[Notes to ESD essentials by TI](https://training.ti.com/esd-essentials-what-esd?context=1136983-1139548-1135647) ESD - Electrostatic discharge This happens when you're getting charged up positively and touch a conductor. Large voltages can be generated that can damage Ics. ESD diodes can be used to direct those ESD-currents into GND, before they can reach the Ics ![Circuit with ESD Protection Interface Connector ESD Diode ESD Essentials System Circuitry ](Exported%20image%2020231126172008-0.png) # Chapter 2 - ESD Working Voltage Also known as Reverse Standoff Voltage ![Working Voltage vs. Breakdown Voltage ESD ESD I-v Plot e tials ESD Diode 0:18 Protected Circuitry 0:55 16 14 12 10 4 2 0 1 2 3 4 5 6 7 8 9 10 11 voltage (V) ](Exported%20image%2020231126172008-1.png) Indicated by red: BreakDown Voltage. Any voltage larger than this will make the diode conductive. ![(Λ) αβηΙ0Λ ΥΙΙΟΙ νηι•ο ΊΙΙ' Ό νιΙΙΟΙ ΥΙΙΙΟΟΙ Λ-Ι asa a6ellO/\ uMOP>1eaJ8 Θ6ηΙOΛ 611!ΥΙ0Μ ](Exported%20image%2020231126172008-2.png) The signal level, which is used normally should be below VRWM --> like that we have below 10 nA leakage current. The working voltage of the diode you choose should be slightly higher than the largest signal. ![Bidirectional vs. Unidirectional ESD Configuration Bidirectional 1/0 Functional Diagram - GND Has a symmetric positive and negative breakdown voltage Definition Can be used for interfaces with both positive and/or negative voltage ranges Supported Interfaces (all interfaces) In I-channel ESD bidirectional ESD, any pin can be the I/O and any pin can be the ground ESD Essentials Unidirectional 1/0 GND Has a positive breakdown voltage but breaks down almost immediately in the negative direction Can only be used for interfaces that only have a positive voltage range Digital inputs, USB, HDMI and other positive signal interfaces Has better negative clamping performance than bidirectional diodes since the negative breakdown voltage is lower. ](Exported%20image%2020231126172008-3.png) # IEC 610000-4-2 ESD Rating ![ESD Standard: IEC 61000-4-2 ESO s IEC 61000-4-2 ESD *Designed for real world applications ESD Essentials 61000-4-2 HBM 20 40 60 Time (ns) 80 100 TEXAS INSTRUMENTS ](Exported%20image%2020231126172008-4.png) ## Human Body Model (HBM) ESD This is used to estimat the manufacturing, assembly and shipping. Not for the final use! ## Charge Device Model (CDM) ESD ESD discharge through charged device into ground. Also only Manufacturing, assembly and shipping. ## IEC 61000-4-2 This is the model that simulates the final use by the user. There are 4 Levels and devices next to interface connectors should use at least level 4. ![Look for the IEC 61000-4-2 Rating IEC 61000-4-2 Level 1 2 3 4 E D Ratin s Contact Voltage 2kV 6kV 8kV Air Gap Voltage 2kV 4kV 8kV 15kV 6.2 V(ESO) Humm (HBM). ANSVESDA/JEOEC Chat%d-device rncxlel (COM). JEDEC CIO' 6 Contact Discharge Discharge ESD Essentials VALUE *15000 *15000 ](Exported%20image%2020231126172008-5.png) # Clamping Voltage This is the important measure, because it describes the voltage protection capability of the clamping diode. ![Common Misconception regarding IEC Interface Connector ESD Diode IEC 610004-2 Rating measures the robustness of the diode (ex: 8kV contact Il 5kV air gap) System Circuitry be exposed to. ESD Esse v ESD clamping voltage rating measures how well the ESD diode will protect system circuitry ](Exported%20image%2020231126172008-6.png) ![Clamping Voltage on the T LP Plot — 12 ESD Essentials 22A ESD 15.5V Diode Minimize RDYN to provide better clamping voltage and protection 18 10 2 Transmission Line Pulse Plot nds 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Voltage (V) ](Exported%20image%2020231126172008-7.png) Depending on the ESD strike a different current is shunted through the diode. This results in a remaining voltage drop, which the system circuitry will be exposed to. That is the voltage that can still damage our system. --> select diode according to max voltage that system can survive. # Parasitic Capacitance ![ESD Junction Capacitance Interface Signal ESD Esse Protected Circuitry N -type P-type ](Exported%20image%2020231126172008-8.png) Because of the physics the diode can be modeled as a capacitor. Hence it will influence the circuit during normal operation. If parasitic capacitance is high it can influence the signal: ![Capacitance Effect on Signal Integrity Input Interface Signal ESD Diode ESD Essen—. Signal capacitance interference Protected Circuitry ](Exported%20image%2020231126172008-9.png) This means for a highspeed signal it is extremely important that the parasitic capacitance is small. General overview: ![Capacitance Recommendations ESD Typical Tl Recommended Interface GPIO Pushbutton Audio USB 2.0 USB 3.0 USB 3.1 Gen 2 HDMI 1.4 HDMI 2.0 Ethernet Antenna 4-20mA Loop Suggested Capacitance (C') <30pF <30pF <10pF <2.5PF <0.5pF 3.6v• Bidirectional <2.5PF <16V at 16A TLP GND USB Receptacle Polarity Configuration Capacitance Clamping Voltage IEC 61000-4-2 Rating TLP failure voltage is NOT the same as absolute maximum voltage. Absolute maximum voltage is a DC voltage while TLP is a 100ns transient. ](Exported%20image%2020231126172008-12.png)