ESD保护设计研讨会.pptx

ESD Protection Design Seminar Jim SutherlandSenior Applications EngineerOutline What is ESD? What damage can it cause? Why is the problem growing? What are the issues for the designer? How can we measure it? How can we protect equipment from ESD?What Is ESD?ESD = Electro Static DischargeGenerationTriboelectric (friction causes accumulation of charge)Induction (field induces charge)DischargeDielectric (air) breakdown Electric field increases when charged bodies approach each other Current flow into circuitry ESD Damage of ICsPermanentOxide breakdown, shorts, opens, latch-upTemporaryLatch-up, ground bounceLatentDegradation from an ESD event ESD problem is growingCircuits/SystemsOld - Robust ICs Low speed signalsNew - Sensitive ICs High speed signalsEnvironmentOld - Manufacturing / Corporate New - Home / Outdoors / PersonESD Issues for the Designer Must meet ESD specificationsSelect ESD tolerant componentsMinimize signal degradation (from R,L C)Board space / weight / proper designComponent costAssembly costLifetime cost (stability)Test the systemInternational ESD StandardsHuman Body Model (HBM) - for devicesEIA/JESD22-A114-AANSI/EOS/ESD-S5.1-1993MIL-STD-883 (method 3015)IEC 1000-4-2:1995 - for systemsMachine Model (MM) - less commonEIA/JESD22-A115-AANSI/EOS/ESD-S5.1-1993Charge Device Model (CDM) - less commonJESD22-c101Human Body Model (HBM)Discharge from 100pF capacitor through 1.5 kOhm resistor6 ESD pulses3 positive, 3 negative 1 sec separationPin-to-pin testingN(N-1)/2 combinationsUsed for component characterizationWidely usedHBM Current WaveformRise Time: 2 nS Tr 10 nSIEC 1000-4-2:1995 StandardDischarge from 150 pF capacitor through 330 ohm resistor6 ESD pulses3 positive, 3 negativeUsed for system characterization“Contact” v. “Air” dischargeDifferent levelsDifferent applications60nsIEC 1000-4-2 Current WaveformVery fast rise time: Tr 1nSIEC 1000-4-2 Test LevelsContact discharge is the preferred test method - air di