TVS - Varistors, MOVs

Part Number	Description / PDF	Quantity
VA1210K401R017 KEMET	VARISTOR 27V 400A 1210	0
VE1206K201R014 KEMET	VARISTOR 22V 200A 1206	0
VE0805K121R025 KEMET	VARISTOR 39V 120A 0805	0
VE2220K501R115 KEMET	VARISTOR 180V 500A 2220	0
VC1210K251R040 KEMET	VARISTOR 68V 150A 1210	0
VC0805L121R008 KEMET	VARISTOR 15V 120A 0805	0
VG1210S020R014 KEMET	VARISTOR 25V 400A 1210	0
VP3225K401R150 KEMET	VARISTOR 240V 400A 2SMD JLEAD	3745
VE1812K401R050 KEMET	VARISTOR 82V 400A 1812	0
VE1812K801R014 KEMET	VARISTOR 22V 800A 1812	0
VE1206M151R002 KEMET	VARISTOR 4V 150A 1206	1108
VP4032K122R060 KEMET	VARISTOR 100V 1.2KA 2SMD JLEAD	0
VE2220K122R025 KEMET	VARISTOR 39V 1.2KA 2220	0
VE1206K201R011 KEMET	VARISTOR 18V 200A 1206	0
VE1210K251R060 KEMET	VARISTOR 100V 250A 1210	0
VP3225K401R060 KEMET	VARISTOR 100V 400A 2SMD JLEAD	0
VA0805K121R014 KEMET	VARISTOR 24V 120A 0805	0
VE0805K121R030 KEMET	VARISTOR 47V 120A 0805	28
VG0805S020R014 KEMET	VARISTOR 25V 100A 0805	0
VE2220K122R011 KEMET	VARISTOR 18V 1.2KA 2220	0

TVS - Varistors, MOVs

1. Overview

Transient Voltage Suppressors (TVS), Varistors, and Metal Oxide Varistors (MOVs) are critical components for protecting electronic circuits from voltage spikes and electrostatic discharge (ESD). These devices clamp excessive voltage to safe levels, preventing damage to sensitive components. TVS diodes are semiconductor-based solutions with fast response times, while Varistors (including MOVs) use nonlinear resistive materials to absorb energy. Their importance spans industries like telecommunications, automotive, and consumer electronics, ensuring reliability in environments exposed to electrical surges.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
TVS Diodes	Unidirectional/bidirectional clamping, sub-nanosecond response time, low leakage current	Communication interfaces (USB, HDMI), microcontrollers, power supplies
Zinc Oxide Varistors	High energy absorption, voltage-dependent resistance, aging characteristics	Power line protection, industrial motor drives, surge protection strips
MOVs	Specialized varistors with metal oxide ceramics, optimized for AC/DC applications	Appliances, LED lighting, renewable energy systems

3. Structure and Composition

TVS diodes employ a PN junction semiconductor structure with doping profiles optimized for breakdown characteristics. Varistors consist of polycrystalline ceramic materials (typically zinc oxide grains with additives) sandwiched between metal electrodes, encapsulated in epoxy or molded housings. MOVs use similar materials to varistors but with enhanced grain boundary engineering for improved voltage clamping. All devices incorporate termination coatings (e.g., silver, tin) for PCB mounting compatibility.

4. Key Technical Parameters

Parameter	Description	Importance
Clamping Voltage (V_CLAMP)	Voltage level during surge conduction	Determines protection level for downstream components
Response Time	Time to transition from blocking to clamping mode	TVS: 0.5-10 ns; MOVs: 10-50 ns
Energy Absorption (W_ADM)	Maximum surge energy handling capability	Measured in joules (J), critical for industrial applications
Leakage Current	Off-state current at rated voltage	Impacts power efficiency, typically <100 A

5. Application Fields

Key industries include:

Consumer Electronics: Smartphone charging circuits, TV power supplies
Industrial Automation: PLCs, motor drives, sensor interfaces
Automotive: ECU protection, CAN bus interfaces, battery management systems
Renewable Energy: Solar inverters, wind turbine controllers

Case Study: MOVs in smart meters provide 10kA surge protection against grid transients.

6. Leading Manufacturers and Products

Manufacturer	Representative Product	Key Specifications
Littelfuse	SM712-02	12A, 13.3V clamping, bidirectional TVS for RS-485
Bourns	V14450A	14mm MOV, 450VAC, 210J energy rating
STMicroelectronics	TV05C060	0.5W, 6V, ultra-small TVS for IoT devices

7. Selection Guidelines

Key considerations:

Operating voltage vs. clamping voltage margin
Surge current requirements (8/20 s waveform standard)
Package size constraints (SMD vs. through-hole)
Environmental conditions (temperature, humidity)
Lifespan expectations (MOVs degrade with repeated surges)

8. Industry Trends

Emerging trends include:

Miniaturization: Sub-0201 TVS devices for mobile applications
Higher energy density: MOVs with >1000J/cm absorption
Integration: Combined ESD and surge protection solutions
Automotive focus: AEC-Q qualified devices for 48V systems
Green manufacturing: Lead-free and RoHS-compliant materials