2CL82 Fast Recovery High Voltage Diode 30KV 5mA 80nS

30 kV Blocking in a Single Axial Body

Every multiplier stage reaches a point where reverse voltage, rather than current, decides how many parts the stack needs. 30 kV is the top of the 2CL axial range, and it changes the arithmetic of a cascade. Where a lower step would put an extra high voltage diode into every stage, one 2CL82 can hold a whole stage voltage by itself — fewer joints to insulate, shorter assemblies, and fewer surfaces across which tracking can start. The trade is on the data sheet rather than buried in it. Every figure in the table below carries its test condition, which is what a design review will ask about.

Construction Detail Behind the Voltage Rating

• Axial leads at both ends. The diode sits through a board, a bracket or a stack plate without a socket, and the lead itself carries the connection — something you can form, sleeve or pot once it is in place.
• High thermal conductivity epoxy molding. The encapsulant does two jobs: it seals the junction from the surrounding medium and moves heat out of a chip that has almost no surface area of its own.
• Low internal resistance. In a multiplier the part conducts in short, high-current pulses, and any resistance inside the body turns into heat at exactly the wrong moment.
• Passivated chip surface, sealed before molding. The blocking junction is protected before the epoxy goes on, which keeps reverse leakage predictable instead of letting it drift with surface charge.
• Discharge behaviour. Stages that dump a capacitor through the diode rely on it recovering cleanly after the pulse, inside the 0.5 A surge rating.
• Banded cathode. A band near one end marks polarity, so orientation stays readable after potting and during a service call.
• Shared construction across the range. The 16 kV, 18 kV and 20 kV high voltage diodes in this series use the same axial leaded body and cathode marking, so mounting practice carries over when a design moves up or down a step.

Current, Forward Drop and Heat Path

Three figures set what this high voltage diode can and cannot do in a circuit. Average forward current is 5 mA, quoted for a 50 Hz half-sine wave into a resistive load with a break temperature of 50 °C — that is the continuous conduction budget, while pulses are covered separately by 0.5 A for 0.01 s. Forward peak voltage is ≥52.0 V, which at 5 mA works out to roughly a quarter of a watt generated inside the body. A quarter of a watt sounds small until you look at the volume it is generated in. There is no heatsink tab on an axial diode: heat leaves through the two leads and into whatever they are soldered or clamped to. Short leads into a metal bracket, a cooled plate or a filled compound run cooler than long leads hanging in still air inside a sealed enclosure. On a continuously running assembly, treat the leads as part of the thermal design rather than as pure electrical connections. Leakage is the other figure to carry into the design. At the rated reverse voltage the published limits are 2.0 µA at 25 °C and 20 µA at 100 °C. The warmer number is the one that matters inside a sealed tank, because reverse current grows with temperature and adds to the load the stage has to supply; measure and specify it at the temperature the equipment actually reaches.

Assembly and Insulation Practice

1. Choose the insulating medium before the layout. Oil or insulating gas is the recommended environment at this voltage class, because the medium shares the insulation duty with the package and helps carry heat off the leads.
2. Clean and dry the body, the leads and the surrounding hardware. At 30 kV a fingerprint or a flux smear across the epoxy is a leakage path, and it shows up long before the chip does.
3. Set clearances for the medium you are using, not for the part alone. Creepage across a surface is a different problem from clearance through oil or gas, and both need room around a body this size.
4. Form leads a few millimetres away from the epoxy shoulder and support the lead while you bend it; a bend pressed against the body seal puts mechanical stress exactly where the insulation is thinnest.
5. Solder with a controlled iron and a short dwell, and clamp or heat-shunt the lead between the joint and the body when the process runs hot.
6. If the diode has to run in air, fit insulated electrodes at both ends and add forced cooling — still air removes very little heat from two thin leads, and a small body discharges easily across a gap.
7. Pot or encapsulate with a degassed compound, cured to its supplier's schedule, and keep the coating even around both leads so no void forms at the body surface.
8. Run a partial-discharge or leakage check at working voltage on the finished assembly and record the reading, so later service work has a baseline.

Circuits That Suit a 30 kV Device

• Multiplier cascades in imaging generators. Cockcroft–Walton and similar ladders inside X-ray, DR, CT and dental panoramic tanks, where a 30 kV device can hold a full stage and keep the ladder short.
• Rectifier chains in oil-filled tanks. Stages running at tens of kilovolts and a few milliamps — the working territory of axial high voltage diodes, where holding voltage matters far more than passing current.
• Accelerator and radar supplies. Bias and rectifier chains in electron accelerator and radar power units, built around kilovolt rails and small standing currents.
• Non-destructive testing and DC high-voltage test sets. Portable X-ray inspection units and HV test transformers that need a predictable blocking part in a small axial package.
• Pulse discharge networks. Capacitor discharge circuits that depend on clean recovery after each pulse rather than on continuous conduction.
• Field replacement. Equipment already in service where the original 30 kV axial part has failed; cross-reference the banded end, the lead spacing and the ratings rather than the part number, since numbering schemes differ between high voltage diode manufacturers.

2CL82 Ratings and Test Conditions

Potting Compounds for Sealed Assemblies

Ordering Notes and Delivery

Send the insulating medium, the working peak reverse voltage of the stage, the average current it draws and the number of parts per build, and the right voltage step can be confirmed in one reply. Orders leave by international express. The data sheet and the package drawing can travel with the quotation and are worth filing with incoming inspection, because a rating only means something next to its test conditions. If you are weighing this part against offers from other high voltage diode manufacturers, check that reverse leakage is quoted at the same temperature and the same reverse voltage — figures taken on different test bases cannot be compared. Builds that use more than one voltage step from this series should keep each step on its own line item and its own bin, since mixing them is the usual way a wrong part ends up in a stack.

Technical Support & Model Matching

Selection starts with your circuit, not a catalogue number: tell us the working voltage, load current, switching frequency and ambient cooling conditions, and our engineers will match a model from our range and explain the margin left in the design. Each model ships with its datasheet, package drawing and installation guide, and we stay available for mounting and soldering questions, start-up checks and fault finding when an existing part runs hot or fails early. Orders run from about 7 days to 6 months depending on quantity, usually by international express.

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