbusses and AC-equipment up to 400Vrms, and for consum

12、er electronics. Mostly rated at 560Vpk continuous, 4kVpk transient voltage. Reinforced / Double Isolation:Double Isolation assumes a two-level isolation with a certain strength each. Reinforced addresses a single level of isolation that, however, provides the same reliability as the two-layer. Appli

13、cable for most medical applications and AC-equipment above 400Vrms. Mostly rated at 890Vpk continuous, 6kVpk transient , 10kV surge voltage. Medical needs 5kVrms transient.Intrinsically safe Applications demand double isolation.Note: the End-equipment-standard (e.g. IEC-60950 for communications or I

14、EC-60601-1 for medical) dictates what is needed on silicon levelNomenclatures / Definitions (3/3) Common Mode Transient Suppression:Discusses the quick change in Reference potential primary to secondary. Its given as the dU/dt up to which no false toggeling of the output will occur (e.g. 35kV/us). U

15、sually scales linearly with Vcc. Creepage and ClearanceDiscusses the surface-distance that may conduct if wet/polluted, respectively the air-distance. For 560V/4kV mostly 4mm is sufficient, for 890V/6kV mostly 8mm is needed. Depends on pollution degree5 Questions to allow educated solution-proposals

16、1.Isolation strength: basic/reinforced?2.Isolation voltage: 4kVpeak, 560Vpeak continuos / 6kVpeak, 890V peak continous?3.Stand-alone isolation or integration (Transceiver, Gate-Driver, Data-Converter)?4.Supply Voltages?5.Channel-count?New Generation Capacitive IsolationHigh voltage capacitor Isolato

17、r constructionTop plate = CuBottom Plate = Silicon Substrate (doped)Inter Level DielectricMold compoundBond wire Min 8m mmHigh Voltage Capacitor ConstructionPackage/ designationCreepage mmClearance mmNarrow body SOIC/ D4.84.3 Gull wing / DUB6.8 6.1Wide body SOIC/ DW8.1 8.3 Creepage distance: Shortes

18、t distance between two conductive input to output leads measured along surface of insulation.Clearance distance: Shortest distance between two conductive input to output leads measured through air (line of sight).Note: Package-changed and now allows 8.3mm min !Actual Die-PictureIts all capacitiveAll

19、 isolated couplers can be modeled as I/O and capacitive coupled (active or parasitic)Capa-citiveISO72XInductiveADuM1xxxGMRIL7xxOpticalHCPL-07xxCIO1 pF1 pF1.1 pF0.6 pFe, materialSiO2=4.5 Polyimide=2.8Polyimide=2.8Mold comp.e=3.6CapacitiveOpticalGMRInductiveSource: TI App note SLLA198 parametersMed.Pe

20、rf. OptoHighPerf. OptoMagnetic CapacitiveSignaling RateMbpss50Mbps150Mbps 200MbpsPropagation Delay Time100ns20ns32ns12nsPulse Width Distortion35ns2ns2ns1.5nsCh-Ch-skew40ns16ns2ns1.6nsPart-Part-Skew40ns20ns10ns2nsCompetitive ComparisonReliability (1/2)Med.Perf. OptoHighPerf. OptoMagnetic CapacitiveES

21、D on all PinsNo specNo spec / 2kVNo spec / 2kV4kVCM Transient Immunity5kV/us20kV/us25kV/us25kV/usTemperature-40.85oC-40.125oC -40.125oC -55.125oCCompetitive ComparisonReliability (2/2)60% confidence90% confidenceTech-nologyAmbient Temp.MTTF yearsFITMTTF yearsFITCapa-citive125oC56392122555055oC439520

22、0.31758080.7Magnetic125oC33583417466555oC2608250.441356060.84Optical125oC20572781439150oC290394115990Sample size / failures: ISO721: 45447 / 0; ADuM1201: 35411 / 1; HCPL-0721: 160 / 0Competitive ComparisonMagnetic ImmunityIEC 61000-4-8 1KHz Field Frequency 106 x higher Immunity than ADUM1100Source:

23、TI App note SLLA181A on above link for web info)E-field immunity Test ReportE-field immunity Test ReportMagneticISO7221C1Mbps: Comparison of Radiated Noise Spectrum Antenna HorizontalMagnetic: 1Mbps operation 5V VccISO7221: 1Mbps operation 5V VccEN55022 Class B Radiations Testing25Mbps: Comparison o

24、f Radiated Noise Spectrum Antenna HorizontalMagnetic: 25Mbps operation 5V VccISO7221: 25Mbps operation 5V VccEN55022 Class B Radiations TestingCompetitive Comparison High Voltage LifetimeSource: TI App note SLLA197 expectancy:ISO72x CompetitionISO72xADUM1100Competitive Comparison High Voltage Lifeti

25、meUsing widely accepted E-Model methodologyADUM1100ISO72xISO72x: Life expectancy is 28 years at 560Vpeak or 400VrmsCompetition: Life expectancy 30khIcc ComparisonFigure of Merritt:Bandwidth per Supply CurrentCompetitive Comparison Power Up/DownISO721ADUM1100Power up behavior:Vcc2 power supply is onI

26、nput state is L Ch 1 is Output: Transition from failsafe H to LCh2 is Vcc1 being turned on, typical turn on time is in milli sec.Power down behavior:Vcc2 power supply is onInput state is L Ch 1 is Output: Transition from L to failsafe HCh2 is Vcc1 being turned off, typical turn off time is in milli

27、sec.TI Makes Isolators Easy to U Get Started TodayuEvaluation modulesuSamplesuApplications supportuIBIS modelsuData sheetsuTechnical documentationuApplication notes on:wHigh-Voltage LifetimewMagnetic Field ImmunitywISO72x Family of Digital IsolatorsuComplements TIs industrial product portfolio: inte

28、rface, data converter, DSP, MCU, amplifier, power & logicIsolated Products Stand-AloneSinglesTriplesQuadsDualsISO7240A/C/MISO7241A/C/MISO7242A/C/MISO7230A/C/MISO7231A/C/MISO7220A/B/C/MISO7221A/B/C/MISO721/MISO722/MTriplesQuadsDualsISO7440MISO7441MISO7430MISO7431MISO7420MISO7421MISO7640MISO7641MI

29、SO7630MISO7631MISO7620MISO7621M560Vpk (cont)4kV pk (transient)890Vpk+ (cont)6kV pk (transient)10kV (surge, tbc)Available todayLow-Power-versions, pin-compatible with ISO72xx560Vpk (cont); 4kV pk (transient)(Click on Product for more information)Isolated Products Integrated2nd order D D-S S Modulator

30、 (4kV)AMC120310MHzISO1176, ISO308x,ISO1x, ISO3xIsolated Transceivers RS-485(Click on Product for more information)2nd order D D-S S Modulator (6kV)AMC120420MHzIsolated RS-485Transceiverwith Integrated Transformer Driver ISO1177RTM: 1Q10Samples: 1Q10Isolated CAN Transceiver ISO1050PreviewCross-Refere

31、nce to ADISee ESP under “product family presentations” in the isolation product-folders:Continued (also in speaker notes)Single Channel Signal Isolators:ISO72x4000Vpeak Isolation560Vpeak continuousSignaling Rate Options (ISO721B: 5Mbps, ISO721: 100Mbps, ISO721M: 150 Mbps)UL 1577, IEC 60747-5-2 (VDE

32、0884, Rev. 2), IEC 61010-1 and CSA Approved3.3V/5V Operation (any combination)25 kV/s Transient Immunity and High Electromagnetic ImmunityFailsafe Output and High Impedance at Input and Output with Low Vcc Multi-Channel Stand-alone Isolators: Dualsx designates speed option: A = 1Mbps; B = 5Mbps; C =

33、 25Mbps; M = 150MbpsMulti-Channel Stand-alone Isolators: Triplesxxx designates speed option: A = 1Mbps; C = 25Mbps; M = 150MbpsAll in DW packagexxMulti-Channel Stand-alone Isolators: Quad-channelx designates speed option: A = 1Mbps; C = 25Mbps; M = 150MbpsAll in DW packagexxxIsolated 485 Transceiver

34、sISO308x, ISO1x, ISO3x “Standard RS-485” 3.3V and 5V half-duplex and full-duplex (176 and 180 configuration) 1Mbps and 25Mbps no IDODE outputISO1176 : Isolated RS/485 ProfiBus 5V half-duplex 25Mbps optimized for Profibus-Applications ISODE availableIsolated CAN Transceiver ISO1050 5V CAN transceiver

35、 ISO11898 compliant 3.3V/5V isolated logic interface High EM Immunity 15kV/us transient immunity Bus fault protection of -27V to 40V Dominant timeout function Thermal Shutdown protection High Input impedance with low Vcc 1Mbps ISO 485 with Transformer Driver Simple Complete Solution - ISO1177 / ISO3

36、7 / ISO3088 1Mbps / 20Mbps /40Mbps 1/8 Unit load 256 nodes on a bus Glitch-Free Failsafe (Open, Shorted, Idle) Silicon Integrated SiO2 Insulator 4kVpk / 2500Vrms Isolation, 560V working / operating UL1577, IEC 60747-5-2 (VDE 0884, rev. 2), IEC 61010-1 & CSA pendingEVM ISO1177EVM / ISO37EVM / ISO3088EVM ISO1177 ProfiBus - DecISO37 3V RS485 Q1ISO3087 5V RS485 Q13V-5V Vcc1DA2303/2304-AL (Coil