Overcurrent Circuit Protection: Fuse vs. PTC
Overcurrent Protection Applications
The PTC material is supplied in both a radial leaded package as well as a surface mount type. The function of the resettable PTC has many design applications.
SCSI Plug and Play applications include both the mother-board and the many peripherals that can be frequently connected to and disconnected from the computer ports. The mouse, keyboard, printer, modem and monitor ports represent opportunities for a faulty unit or damaged cable to be connected and also possible misconnections. The ability to reset after correction of the fault is particularly attractive. Some of these applications use radial leaded while surface mount units are more appropriate for others.
Disk drive protection can be supplied by a PTC from the potentially damaging overcurrents resulting from excessive voltage from a power supply malfunction. Disk drive applications tend to use the surface mount PTC.
Power supplies are vulnerable to malfunctions in the circuits the power is being supplied to. Without protection the power supply will attempt to provide the current required by a low resistance fault. Individual PTCs can be used to protect each load where there are multiple loads or circuits. Typically the device is placed in the output circuit and can be either radial leaded or surface mount.
Motor overcurrents can produce excessive heat that may damage the winding insulation and for small motors may even cause a failure of the very small diameter wire windings. The PTC will generally not trip under normal start up currents. Motors are commonly protected by radial leaded PTCs.
Transformers can be damaged by overcurrents due to circuit faults and the current limiting function of a PTC can provide protection. The PTC is located on the load side of the transformer to minimize the effect of circuit faults. Various applications use either the radial leaded or surface mount units.
The PTC material is supplied in both a radial leaded package as well as a surface mount type. The function of the resettable PTC has many design applications.
SCSI Plug and Play applications include both the mother-board and the many peripherals that can be frequently connected to and disconnected from the computer ports. The mouse, keyboard, printer, modem and monitor ports represent opportunities for a faulty unit or damaged cable to be connected and also possible misconnections. The ability to reset after correction of the fault is particularly attractive. Some of these applications use radial leaded while surface mount units are more appropriate for others.
Disk drive protection can be supplied by a PTC from the potentially damaging overcurrents resulting from excessive voltage from a power supply malfunction. Disk drive applications tend to use the surface mount PTC.
Power supplies are vulnerable to malfunctions in the circuits the power is being supplied to. Without protection the power supply will attempt to provide the current required by a low resistance fault. Individual PTCs can be used to protect each load where there are multiple loads or circuits. Typically the device is placed in the output circuit and can be either radial leaded or surface mount.
Motor overcurrents can produce excessive heat that may damage the winding insulation and for small motors may even cause a failure of the very small diameter wire windings. The PTC will generally not trip under normal start up currents. Motors are commonly protected by radial leaded PTCs.
Transformers can be damaged by overcurrents due to circuit faults and the current limiting function of a PTC can provide protection. The PTC is located on the load side of the transformer to minimize the effect of circuit faults. Various applications use either the radial leaded or surface mount units.
