TVS - Varistors, MOVs

Part Number	Description / PDF	Quantity
820544611 Würth Elektronik Midcom	DISK VARISTOR STANDARD 14MM; 460	0
820541406 Würth Elektronik Midcom	DISK VARISTOR STANDARD 14MM; 14V	0
82541250 Würth Elektronik Midcom	VARISTOR 39V 200A 1206	1788
820412001 Würth Elektronik Midcom	DISK VARISTOR HIGHSURGE 10MM; 20	0
820545001 Würth Elektronik Midcom	DISK VARISTOR STANDARD WE-VD 14M	0
820544211 Würth Elektronik Midcom	DISK VARISTOR STANDARD 14MM; 420	32
82536070 Würth Elektronik Midcom	VARISTOR 13.5V 30A 0603	2356
820444211E Würth Elektronik Midcom	DISK VARISTOR HIGHSURGE 14MM; 42	0
820474611 Würth Elektronik Midcom	DISK VARISTOR HIGHSURGE WE-VD 7M	0
82531400 Würth Elektronik Midcom	VARISTOR 70V 200A 1206	2042
820573011 Würth Elektronik Midcom	DISK VARISTOR STANDARD 7MM; 300V	1000
820441311E Würth Elektronik Midcom	DISK VARISTOR HIGHSURGE 14MM; 13	729
82556170 Würth Elektronik Midcom	VARISTOR 27V 30A 0603	0
820415511B Würth Elektronik Midcom	DISK VARISTOR HIGHSURGE WE-VD -	0
820513811 Würth Elektronik Midcom	DISK VARISTOR STANDARD 10MM; 385	0
820551311 Würth Elektronik Midcom	DISK VARISTOR STANDARD 5MM; 130V	0
820475001 Würth Elektronik Midcom	DISK VARISTOR HIGHSURGE 7MM; 50V	0
820574211 Würth Elektronik Midcom	DISK VARISTOR STANDARD WE-VD 7MM	0
82541140 Würth Elektronik Midcom	VARISTOR 24V 200A 1206	474
820511311 Würth Elektronik Midcom	DISK VARISTOR STANDARD 10MM; 130	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