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PTC
(Positive Temperature Coefficient) Thermistors have
resistance-temperature characteristic that exhibit a
very small negative temperature coefficient until the
device reaches a critical temperature that is referred
to as “Curie’’ temperature
or Transition temperature. Above the curie temperature,
the devices exhibit sharp rise in resistance. |
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PTC
Thermistor Terminology |
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Zero
- Power resistance value - The Zero-power resistance
is the measured resistance value of the PTC at
250C, with no appreciable self-heat producing
current flowing through the Thermistor. |
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Transition
Temperature (Ttr) - The Transition temperature
or switching temperature is the temperature at
which the resistance of the PTC Thermistor begins
to rise sharply and it is the temperature at which
the resistance of the PTC becomes twice the minimum
resistance value. |
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Switching
or Tripping current at 250C - It is the minimum
amount of current required by the PTC to guarantee
switching at 250C. |
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Non-switching
or non-tripping current at 250C - It is the maximum
amount of current the PTC must be able to pass
without switching at 250C. |
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Switching
/ Tripping Time - It is the time required for
switching the devices, while passing the switching
current at 250C. |
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