Main/OneNote/OSD/Research/ESD.md

[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 
<O.3pF 
<O.7PF 
<0.5pF 
<5pF 
<O.2pF 
<80pF 
Device ](Exported%20image%2020231126172008-10.png)  
  

# ESD Protection selection

![ESD Selection Steps 
Was thi* 
ESD Esse tlals 
1) 
2) 
3) 
4) 
5) 
Quantify the signal range of your signal/power interface to 
determine the ESD diode's working voltage. 
Decide whether a unidirectional or bidirectional configuration 
is preferred. 
Decide the maximum capacitance can be accepted for the 
interface. 
Determine what TLP voltage the system fails at to determine 
the necessary clamping voltage of the diode. 
Ensure that the diode exceeds IEC 61000-4-2 level 4. ](Exported%20image%2020231126172008-11.png)  
![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)