Main/OneNote/OSD/Research/ESD.md

Notes to ESD essentials by TI

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

Chapter 2 - ESD Working Voltage

Also known as Reverse Standoff Voltage

Indicated by red: BreakDown Voltage. Any voltage larger than this will make the diode conductive.

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

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.

Clamping Voltage

This is the important measure, because it describes the voltage protection capability of the clamping diode.

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

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:

This means for a highspeed signal it is extremely important that the parasitic capacitance is small.

General overview:

ESD Protection selection

![Step 4: Determine TLP Clamping Voltage ESD Essentials <16V <16V Battery Charger Fails: 20V TLP USB 2.0 Switch Fails: 16V TLP Bidirectional Any <20Vat 16A TLP

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)