ATC Semitec Ltd
ATC Semitec supply NTC thermistors from the world's most innovative NTC thermistor manufacturers. Many of our unique designs have now become industry standards and set the pace that others try to follow. 1% tolerance NTCs are standard and a wide degree of physical inter-changeability means your product design is not limited by mechanical constraints.
Our various NTC formats include SMD, flexible, epoxy coated, glass coated, DO-35 diode types, radial style and thin film versions.
PTCs as Resettable Fuses
Ceramic PTC thermistors can be used as re-settable fuses. Over-voltage and over-current conditions can cause the PTC to "switch" from a low resistance into a high resistance state. This limits the through current and thus protects the circuit or load in series with the PTC thermistor.
PTCs as Thermal Switches - Motor Protection
By varying the chemical composition of its ceramic material, the Curie point of a PTC thermistor can be altered to create a range of "trip" temperatures from 40°C to 190°C. The PTC's resistance increases dramatically after it reaches its Curie point and this increase can readily be used to "trip" an electronic circuit.
These PTCs are available in a radial format or can be supplied with flexible leads as motor protection ptcs or in ring terminals to help monitor the temperature of heat-sinks or power components.
PTCs as Self-Regulating Heaters
By applying a voltage across a PTC thermistor, current will flow and begin to heat the PTC. The PTC element rises in temperature until it reaches its Curie point, when its resistance will start to rise dramatically. The increase in PTC resistance limits the through current until the PTC heater reaches a state of equilibrium. If heat is withdrawn from the PTC, its resistance will drop allowing more current to flow through the PTC until equilibrium is again reached. Conversely, if the PTC element temperature rises, its resistance will increase reducing the through current until a state of equilibrium is again achieved.
Thus a PTC thermistor can operate as a self-regulating heater.
PEPI thermostats and thermal cutouts can offer accurate temperature control or over-temperature protection from 5°C to 200°C. With tolerances of ±3K and differentials as small as 10K (or even smaller in the creep-action designs) a PEPI thermostat offers the best control/cost ratio available anywhere.
Thermal protection and current protection is provided by a wide variety of PEPI designs with some of the smallest safety cut-outs available in the world. The latest model FCP also offers combined thermal cutout/current protection and despite its size, can switch up to 8A/250VAC.
Thermal Fuses supplied by NEC Schott and PEPI - A thermal fuse (or thermal cut-off) is a "one-shot", non-resettable, temperature-sensitive device that provides ultimate temperature protection in safety critical circuits. They are mainly defined by their temperature setting but also by the current rating, which is the maximum continuous current that can be applied.
NEC SEFUSE Range
The NEC Schott range of SEFUSE thermal fuses is one of the best established available offering a wide range of temperature and current ratings; from 70-240°C and upto 15A/250VAC. The SEFUSE range carries all the major approvals such as BEAB, UL, CSA, VDE (to the latest IEC/EN standards) assisting your own product approval accordingly.
ATC Semitec thermistor sensors come in all shapes and sizes. From simple plastic encapsulations for air-sensing applications to sophisticated leaf-spring designs, offering precision control of surface temperatures upto 250°C. Fast response sensors utilising exposed bead NTCs or thin wall tubes, help control rapidly changing temperatures in air or fluids upto 200ºC.
Single-insulated and double-insulated TPE encapsulated insertion probes using 0.5% tolerance NTCs ensure accurate control to +/-0.15K. These probes are waterproof to IP68 and are available with/without terminals to suit your application needs. We also supply brass, copper or stainless steel housings (with/without fixings) to give robust sensors that can be used in numerous environmental conditions.
Semifuse PTCs are resettable current fuses based on conductive polymer PTC technology. The PTC fuse will happily carry its rated "hold" current value until it is exceeded. If over-current occurs, the PTC resistance increases dramatically to limit the through current to safe levels.
The PTC will remain in this "off" state until the applied voltage is removed and the PTC has cooled down. The Semifuse PTC then "resets" to its pre-fault level ready to protect again.
Semifuse PTC fuses are available in a wide range of current values, voltages and formats. So whether you need a low-profile "strap", through-hole pcb or SMD design, Semifuse is all you need.