BEHLKE HV switches

Push-pull switches

The switch can generate truly symmetrical square wave pulses with fast rise and fall times, typically associated with capacitive loads. Compared to a single-switch setup, a push-pull circuit does not require resistors, resulting in greater energy efficiency at higher operating frequencies. Without the need for operational resistors, the size of the input storage capacitor can be minimized without negatively impacting the flatness of the pulse peaks. For applications requiring high standards of pulse shaping, the push-pull switch is an ideal choice for square wave pulses.

BEHLKE high-voltage switching modules are always electrically isolated and can be used as the high-voltage terminal for both positive and negative voltages. If the voltage polarity needs to change during operation (e.g., in TOF mass spectrometers with positive and negative ion acceleration), alternating current (AC) high-voltage switches should be considered. AC high-voltage switches can be configured as a single switch or a push-pull switch. BEHLKE switches can be controlled via a simple TTL signal, with internal control and safety circuits providing pulse shaping, overfrequency protection, and temperature protection.

All switches include optional cooling features such as enhanced thermal conductivity (Option ITC), non-conductive ceramic cooling surfaces (Option CCS), isolated copper cooling flanges (Option GCF), non-conductive ceramic cooling flanges (Option GCF-CER), or non-isolated heat sinks made of copper (Option CF) or lightweight graphite material (Option CF-GRA). For corona-critical applications, the heat sinks can also be made of non-conductive high-performance ceramic (Option CF-CER). When air cooling reaches its limits, liquid cooling should be utilized. Two liquid cooling methods are available: indirect liquid cooling (Option ILC) and direct liquid cooling (Option DLC). Indirect liquid cooling offers moderate cooling efficiency and is designed for simple conductive and non-conductive coolants, such as tap water or deionized water. More efficient and better suited for high-frequency operations is direct liquid cooling (Option DLC), which uses non-conductive coolants such as perfluoropolyether (PFPE), perfluorocarbon (PFC), or hydrofluoroether (HFE). Custom switches with tailored electrical and mechanical modifications can be made available upon request.

Fast High Voltage Diodes

Fast high-voltage diode assemblies for freewheeling purposes feature an 80 ns recovery time, designed to handle voltages up to 200 kV and peak currents up to 10 kA (Model Series FDA). FDA diode assemblies are available as single diodes, dual diodes, or diode networks with series blocking diodes, suitable for use with MOSFET or IGBT switches. All BEHLKE high-voltage diodes are offered with cost-effective plastic housings or the above cooling options. Refer to Product Group E. Custom high-voltage diodes are available upon request.

Instruction for model selection

High-voltage and pulsed power applications always carry a certain risk of sparking and electrical flashovers, especially when environmental conditions, operating conditions, or load conditions unexpectedly change. Therefore, the peak current capability of solid-state switches should always be as high as possible, at least higher than the potential short-circuit current. Regarding the selection of the rated voltage, we recommend that the safety margin for MOSFET switches be at least 5%, and for all bipolar switches (IGBT, MCT, SCR), the safety margin should be at least 20%, to minimize the risk of damage due to unexpected voltage fluctuations or reverse voltage spikes.

The long-term reliability and mean time between failures (MTBF) of high-voltage solid-state switches are always positively correlated with operating temperature. We strongly suggest operating switches at moderate temperatures whenever possible. This can be achieved by carefully selecting components such as on-state resistance, current capacity, intrinsic capacitance, and coupling capacitance. Please refer to our general guidelines for calculating resistive and capacitive power losses. If the calculated power dissipation exceeds the switch's Pd(max) rating, appropriate cooling options must be added.

Please note that individual Pd(max) ratings always refer to an ambient case temperature of 25°C. Designers must also take into account elevated ambient temperatures and the actual case temperature during operation. As a result, many applications require specialized cooling measures. BEHLKE offers a wide range of cooling options for various scenarios. Designers can choose among ceramic cooling surfaces, heat sinks, cooling flanges, or liquid cooling using water or dielectric coolants. For more information, please click on the product categories below or contact us directly.