TVS - Varistors, MOVs

Part Number	Description / PDF	Quantity
B72220S0301K551 TDK EPCOS	VARISTOR 470V 8KA DISC 20MM	750
B72207S0381K311 TDK EPCOS	VARISTOR 620V 1.2KA DISC 7MM	5945
B72207S0321K101 TDK EPCOS	VARISTOR 510V 1.2KA DISC 7MM	11880
B72210S2621K101 TDK EPCOS	VARISTOR 1KV 3.5KA DISC 10MM	1500
B72210S0681K101 TDK EPCOS	VARISTOR 1.1KV 2.5KA DISC 10MM	1775
B72225T4381K101 TDK EPCOS	VARISTOR 620V 20KA RADIAL BOX	0
B72280B0441K001 TDK EPCOS	VARISTOR 715V 100KA ENCASED DISC	0
B72220S3301K101 TDK EPCOS	VARISTOR 470V 12KA DISC 20MM	1108
B72207S0250K211 TDK EPCOS	VARISTOR 39V 250A DISC 7MM	44006
B72500T0070M060 TDK EPCOS	VARISTOR 12.5V 30A 0603	7270
B72214S2461K101 TDK EPCOS	VARISTOR 750V 5KA DISC 14MM	2850
B72205S2301K101 TDK EPCOS	VARISTOR 470V 800A DISC 5MM	11580
B72207S2381K101 TDK EPCOS	VARISTOR 620V 1.75KA DISC 7MM	0
B72220S3271K101 TDK EPCOS	VARISTOR 430V 12KA DISC 20MM	497
B72214Q0511K101 TDK EPCOS	VARISTOR 820V 6KA DISC 14MM	0
B72660M0461K093 TDK EPCOS	VARISTOR 750V 1KA 4032	2941
B72207S0200K101 TDK EPCOS	VARISTOR 33V 250A DISC 7MM	4417
B72207S0500K311 TDK EPCOS	VARISTOR 82V 1.2KA DISC 7MM	0
B72214S2551K551 TDK EPCOS	VARISTOR 910V 5KA DISC 14MM	1407
B72205U2151K501 TDK EPCOS	VARISTOR 240V 800A DISC 5MM	838

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