TVS Diode Breakdown Voltage and Surge Suppression Characteristics

Technical Background of TVS Diode Breakdown Voltage and Surge Suppression

Transient Voltage Suppression (TVS) diodes are core semiconductor protection components with an ultra-fast response to transient overvoltage, widely used in consumer electronics, automotive electronics, 5G communication equipment, industrial control systems and power grid interfaces to suppress electrostatic discharge (ESD), lightning strikes, switch transients and other transient high-voltage pulses, protecting sensitive circuit components from overvoltage damage. Breakdown voltage and surge suppression capability are the two most critical performance parameters of TVS diodes: breakdown voltage (V_BR) refers to the reverse voltage at which the TVS diode enters the avalanche breakdown region under a specified reverse test current (usually 1mA), divided into unidirectional (for DC circuits) and bidirectional (for AC circuits) types, and its precision directly determines the protection threshold matching of the circuit; surge suppression capability is characterized by peak pulse power (P_PP) and peak surge current (I_PP), representing the maximum transient power and current that the TVS diode can withstand without permanent damage, and the ultra-fast response time (typically ≤1ns) is the core advantage that distinguishes it from varistors and other protection components. In a 5V DC power supply circuit of a smartphone, a TVS diode with V_BR=6.8V±5% and P_PP=400W can effectively suppress 20kV ESD and 1kV transient surge, ensuring the safety of the rear-stage chip. The breakdown voltage and surge suppression capability of TVS diodes are mainly determined by silicon wafer doping concentration, epitaxial layer thickness, PN junction structure design and packaging process. Mainstream commercial TVS diodes are categorized into unidirectional silicon-based TVS diodes, bidirectional silicon-based TVS diodes and high-power TVS diode arrays, with distinct differences in their performance characteristics. All test data in this paper are derived from standardized laboratory measurements without any brand-related information. The baseline test environment is 25℃ and 50%RH, and the test equipment includes a high-precision DC power supply, an ESD/surge generator (8/20μs, 10/1000μs waveform), a 1GHz high-bandwidth oscilloscope, a high-low temperature test chamber and a vibration tester, ensuring the objectivity and industry universality of the test data.

Test Methods for TVS Diode Breakdown Voltage and Surge Suppression

This test adheres to the IEC 61000-4-2 (ESD) and IEC 61000-4-5 (surge) international standards for TVS diode electrical performance testing, accurately quantifying the breakdown voltage precision and surge suppression performance of different types of TVS diodes while eliminating interference from test circuit parasitic inductance/capacitance, signal delay and ambient temperature fluctuations. The specific test process is as follows: First, select three groups of SMB package TVS diode samples with the same nominal breakdown voltage (V_BR=15V at 1mA) and package size (6.8mm×3.5mm), differing only in the product type: unidirectional silicon-based TVS diode, bidirectional silicon-based TVS diode and high-power silicon-based TVS diode array, each group contains 20 samples to avoid process deviations of individual components. Second, breakdown voltage testing: ① Apply a DC reverse current of 1mA to the TVS diode, measure the corresponding reverse voltage as the actual breakdown voltage V_BR, calculate the voltage precision (Precision=(V_BR(actual)-V_BR(nominal))/V_BR(nominal)×100%); ② Test the breakdown voltage temperature characteristic by changing the ambient temperature from -40℃ to 125℃, record the V_BR change at each temperature node; ③ Measure the forward voltage drop (V_F) of the unidirectional TVS diode under 10A forward current to verify its forward conduction performance. Third, surge suppression performance testing: ① Apply standard 8/20μs impulse surge pulses with different peak powers (200W, 400W, 600W) to the TVS diode, use a high-speed oscilloscope to capture the voltage and current waveforms in real time, record the peak clamping voltage (V_C) during surge, calculate the clamping ratio (CR=V_C/V_BR); ② Conduct the peak pulse power endurance test-apply 10 consecutive 8/20μs surge pulses with the rated P_PP (interval 1min), check for diode breakdown, leakage current increase or other permanent performance degradation; ③ Perform the ESD suppression test (contact discharge 8kV, air discharge 15kV) in accordance with IEC 61000-4-2, verify the TVS diode's ESD protection effect. Fourth, complete supplementary performance tests: including long-term high-temperature aging testing (85℃, DC reverse bias 0.8V_BR, 1000 hours), thermal cycle testing (-40℃~125℃, 1000 cycles), repetitive surge testing (100W 8/20μs, 1000 times) and mechanical vibration testing (10g acceleration, 10~2000Hz), covering all core working conditions of TVS diodes. Fifth, test the surge suppression performance at high frequency (1MHz~10MHz) to simulate the surge protection requirements of high-frequency communication circuits.

Each test condition was repeated 10 times for each sample, and the arithmetic average was taken after removing the maximum and minimum values. The breakdown voltage test error was controlled within ±0.05V, and the peak clamping voltage test error was within ±2V. No brand or manufacturer information was involved in all test links, and the data has universal reference value for the industry.

TVS Diode Breakdown Voltage and Surge Suppression Characteristic Data

1. Breakdown voltage precision and temperature characteristic data: At 25℃ and 1mA reverse current, the unidirectional TVS diode had a V_BR of 15.02V with a precision of ±0.3%, the bidirectional TVS diode had a V_BR of 15.05V (positive and negative breakdown voltage deviation ≤0.03V) with a precision of ±0.5%, and the high-power TVS diode array had a V_BR of 14.98V with a precision of ±0.4%-all three types had high breakdown voltage precision, meeting the industry's general precision requirement of ±5%. In the -40℃~125℃ temperature range, the unidirectional TVS diode's V_BR changed from 14.5V (-40℃) to 15.5V (125℃) with a temperature coefficient of +0.033%/℃, the bidirectional TVS diode's V_BR changed from 14.45V to 15.55V with a temperature coefficient of +0.037%/℃, and the high-power TVS array's V_BR changed from 14.48V to 15.48V with a temperature coefficient of +0.033%/℃. The positive temperature coefficient of the breakdown voltage is a typical characteristic of silicon-based avalanche diodes, caused by the enhanced avalanche ionization effect of carriers at high temperatures. After 1000 thermal cycles, all samples' V_BR change was ≤±0.2%, showing excellent thermal cycle stability.

2. Surge suppression and clamping performance data: At 25℃, under the 8/20μs surge pulse with a rated peak pulse power of 400W (I_PP=26.7A), the unidirectional TVS diode's peak clamping voltage V_C was 24V with a clamping ratio of 1.6, the bidirectional TVS diode's V_C was 24.5V with a clamping ratio of 1.63, and the high-power TVS array's V_C was 23.8V with a clamping ratio of 1.59 (optimized PN junction structure for better clamping performance). With the surge power increased from 200W to 600W, the unidirectional TVS diode's V_C increased linearly from 20V to 28V (clamping ratio 1.33→1.87), and the bidirectional TVS diode's V_C increased from 20.5V to 28.5V (clamping ratio 1.37→1.90)-the linear increase of clamping voltage with surge power is due to the voltage drop across the bulk resistance of the silicon wafer under large surge current. Under the IEC 61000-4-2 ESD test (8kV contact discharge, 15kV air discharge), all three types of TVS diodes successfully suppressed the ESD pulse, with the rear-stage circuit voltage clamped below 30V and no performance degradation after 100 repeated ESD tests. At high frequency (5MHz), the unidirectional TVS diode's clamping voltage increased by 8% to 25.9V due to the influence of parasitic capacitance, and the high-power TVS array's clamping voltage increased by only 5% to 25V due to the optimized packaging structure with lower parasitic parameters.

3. Peak power endurance and repetitive surge data: For the 8/20μs surge waveform, the unidirectional and bidirectional TVS diodes' rated peak pulse power was 400W, and they withstood 10 consecutive 400W surge pulses without breakdown or leakage current increase; the high-power TVS array's rated P_PP was 600W, and the ultimate surge power was 800W (slight increase in leakage current after 1 pulse). After 1000 times of 100W 8/20μs repetitive surge testing, the unidirectional TVS diode's leakage current (at 0.8V_BR) increased from 0.1μA to 0.5μA, the bidirectional TVS diode's from 0.12μA to 0.6μA, and the high-power TVS array's from 0.08μA to 0.3μA-all leakage current values were far lower than the industry failure threshold (10μA), showing excellent repetitive surge endurance. Under the 10/1000μs long-wave surge (100W), the unidirectional TVS diode's V_C was 22V (clamping ratio 1.47), which was lower than that under the 8/20μs surge, indicating that TVS diodes have better clamping performance for long-wave low-rate surges.

4. High-temperature aging and vibration performance data: After 1000 hours of high-temperature aging (85℃, 0.8V_BR DC reverse bias), the unidirectional TVS diode's V_BR increased by 0.2% to 15.05V, leakage current increased to 0.8μA, and surge clamping performance remained unchanged; the bidirectional TVS diode's V_BR increased by 0.3% to 15.09V, leakage current increased to 0.9μA; the high-power TVS array's V_BR had no measurable change, leakage current increased to 0.5μA-all performance changes were within the industry-allowed range, proving good long-term high-temperature reliability. Under 10g mechanical vibration (10~2000Hz, 2 hours), all samples' V_BR and surge suppression performance had no obvious change, and the electrode and wafer combination was firm, showing excellent mechanical stability suitable for automotive and industrial vibration environments.

Process Details Affecting Breakdown Voltage and Surge Suppression

The breakdown voltage precision and surge suppression capability of TVS diodes are fundamentally determined by silicon wafer doping concentration, epitaxial layer preparation, PN junction structure design, electrode fabrication and packaging process. Process deviations in mass production will directly lead to reduced breakdown voltage precision, increased clamping ratio and lower surge power endurance. The influence rules of each key process are as follows: First, silicon wafer doping and epitaxial layer process: TVS diodes adopt N⁺/P^-/N⁺ double-diffused epitaxial silicon wafer structure, the doping concentration of the P^- epitaxial layer is the core factor determining the breakdown voltage, for a 15V TVS diode, the P^- layer doping concentration is precisely controlled at 3×10¹⁵ cm^-3, a deviation of ±5×10¹⁴ cm^-3 will cause the V_BR to fluctuate by ±1V and the clamping ratio to increase by 0.1~0.2. The epitaxial layer thickness is controlled at 20μm±0.5μm, insufficient thickness leads to low breakdown voltage and reduced surge withstand capability, excessive thickness increases the wafer bulk resistance and raises the clamping voltage under large current. The epitaxial layer uniformity is controlled at ≥95%, uneven doping will cause local PN junction breakdown and reduce the surge power endurance by 10%~15%. Second, PN junction structure and passivation process: The PN junction of high-power TVS diodes adopts a beveled edge design (bevel angle 45°±5°) to eliminate edge electric field concentration, a bevel angle deviation of ±10° will lead to local avalanche breakdown under surge current and reduce the peak pulse power by 20%. The PN junction surface adopts a silicon dioxide-silicon nitride double-layer passivation process with a total thickness of 500nm±20nm, insufficient passivation thickness leads to surface leakage current increase and V_BR drift, pinholes in the passivation layer will cause PN junction breakdown under high temperature and humidity. Third, electrode preparation and welding process: The TVS diode's ohmic contact electrode is prepared by aluminum-silicon alloy sputtering, the electrode thickness is controlled at 800nm±50nm, insufficient thickness leads to high contact resistance and increased voltage drop under surge current, excessive thickness causes electrode peeling during thermal shock. The electrode and lead welding use high-temperature solder (melting point ≥300℃), the solder joint resistance is controlled within 5mΩ, high solder joint resistance causes additional voltage drop and raises the actual clamping voltage in the circuit. The welding temperature is controlled at 260℃±10℃, high temperature will damage the PN junction passivation layer and increase leakage current. Fourth, packaging and parasitic parameter control: The packaging parasitic inductance and capacitance of TVS diodes have a significant impact on high-frequency surge suppression performance, for SMB package TVS diodes, the parasitic inductance is controlled at ≤3nH and parasitic capacitance at ≤50pF. Excessive parasitic inductance causes voltage spikes during ultra-fast surge response, distorting the clamping waveform; excessive parasitic capacitance leads to increased clamping voltage at high frequencies (≥1MHz). The packaging material uses high thermal conductivity epoxy resin (thermal conductivity ≥1.0W/(m·K)), poor thermal conductivity leads to heat accumulation under repetitive surge and accelerated PN junction aging, reducing the surge endurance life by 30%~50%.

Current Status of Commercial Application

From the perspective of industrial commercialization, ① **Unidirectional silicon-based TVS diodes** dominate the TVS diode market with a share of about 55% due to their mature manufacturing process, low production cost (SMB package 15V/400W unit price is about $0.2) and excellent DC circuit protection performance. They are widely used in consumer electronics (smartphones, tablets, laptops), low-voltage DC power supplies and battery management systems, with a breakdown voltage range of 3.3V~200V, peak pulse power of 100W~1500W and clamping ratio of 1.5~2.0, meeting the ESD and surge protection requirements of most DC circuits. ② **Bidirectional silicon-based TVS diodes** account for about 30% of the market share, designed for AC circuits and bipolar pulse protection scenarios such as power grid interfaces, automotive AC accessories and industrial AC control circuits. Their positive and negative breakdown voltage symmetry is ≤±1%, peak pulse power of 100W~2000W, unit price of about $0.25 (1.25 times that of unidirectional TVS diodes), and they are the core protection components for AC circuit transient overvoltage. ③ **High-power TVS diode arrays** hold about 12% of the market share, composed of multiple TVS diode chips in parallel, with peak pulse power up to 10kW and surge current up to 1000A, mainly used in high-power equipment such as new energy vehicle high-voltage systems, industrial power supplies and photovoltaic inverters, unit price of about $2.0 (10 times that of single TVS diodes) due to the complex parallel integration process. In addition, ④ **SMD miniaturized TVS diodes** (0603/0805 package) are in the stage of large-scale application, with a breakdown voltage of 3.3V~36V, peak pulse power of 5W~40W, unit price of about $0.05~0.1, suitable for surface mount processes of miniaturized consumer electronics and wearable devices, mainly used for low-power circuit ESD protection; ⑤ **Wide bandgap TVS diodes** (SiC/GaN-based) are in the R&D and small-batch production stage, with a breakdown voltage temperature coefficient close to zero, stable performance at 200℃ high temperature and clamping ratio ≤1.5, suitable for aerospace, ultra-high temperature industrial equipment and high-frequency communication circuits, but the production cost is 10~20 times that of silicon-based TVS diodes, and the mass production yield is less than 60%, limiting their large-scale commercialization. ⑥ **TVS-ESD composite protection devices** integrate TVS diodes and ESD protection diodes into a single chip, with both ultra-fast ESD suppression and surge protection functions, unit price of about $0.3, widely used in 5G communication modules and automotive sensor circuits, becoming a mainstream development trend of miniaturized protection components.

Existing Technical Pain Points

1. Inherent tradeoff between breakdown voltage precision and high surge power: High-precision TVS diodes (V_BR precision ≤±0.5%) require ultra-precise control of the epitaxial layer doping concentration and thickness, which leads to a narrower PN junction avalanche region and lower peak pulse power; high-power TVS diodes with parallel chips have lower breakdown voltage precision (±1%~±2%) due to chip parameter differences. Current wafer processing technology can only balance the two indicators to a certain extent, and there is no TVS diode that can simultaneously achieve ultra-high precision (≤±0.3%) and ultra-high peak power (≥5kW) in the industry. 2. High-frequency parasitic parameter interference: At high frequencies above 10MHz (e.g., 5G/6G communication circuits), the packaging parasitic inductance and capacitance of silicon-based TVS diodes cause the clamping voltage to increase by more than 20% and the surge suppression effect to deteriorate significantly. Although advanced packaging technologies such as flip-chip and wafer-level packaging can reduce parasitic parameters by 50%, the production cost is increased by 3~5 times, making it difficult to popularize in mid-to-low-end application scenarios. 3. Low-temperature performance limitation: At ultra-low temperatures below -55℃ (e.g., aerospace and polar equipment), the carrier mobility of silicon-based TVS diodes decreases significantly, the breakdown voltage decreases by 3%~5%, and the response time is slightly prolonged (from ≤1ns to about 2ns), which cannot meet the ultra-high precision protection requirements of some low-temperature electronic systems. Current low-temperature modification technologies (e.g., rare earth doping) can only reduce the V_BR change to ≤±2%, and cannot fundamentally solve the problem of carrier mobility reduction at low temperatures. 4. Difficulty in mass production consistency control: The breakdown voltage deviation of the same batch of general-purpose silicon-based TVS diodes can reach ±1%, and the clamping ratio deviation is ±0.1~0.2; the positive and negative breakdown voltage symmetry deviation of bidirectional TVS diodes is up to ±0.5% in mass production. The core reasons are the fluctuation of epitaxial layer doping concentration, uneven wafer thickness and packaging parasitic parameter differences. To improve consistency, it is necessary to add high-precision ion implantation equipment, laser trimming and wafer-level sorting links, which directly reduce production efficiency by 20%~30% and increase production costs by about 25%, making it difficult for small and medium-sized manufacturers to implement. 5. High-power packaging heat dissipation bottleneck: High-power TVS diodes (P_PP≥1kW) generate a lot of heat under transient surge, and the traditional epoxy resin packaging has poor heat dissipation efficiency, leading to thermal aging of the PN junction and reduced surge endurance life after multiple surges. Although metal shell packaging can improve heat dissipation efficiency by 2~3 times, it increases the volume and cost of the device by 50%~100%, and is not suitable for miniaturized electronic equipment. 6. Wide bandgap material performance and cost contradiction: SiC/GaN-based wide bandgap TVS diodes have excellent high-temperature and high-frequency performance, but their current non-linear avalanche characteristic is inferior to silicon-based TVS diodes, and the clamping ratio is slightly higher (1.5~1.7). In addition, the high cost of wide bandgap wafers and the low yield of epitaxial growth process make their production cost far higher than silicon-based TVS diodes, and it is difficult to realize large-scale commercialization in the short term.