Thyristors - Application Notes
FEATURES
Protects by Limiting voltages and shunting surge currents away from sensitive circuits.
Designed for telecommunications applications such as line cards, modems, PBX, FAX, LAN, VHDSL.
Helps meet standards such as GR1089, ITU K.20, IEC950, UL1459&50, FCC part 68.
Low capacitance, High surge (A, B, C rating available), precise voltage limiting, Long life.
SELECTION GUIDE
Follow these steps to select the proper Thyristor surge protector for your application:
1. Define the operating parameters for the circuit:
Ambient operating temperature range
Maximum telephone line operating current (highest battery and shortest copper loop)
Maximum operating voltage: (Maximum DC bias + peak ringing voltage)
Maximum surge current
System voltage damage threshold
2. Select device with an off-state voltage rating (VDRM) above the maximum operating voltage at the minimum
operating temperature
3. Select surge current ratings (IPPS and ITSM) > those which the application must withstand
4. Verify that the minimum holding current of the device at the maximum ambient temperature is above the maximum
dc current of the system
5. Verify that the maximum breakover voltage of the device is below the system damage threshold.
6. Verify that the circuit's ambient operating temperatures are within the device's operating temperature range.
7. Verify that the device's dimensions fit the application's space considerations.
8. Independently evaluate and test the suitability and performance of the device in the application
MAXIMUM THERMAL RATINGS
Rating Symbol Value Unit
Storage Junction Temperature Range TSTG
-50 to 150 °C
Operating Junction Temperature Range TJ-40 to 150 °C
Operating Ambient Temperature Range TA -40 to 65 °C
Notes:
PCB board mounted on minimum foot print.
THERMAL CHARACTERISTICS
Characteristic Symbol Value Unit
Thermal Resistance Junction to leads TL on tab adjacent to plastic.
Both leads soldered to identical pad sizes. RØJL Max. 20 °C / W
Notes:
The junction to lead thermal resistance represents a minimum limiting value with both leads
soldered to a large near-infinite heatsink. The junction to ambient thermal resistance depends
strongly on board mounting conditions and typically is 3 to 6 times higher than the junction to
lead resistance. The data shown is to be used as guideline values for preliminary engineering.