Vocabulary
·I hold = Hold current: maximum current device will pass without tripping in 23 still air. ℃
·I trip = Trip current: minimum current at which the device will trip in 23 still air. ℃
·V max = Maximum voltage device can withstand_without damage at rated current (I max )
·I max = Maximum fault current device can withstand_without damage at rated voltage (V max )
·P d typ. = Typical power dissipated from device when in the tripped state at 23℃ still air.
·R min = Minimum resistance of device in initial (un-soldered) state.
·R 1max = Maximum resistance of device at 23℃ measured one hour after tripping or reflow soldering of 260℃ for 20 sec.
■ Value specified is determined by using the PWB with 0.030”*1.5oz copper traces.
■ Caution: Operation beyond the specified rating may result in damage and_possible arcing and_flame.
■ Specifications are subject to change without notice.
Polymeric PTC Selecting Guide
■ Determine the following operating parameters for the circuits:
· Normal operating current (I hold ) · Maximum interrupt current (I max )
· Maximum circuit voltage (V max ) · Normal operating temperature surrounding device (min℃/max℃)
■ Select the device from factor and_dimension suitable for the application
■ Compare the maximum rating for V max and_I max of the PPTC device with the circuit in application and_make sure
the circuit’s requirement does not exceed the device rating.
■ Check that PPTC device’s trip time (time-to-trip) will protect the circuit.
■ Verify that the circuit operating temperature is within the PPTC device’s normal operating temperature range.
■ Verify that performance and_suitability of the chosen PPTC device in the application.
WARNING
■ Mechanical Stress
· PPTC devices will undergo a thermal expansion during fault condition. If PPTC devices are installed or placed in an application
where the space between PPTC devices and_the surrounding materials (e.g.， covering materials， packaging materials， encapsulate
materials and_the like) is insufficient， it will cause an inhibiting effect upon the thermal expansion. Pressing， twisting， bending and_
other kinds of mechanical stress will also adversely affect the performance of the PPTC devices， and_shall not be used or applied.
■ Chemical Pollutants
· Silicone-based oils， oils， solvents， gels， electrolytes， fuels， acids， and_the like will adversely affect the properties of PPTC devices，
and_shall not be used or applied.
■ Electronic and_Thermal Effect
· PPTC devices are secondary protection devices and_are used solely for sporadic， accidental over-current or over-temperature
error condition， and_shall NOT be used if or when constant or repeated fault conditions (such fault conditions may be caused by，
among others， incorrect pin-connection of a connector) or over-extensive trip events may occur.
· PPTC devices are different from fuses and， when a fault condition occurs， will go into high-resistance state and_do not open
circuit， in which case the voltage at such PPTC devices may reach a hazardous level.
· Operation over the maximum rating or other forms of improper use may cause failure， arcing， flame and/or other damage to
the PPTC devices.
· Conductive material contamination， such as metal particle， may induce shortage， flame or arcing.
· Due to the inductance， the operation circuits may generate a circuit voltage (Ldi/dt) above the rated voltage of PPTC devices，
which shall not be used under such circumstances.
■ General
· Customers shall evaluate and_test the properties of PPTC devices independently to verify and_ensure that their individual
applications will be met.
· The performance of PPTC devices will be adversely affected if they are improperly used under electronic， thermal and/or
mechanical procedures and/or conditions non-conformant to those recommended by manufacturer.
· Customers shall be responsible for determining whether it is necessary to have back-up， failsafe and/or fool-proof protection
To avoid or minimize damage that may result from extra-ordinary， irregular function or failure of PPTC devices.
· Any and_all responsibilities and_liabilities are disclaimed if any item under this notice of warning is not complied with.
