TVS - Varistors, MOVs

Part Number	Description / PDF	Quantity
VE1812K801R011 KEMET	VARISTOR 18V 800A 1812	0
VC2220K122R017 KEMET	VARISTOR 27V 1.2KA 2220	0
VP4032K122R150 KEMET	VARISTOR 240V 1.2KA 2SMD JLEAD	1779
VP4032K122R095 KEMET	VARISTOR 150V 1.2KA 2SMD JLEAD	0
VA1210K401R030 KEMET	VARISTOR 47V 400A 1210	0
VE1812K401R075 KEMET	VARISTOR 120V 400A 1812	0
VC1812K801R011 KEMET	VARISTOR 18V 800A 1812	0
VE2220K122R020 KEMET	VARISTOR 33V 1.2KA 2220	0
VA1812K801R020 KEMET	VARISTOR 33V 800A 1812	0
VE1210K251R040 KEMET	VARISTOR 68V 250A 1210	0
VE1210L401R008 KEMET	VARISTOR 15V 400A 1210	0
VC1206K201R020 KEMET	VARISTOR 33V 200A 1206	0
VC0603K300R014 KEMET	VARISTOR 22V 30A 0603	5689
VC1812L501R008 KEMET	VARISTOR 15V 500A 1812	0
VE0805K121R014 KEMET	VARISTOR 22V 120A 0805	11787
VE0805K121R020 KEMET	VARISTOR 33V 120A 0805	0
VE1206K201R025 KEMET	VARISTOR 39V 200A 1206	42
VE1812K801R017 KEMET	VARISTOR 27V 800A 1812	0
VC1812K601R040 KEMET	VARISTOR 68V 600A 1812	4111
VA0805K121R017 KEMET	VARISTOR 27V 120A 0805	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