From soft-start and snubber circuits to dynamic braking and RF dummy loads, non-inductive bulk ceramic resistors have a wide range of applications, such as: radar, motor drives, broadcast transmitters, RF amplifiers, semiconductor process equipment, high voltage power supplies, switchgear, X-ray, lasers, medical defibrillators, and energy research. Electronic systems often require rugged resistors that perform reliably under conditions of high voltage, current, or energy.
Pulse, pre-charge and soft-start
The compact pulse energy capability of ceramics allows flexible design without sacrificing power. Ceramic resistors can obtain greater power dissipation in one third of the footprint of wire-wound resistors, delivering excellent performance where high peak power or high-energy pulses must be handled in small and efficient spaces.
Resistor technology comparison
|Geometry size||Complex packaging||Flexible||Flexible|
|Power range||5 W to 1 kW||1 W to 1 kW||1 W to 1 kW|
High voltage continuous and pulse applications can be addressed with ceramic resistors, including include crowbars, capacitor charging or discharging, and high voltage power supply protection circuits. Bulk ceramic resistors can provide low inductance, high average power per unit size, stability at high voltage, and durability at extreme peak-power levels.
When a spike in voltage occurs from electrical switching, an RC snubber circuit is typically used to suppress the discharges and protect the circuit. However, a wire wound or film resistor may not hold up to the high voltage, current or energy conditions. The power spike can result in megawatts of instantaneous peak power which could cause a small mass of film or wire-wound resistors to degrade and even fail.
Bulk ceramic resistors are used extensively for high-frequency loads in broadcast and communication equipment because of their non-inductive characteristics. They provide excellent non-inductive power-handling capacity at frequencies into the GHz range, with no sacrifice in power dissipation. In advanced digital applications such as digital radio and HDTV transmitters involving pulses at high frequencies, the small size, flexibility and overload reliability of ceramic resistors are ideal.
High energy may be desired in a testing situation, from addressing minor circuit spikes to the diverting a lightning strike. In the case of power generators, test loads allow for a low-risk verification of a unit’s capabilities.