TR250-145U Tyco Electronics, TR250-145U Datasheet - Page 2

• Manufacturer Part Number: TR250-145U
• Description: POLYSWITCH 0.145A HOLD UNENCAPS
• Manufacturer: Tyco Electronics
• Series: PolySwitch®r

Specifications of TR250-145U

• R Min/max: 3.500 ~ 6.500 Ohm
• Voltage - Max: 60V
• Time To Trip: 2s
• Current - Hold (ih) (max): 145mA
• Current - Trip (it): 290mA
• Current - Max: 3A
• Package / Case: Radial
• Holding Current: 0.145A
• Tripping Current: 0.29A
• Initial Resistance Max: 6.5ohm
• Initial Resistance Min: 3.5ohm
• Resistance R1: 12ohm
• Peak Reflow Compatible (260 C): No
• Fuse Terminals: Radial Leaded
• Thermistor Type: PTC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: TR145U

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Selection Table for Telecommunications and Networking Devices
PolySwitch Telecommunications and Networking Resettable Devices
Step 1.
Use the selection guide to narrow your product selection based on key
device characteristics.
Step 2.
Look across the top of the thermal derating table T2 on page 306 to
find the temperature that most closely matches the circuit’s maximum
operating temperature. Look down that column to find the value equal
to or greater than the circuit’s normal operating current. Now look to the
far left of that row to find the part number for the PolySwitch telecom-
munications device that will best accommodate the circuit.
Note: The thermal derating curves in Figure T1 on page 307 are the
normalized representations of the data in the thermal derating table.
Step 3.
Time-to-trip is the amount of time it takes for a device to switch to a
high resistance state once a fault current has been applied across the
device. Identifying the PolySwitch device’s time-to-trip is important in
order to provide the desired protection capabilities. If the device you
choose trips too fast, undesired or nuisance tripping will occur. If the
device trips too slowly, the components being protected may be
damaged before the device switches to a high resistance state.
Refer to typical time-to-trip curves (Figures T12-17) on pages 313-315
for each of the PolySwitch devices. If the PolySwitch device’s time-to-
trip is too fast or too slow for the circuit, go back to Step 2 and choose
an alternate device.
Step 4.
Ensure that your application’s minimum and maximum ambient
temperatures are within the operating temperature range of -40°C
to 85°C.
Step 5.
PolySwitch devices assist your telecommunications equipment in meet-
ing agency requirements. To confirm your selection, independently
evaluate and test the device to the application requirements.
Review the Protection Application Guide on page 303
which is based on the agency specification required to
qualify the final equipment.
Verify that the PolySwitch device hold current will accom-
modate the telecommunications circuit’s maximum ambi-
ent temperature and normal operating current.
Verify that the time-to-trip characteristic of the chosen
device meets the protection requirements of the
telecommunications equipment circuit.
Verify ambient operating condition.
Independently evaluate and test the device.
Raychem Circuit Protection