Name: /Tools-Info/Gdtube2pin 600 V
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GDTUBE2PIN 600V (Surge-Protect Gas Discharge Tube, SXH81-600X)

is an overvoltage protection device that uses a gas-filled ceramic enclosure and internal electrodes to clamp high-voltage transients. Under normal voltage it is non-conducting; when the voltage exceeds its breakdown voltage, the gas ionizes and an arc forms between the electrodes, shunting the surge current to ground. The SURGING SXH81-600X (often labeled GDTUBE2PIN 600V) is a two-terminal (2-pin) ceramic GDT rated for 600V DC nominal spark-over and a nominal impulse discharge current of 10 kA (8/20μs). It comes in a small cylindrical 8×6 mm through-hole package with axial leads. Once the surge passes and voltage falls below the tube’s re-strike voltage, it reverts to its high-impedance state, protecting downstream components from overvoltage damage.

How EstiSource Helps

EstiSource provides procurement engineers with a one-stop sourcing platform for parts like the SXH81-600X. We aggregate multiple vetted suppliers and real-time inventory for surge protection components, so buyers can compare prices, lead times, and certifications at a glance. Through RFQ and BOM tools, EstiSource delivers transparent quotations (showing quantity discounts) and supply-chain details – eliminating guesswork. Our system also tracks quality (e.g. RoHS, test reports) and automates audits, ensuring the GDTs you purchase meet spec. For hard-to-find or high-risk components, EstiSource offers fast quoting and alternative sourcing suggestions to prevent line-down situations. In short, we simplify and secure the entire buying process for circuit protection parts.

Why Choose EstiSource for Sourcing

For Buyers: EstiSource saves time and cost. You gain instant access to global suppliers of GDTs (and tens of millions of other parts), without dealing with countless vendor outreach. Our interface flags the best quotes and comparable parts, while verifying supplier authenticity to avoid counterfeit parts. By aggregating volume pricing (as shown above) and delivery options, we ensure you get competitive deals on items like SXH81-600X. The platform’s BOM management and price-tracking tools help you forecast budgets and spot market trends, so you’re always informed. In essence, EstiSource turns a complex multi-supplier search into a streamlined, transparent process. For Suppliers: EstiSource connects you directly with buyers worldwide. Listing your surge-protection products (e.g. gas tubes, MOVs, TVS diodes) exposes them to engineers in need of quick quotes and secure procurement. We handle the RFQ workflow and offer analytics on demand, so you can demonstrate lead times and certifications proactively. Using EstiSource means tapping into new markets and building trust through verified partner profiles. Ultimately, it simplifies selling: you spend less on marketing and more on serving customers who already have your parts on their BOMs.

1. Material Composition

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2. Manufacturing Process

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3. Challenges and Limitations

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Slow Turn-On Time

GDTs rely on gas ionization, so their response time is on the order of microseconds or longer. They are slower than semiconductor protectors (TVS diodes) and can let the voltage overshoot some before clamping.

Non-Linear & Unstable Threshold

Breakdown voltage can drift with temperature, aging, or repeated surges. Large tolerances (±20%) and light/UV sensitivity mean exact clamping voltage is not tightly controlled.

Not for Primary AC Protection

Standard two-terminal GDTs like SXH81-600X are designed for DC or low-frequency AC lines. They cannot safely conduct continuous AC mains current (especially above ~1000 V AC) without special grounding or series resistance. They are typically used as secondary protectors (after an MOV or transformer).

Footprint and Installation

GDTs are larger and heavier than SMD surge components, requiring space and careful board layout (creepage and clearance). The SXH81-600X’s body is only 8×6 mm, but its leads and standoff add volume compared to flat varistors.

Finite Life

Each high-energy surge puts stress on the gas tube. After many impulses, gas purity or electrode surfaces can degrade, raising breakdown voltage. Designs account for this (often thousands of strikes) but end-users should consider replacement after severe surge events.

Poor Voltage Regulation

Once triggered, a GDT offers very low impedance but not a precise clamp voltage. The tube “crowbars” the voltage down to its arc sustaining level, which can still be hundreds of volts above normal operating levels. Additional components (series resistors, parallel diodes) are often used to improve regulation.

UV/Light Sensitivity

GDTs can exhibit “photo-conduction” where exposure to bright light or UV can prematurely trigger breakdown. In practice, they are kept in opaque packages or on PCBs to mitigate this effect.

4. Costing

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Material Costs: The primary raw materials (alumina ceramic, metal alloys, and inert gases) are relatively inexpensive commodity substances. The ceramic tube and metal electrodes form the bulk of material cost, typically only a few cents per unit in high volume.

Processing & Assembly: The specialized manufacturing (clean ceramic processing, vacuum filling, brazing) adds moderate assembly cost. However, GDTs benefit from mature high-volume production. Tooling costs are amortized over large batches, so per-unit labor and equipment costs are low.

Economies of Scale: At small volumes, per-piece cost is higher due to fixed setup. As quantities increase, unit cost drops significantly. For example, supply listings show SXH81-600X at roughly $0.18 each for 5–9 pcs, falling to ~$0.10 or less at thousands of pcs.

Distributor Pricing: Online component vendors quote pricing tiers for this part. LCSC shows ~$0.18 per tube at 5pcs, $0.14 at 200pcs, and as low as $0.09 at 2500pcs. Similar ordering price-breaks appear on other platforms (e.g. $0.16 at qty 5, $0.09 at 2500 on China Electron’s site).

Volume Breakdown: Roughly estimating, raw materials + packaging might be ~$0.02–0.05 per tube, processing ~$0.01–0.02, and margin/overhead the rest. In large-scale production, the total landed cost is on the order of $0.05–$0.10 each.

Comparison: GDTs tend to cost less per device than high-end TVS diodes of equivalent energy rating, but more than simple MOV disks. The specific SXH81-600X is a standard catalog item, so prices remain quite low for buyers even with quality assurance included.

Price Factors: Custom requirements (e.g. special gas mix, tighter tolerance, UL recognition) could raise costs. Standard ratings (600V, 10kA) at RoHS-compliant materials keep the SXH81-600X at commodity pricing levels.

5. Properties and Characteristics

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Nominal Spark-Over Voltage: 600 V DC (with ±20% tolerance) – the voltage at which the tube breaks down under DC conditions.

Impulse Breakdown (Clamping) Voltage: Typically ~900–1100 V for an 8/20µs pulse, after which the arc forms. (The LCSC spec lists a “Rated Voltage” of 900 V and “Max Discharge Voltage” ~1100 V for SXH81-600X.)

Nominal Impulse Discharge Current: 10 kA peak (8/20µs waveform) – the standard surge current rating. Test current waveform is typically 8μs rise / 20μs decay, repeated per spec (10 pulses @ 1 min interval).

Peak Power: ~15 kA (likely referring to short 10/1000µs pulses or single event capability).

Response Time: Triggering occurs in the microsecond range (often <1 µs once breakdown is reached) – very fast compared to MOVs, though slower than semiconductor TVS devices.

Inter-Electrode Capacitance: ≈1.5 pF at 1 MHz. This very low capacitance means minimal loading of high-frequency or signal circuits. (Most GDTs stay below 2 pF.)

Off-State Impedance: Very high insulation resistance, generally >10⁹ Ω (1 GΩ) at applied voltages below breakdown. Leakage current is typically in nanoamp or picoamp range until triggering.

Number of Poles: 2 (two-terminal device, no ground pin). Both leads are equivalent; the tube is non-polar.

Operating Voltage: Rated for 600 V DC continuous. (Max stand-off DC is ~600 V; any significantly higher continuous voltage risks self-trigger.) Not designed for continuous AC above about 1000 VAC.

Operating Temperature: –30 °C to +85 °C. Performance drifts outside this range; use in ambient and board temperatures within specs.

Packaging: Axial lead, DIP style – cylindrical ceramic body 8 mm length × 6 mm diameter, with lead spacing suitable for 0.3″ (7.62 mm) boards.

Mechanical: Rigid leads solderable by standard methods (do not exceed ~300 °C for 10 s). Ceramic tube withstands shock and vibration well.

Certifications: RoHS-compliant materials noted. (No major agencies listed, but many GDTs meet IEC 61643-311 for surge arresters.)

Lifetime: Typically rated for thousands of impulse strikes (8/20µs) without damage. Precise life depends on surge severity. Manufacturers often specify a minimum impulse life test (e.g. 1000 pulses).

Creepage/Clearance: Maintain at least 3 mm clearance between the two leads on PCB, as suggested.

Other: Does not require polarity; no DC resistance or voltage drop until triggering. When latched, it will conduct until the voltage falls below the extinguishing level.

6. Frequently Asked Questions

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Q: What is a gas discharge tube (GDT) and how does SXH81-600X work?

A: A GDT is a surge arrester that uses a gas-filled gap to absorb high-voltage spikes. Under normal voltage it is non-conducting; when the voltage exceeds ~600 V DC (the SXH81-600X’s rating), the gas ionizes and an arc forms between the electrodes, shunting the surge current to ground. Once the surge passes and voltage falls below the tube’s re-strike voltage, it reverts to its high-impedance state. This protects downstream components from overvoltage damage.

Q: Why choose a GDT instead of a TVS diode or MOV?

A: GDTs like the SXH81-600X excel at handling very high surge currents (tens of kA) and have extremely low capacitance. They clamp large energy transients (e.g. lightning pulses) more robustly than TVS diodes. However, they switch on slightly slower and at a higher voltage than a TVS. In practice, GDTs are often used as first-line protectors in series with a faster clamp (TVS/MOV) to cover all surge scenarios.

Q: In what applications is the SXH81-600X commonly used?

A: This GDT is used in DC power distribution, telecom/data lines, renewable-energy and industrial systems, and automotive electronics. Anywhere a circuit needs protection from high-energy surges up to ~600 V DC, a GDT can be placed to divert spikes. For example, it may protect the input of an inverter, a telecom line card, or street-lighting control circuits. (Note: it is generally used in DC or isolated circuits; it’s not suitable as a primary clamp on 50/60Hz AC mains above ~1 kV.)

Q: What do “2-pin” and “±20% tolerance” mean for this part?

A: “2-pin” means there are two equivalent leads (electrodes) for the gas tube – no ground pin or polarity. You simply place it between two conductors (e.g. line-to-line or line-to-ground). The “±20%” tolerance indicates that the actual breakdown voltage can vary by that amount from 600 V (i.e. 480–720 V typically). This is normal for GDTs; designers should allow margin by pairing with other protection.

Q: How does temperature or environment affect the SXH81-600X?

A: It operates from –30 °C to +85 °C. Higher ambient or board temperatures can lower the breakdown voltage slightly and shorten life. Also avoid moisture and contaminants, as these could reduce insulation. The part should be mounted in open air (not conformal-coated) because a trapped surge event generates a transient arc.

Q: How long does a gas tube last, and can it fail?

A: A gas discharge tube is rated for many surge events (often thousands) before performance degrades. After repeated strikes, the gas can become less pure or the electrodes can be damaged, which raises the trigger voltage. Good practice is to replace the GDT if it has clamped an unusually large number of lightning pulses, or if its characteristics drift out of spec.

Q: Is the SXH81-600X polarized?

A: No. This GDT is non-polar – you can swap the two leads without changing behavior. It will clamp equally in either polarity of transient (though it’s typically used for positive or negative surges above 600 V).

Q: How should I install this GDT on a PCB?

A: Solder the axial leads in a through-hole pattern with ≥3 mm lead spacing. Use a short loop height to meet the thermal spec (≤300 °C for 10 s). Ensure clearances adhere to voltage. Often it is placed as close as possible to the surge source (e.g. input connector).

GDTUBE2PIN 600 V