TVS - Surge Protection Devices (SPDs)

Image	Part Number	Description / PDF	Quantity	Rfq
	BSPD400240D1P Eaton	SPD, 400KA, BASIC PKG., NEMA 4X	0
	SPH50SP3480WYG Eaton	SURGEPOD HEAVY DUTY UL TYPE1 SPD	0
	BSPD400240D1K Eaton	SPD, 400KA, BASIC PKG., NEMA 1 E	0
	LSP05GI277SX3316 Wickmann / Littelfuse	LIGHTING SURGE PROTECT 277V SCRW	0
	SPOD510LT Eaton	SPOD FINAL ASSEMBLY	0
	SPP40SP1240SN Eaton	SURGEPOD PRO TYPE1 SPD FOR 240V	0
	SPOD550LR Eaton	SPOD FINAL ASSEMBLY	0
	BSPM2275TNR Eaton	VARISTOR 230V 40KA MOD PLUG-IN	0
	SPOD320SR Eaton	SPOD FINAL ASSEMBLY	0
	SPH50SP3208WYG Eaton	SURGEPOD HEAVY DUTY UL TYPE1 SPD	0
	BSPM1A320D420LV Eaton	VARISTOR 40KA MODULE PLUG-IN	0
	BSPMA3240DLGR Eaton	VARISTOR SURGE ARRESTOR	0
	BSPH3600YPVR Eaton	600 VDC 3 POLE Y CONFIGURATION S	0
	SPOD320S Eaton	SPOD FINAL ASSEMBLY	0
	BSPD120480Y1P Eaton	SPD, 120KA, BASIC PKG., NEMA 4X	0
	LSP05G480S Wickmann / Littelfuse	LSP THERMALLY PROTECTED VARISTOR	0
	BSPM3150TNCR Eaton	VARISTOR 120V 40KA MOD PLUG-IN	0
	BSPM11000WER Eaton	VARISTOR 1KV 30KA MOD PLUG-IN	0
	BSPD120240D1K Eaton	SPD, 120KA, BASIC PKG., NEMA 1 E	0
	BSPM4275TNS Eaton	VARISTOR 400V 40KA MOD PLUG-IN	0

TVS - Surge Protection Devices (SPDs)

1. Overview

Transient Voltage Suppression (TVS) diodes and Surge Protection Devices (SPDs) are critical components for safeguarding electronic systems against voltage spikes and electrostatic discharge (ESD). TVS diodes are semiconductor devices designed for rapid response to transient events, while SPDs encompass a broader category of devices that protect power and signal lines in electrical systems. These components play a vital role in ensuring reliability in applications ranging from consumer electronics to industrial infrastructure.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
TVS Diodes	Fast response time (ps/ns range), low clamping voltage, unidirectional/bidirectional configurations	Communication interfaces (USB, HDMI), automotive electronics, portable devices
Metal Oxide Varistors (MOVs)	High energy absorption, nonlinear voltage-current characteristics	Power strips, industrial equipment, building wiring systems
Gas Discharge Tubes (GDTs)	High surge current capability, multi-electrode design	Telecom infrastructure, lightning protection systems
Hybrid SPDs	Combination of TVS/MOV/GDT for multi-stage protection	Renewable energy systems, smart grids

3. Structure and Composition

TVS diodes typically employ a PN junction semiconductor structure with epitaxial layers for optimized clamping performance. MOVs consist of zinc oxide grains embedded in a ceramic matrix with grain boundary layers acting as insulating barriers. GDTs utilize hermetically sealed gas chambers with precision-spaced electrodes. Hybrid devices integrate multiple technologies in a single package with isolation barriers and thermal disconnect mechanisms.

4. Key Technical Specifications

Parameter	Significance	Typical Range
Clamping Voltage	Maximum voltage during surge event	5V-2000V
Response Time	Time to activate protection	0.1ps-10ns (TVS), 1 s-10 s (SPDs)
Maximum Peak Current	Surge current handling capability	10A-100kA
Operating Temperature	Environmental durability range	-55 C to +175 C
Parasitic Capacitance	Signal integrity impact factor	0.1pF-100nF

5. Application Areas

Telecommunications (base stations, optical transceivers)
Industrial automation (PLC systems, motor drives)
Renewable energy (solar inverters, wind turbine controllers)
Consumer electronics (smartphones, IoT devices)
Automotive (CAN bus protection, battery management systems)
Power distribution (smart meters, grid infrastructure)

6. Leading Manufacturers and Products

Manufacturer	Representative Products	Key Features
STMicroelectronics	SM6T Series	600W peak power, 5V-36V working voltage
Littelfuse	SP1012 Series	Ultra-low capacitance (0.25pF), USB4 protection
Bourns	CDSOT23-SM712	Bidirectional protection, RS-485 compatibility
TE Connectivity	ProTek Devices	Automotive qualified, AEC-Q101 certified

7. Selection Guidelines

Key considerations include:
- Working voltage and power requirements
- Environmental conditions (temperature, humidity)
- Surge current expectations (per IEC 61000-4-5)
- Signal bandwidth requirements (for high-speed interfaces)
- Compliance with industry standards (UL 1449, IEC 61643)
- Failure mode preferences (fail-short vs fail-open)
Example: For industrial Ethernet applications, select a bidirectional TVS with <1nS response time and 150V clamping voltage meeting IEEE 802.3 standards.

8. Industry Trends

Emerging trends include:
- Development of SiC/GaN-based TVS for high-frequency applications
- Integration with AI-powered predictive maintenance systems
- Miniaturization for wearable electronics (0201 package formats)
- Enhanced coordination between primary/secondary protection stages
- Adoption of TVS arrays for multi-line protection in 5G infrastructure
- Improved energy efficiency with lower leakage current devices