Features of TVS Diodes and Differences from Other ESD Protection Elements | Basic knowledge concerning ESD (Electrostatic Discharge) countermeasures and TVS Diodes (ESD Protection Devices)

ESD (Electrostatic Discharge) protective devices and countermeasure components
Differences Between TVS Diodes and Zener Diodes
Differences Between TVS Diodes, Varistors, and Suppressors
Video TVS Diodes: Protection of Electronic Components from ESD
TVS Diode (ESD Protection Device) Product Information
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ESD (Electrostatic Discharge) protective devices and countermeasure components

The main function of an TVS Diodes is to enable ESD that enters a device to escape to ground. If there is no TVS Diode, ESD which has a voltage of several thousand volts will be applied directly to the internal ICs.

This figure illustrates the mechanism by which ESD intrudes from the interface of an electronic device and is applied to an internal IC when an ESD protection element (TVS diode) is not used.

When an TVS Diodes is installed between an external interface and an IC in order to protect the IC, the input to the IC will be grounded via the TVS Diodes, enabling ESD to escape to ground. Under the normal drive voltage (several volts), the IC is isolated from ground, so data communication is not impaired. The ability to ground an IC circuit when several tens to thousands of volts are applied to it, and also to isolate it from ground when several volts are applied to it, is a necessary function of an TVS Diodes.

This figure illustrates how a TVS diode placed on a data line acts in cases with and without ESD. During normal operation, almost no current flows to the TVS diode, and data entering via the interface is transmitted to the IC. When ESD intrudes, the data is sent to the IC, and the TVS diode shunts the high-ESD voltage to GND.

The following graph shows the difference between the voltages at the IC side depending upon whether or not an TVS Diodes is installed. Here, an 8 kV ESD is generated using an ESD gun containing a capacitor and internal resistance, and the voltage after it has passed through the device is measured using an oscilloscope. From the waveform of the graph, it can be seen that the existence of the TVS Diodes greatly reduces the voltage applied to the IC side.

This graph compares the voltage (vertical axis) and its duration (horizontal axis) when ESD is applied to test devices with and without a TVS diode. This shows that when a TVS diode is present, the high ESD voltage is quickly shunted and that state is maintained. The ESD testing equipment setup is also shown. Here, high voltage was applied to the test device using an ESD gun, and the voltage was measured with an oscilloscope via an attenuator.

Differences Between TVS Diodes and Zener Diodes

A TVS diode is a type of Zener diode.
The difference between a constant voltage diode and a TVS diode is that while a constant voltage diode is used to stabilize the voltage, a TVS diode is used to prevent transient voltages such as ESD.
In addition, while ESD-related specifications are listed for a TVS diode as shown in the items in the red frame below, such specifications are not listed for a constant voltage diode.

Parameter	Reverse Stand-off Voltage	Channel Leakage Current	Break down voltage	ESD per IEC 61000-4-2 (air)	ESD per IEC 61000-4-2 (contact)	ESD per IEC 61000-4-5 (Surge) (8/20μs)	Capacitance
Symbol	V_RWM	I_leak	V_br	V_esd	V_esd	I_pp	C
Unit	V	uA	V	kV	kV	A	pF
Condition		VP_in1=5V, VP_in2=0V	I_br=1mA, P_in1 to P_in2	Ta=25℃	Ta=25℃		VP_in1,2=0V,f = 1MHz, Between Channel pins
LXES1UTAA1-157 LXES1UTBB1-157	+/- 6.0	1.0 (max)	7 (min)	+/- 15	+/- 8	1.5	0.5

Differences Between TVS Diodes, Varistors, and Suppressors

Next, the differences between TVS diodes, varistors, and suppressors are compared from various perspectives. The applications and features of each ESD protection element are also summarized.

Comparison of varistors, suppressors, and TVS diodes

The table below shows the differences in usage locations, application examples, advantages, and disadvantages for TVS diodes, varistors, and suppressors.

	Varistor	Suppressor	TVS Diodes
Location of use	Power supplies, data lines	High output RF signal lines, data lines	Power supply lines, data lines, low-output RF signal lines
Application example	High voltage power supply lines, etc.	Antenna power supply lines for Wi-Fi® and Bluetooth®, etc.	USB data lines USB and GPS power supply lines, etc.
Benefits	High discharge characteristic (limited to high capacitance products)	Low capacitance of 0.1 pF or less	High discharge characteristic Fast response when ESD intrudes
Disadvantages	Challenging to use with low capacitance (0.5 pF or less) Cannot be used in a high output RF port	Does not operate when low voltage is applied	Cannot be used in a high output RF port

Varistor applications and features

Varistors are ceramic-based ESD protection elements and are often used in power supply ports and data lines.
Note that while higher capacitance products have superior discharge characteristics, the large electrostatic capacitance of varistors renders them unusable on RF ports that require low-capacitance products of 0.5 pF or less.
In addition, while their low cost is an advantage, repeated ESD application can potentially cause degradation of insulation resistance (short-circuit).

Suppressor applications and features

Suppressors are ceramic-based ESD protection elements used for high-output RF ports (antenna ports) such as Wi-Fi® and Bluetooth®, as well as data lines, etc. Their extremely low capacitance of 0.1 pF or less makes them suitable as ESD countermeasures on high-speed signal transmission lines.
However, disadvantages compared to TVS diodes include the fact that ESD protection does not operate at low voltages, and the response speed is slow.

TVS diode applications and features

TVS diodes are semiconductor-based ESD protection elements and are used for ESD protection in data lines such as power supply ports, USB ports (USB 1.1 to USB 3.2) and HDMI ports (HDMI 1.0 to 2.0), low-output power RF ports such as NFC, and RF ports for receive-only GPS. (See "TVS diode usage examples" on the "TVS Diodes (ESD Protection Devices)" page for details.)
TVS diodes cannot be used in high-output RF ports like suppressors, but they exhibit high discharge characteristics on low-output RF ports and GPS antenna reception lines.

When ESD intrudes, TVS diodes have a fast response speed until operation in the order of picoseconds, which is a major difference and advantage compared to varistors or suppressors. Despite costing more than varistors or suppressors, they are used as protection from ESD for data lines that perform high-speed transmission in electronic devices equipped with high-performance and high-cost ICs.

Comparison of response times during an ESD event This graph compares the response speeds of varistors, suppressors, and TVS diodes when ESD is applied. The vertical axis represents voltage (V), and the horizontal axis represents time (ns). As seen here, while varistors and suppressors have a response start time of 1.0 nanosecond or more, TVS diodes exhibit the fastest response in the order of picoseconds.

This graph compares the response speeds of varistors, suppressors, and TVS diodes when ESD is applied. The vertical axis represents voltage (V), and the horizontal axis represents time (ns). As seen here, while varistors and suppressors have a response start time of 1.0 nanosecond or more, TVS diodes exhibit the fastest response in the order of picoseconds.

TVS diodes respond on the order of picoseconds, the fastest among the three ESD protection devices.

Video TVS Diodes: Protection of Electronic Components from ESD

Watch this video to learn more about why TVS diodes are necessary, how they are used, and the features of Murata’s TVS diodes.

Murata's TVS diodes have high static electricity suppression capability. We provide products that support applications ranging from DC to high-speed transmission, as well as compact products that help reduce the circuit board area.

See "Product Lineup" on the "TVS Diodes (ESD Protection Devices) LXES T Series" page for details.

Basic knowledge concerning ESD (Electrostatic Discharge) countermeasures and TVS Diodes (ESD Protection Devices)

This website describes ESD as well as the functions, types, and characteristics of TVS diodes that act as countermeasure components against ESD.

Features of TVS Diodes and Differences from Other ESD Protection Elements

TVS Diode (ESD Protection Device) Product Information

Product Lineup

Murata’s "LXES-T Series" TVS diode has a high static electricity suppression performance.

Proposal for Miniaturization

Miniaturization of not only inductors and capacitors, but also ESD protection devices as well
Method of eliminating worries concerning the mounting of 0603 (mm) and 0402 (mm) small LGA

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TVS Diodes (ESD Protection Devices)Features of TVS Diodes and Differences from Other ESD Protection Elements