SMT100 LITTELFUSE | Alldatasheet
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Technical content
www.littelfuse.com The electrical characteristics of a SMT100 device are similar to that of a self-gated Triac, but the SMT100 is a two terminal device with no gate. The gate function is achieved by an internal current controlled mechanism. Like the T.V.S. diodes, the SMT100 has a standoff voltage (Vrm) which should be equal to or greater than the operating voltage of the system to be protected. At this voltage (Vrm) the current consumption of the SMT100 is negligible and will not affect the protected system. When a transient occurs, the voltage across the SMT100 will increase until the breakdown voltage (Vbr) is reached. At this point the device will operate in a similar way to a T.V.S. device and is in avalanche mode. The voltage of the transient will now be limited and will only increase by a few volts as the device diverts more current. As this transient current rises, a level of current through the device is reached (Ibo) which causes the device to switch to a fully conductive state such that the voltage across the device is now only a few volts (Vt). The voltage at which the device switched from the avalanche mode to the fully conductive state (Vt) is known as the Breakover voltage (Vbo). When the device is in the Vt state, high currents can be diverted without damage to the SMT100 due to the low voltage across the device, since the limiting factor in such devices is dissipated power (V x I). Resetting of the device to the non-conducting state is controlled by the current flowing through the device. When the current falls below a certain value, known as the Holding Current (Ih), the device resets automatically. As with the avalanche T.V.S. device, if the SMT100 is subjected to a surge current which is beyond its maximum rating, then the device will fail in short circuit mode, ensuring that the equipment is ultimately protected.
ELECTRICAL CHARACTERISTICS
COMPLIES WITH THE PEAK SURGE VOLTAGE CURRENT ADMISSIBLE IPP NECESSARY FOLLOWING STANDARDS VOLTAGE WAVEFORM WAVEFORM RESISTOR (V) ( µS) (µS) (A) (CCITT) ITU-K20 1000 10/700 5/310 25 - (CCITT) ITU-K17 1500 10/700 5/310 38 - -VDE0433 2000 10/700 5/310 50 VDE0878 2000 1.2/50 1/20 50 - IEC-1000-4-5 10/700 5/310 50 - level 4 1.2/500 8/20 100 - FCC Part 68, lightning surge 1500 10/160 10/160 75 12.5 type A 800 10/560 10/560 55 6.5 FCC Part 68, lightning surge 1000 9/720 5/320 25 - type B Bellcore TR-NWT-001089 2500 2/10 2/10 150 11.5 first level 1000 10/1000 10/1000 50 10 Bellcore TR-NWT-001089 5000 2/10 2/10 150 11.5 second level CNET I31-24 1000 0.5/700 0.8/310 25 - level 3 VR VBRVRM VBO IRM IBO IH Ipp I V 1. When selecting a SMT100 device, it is important that the Vrm of the device is equal to or greater than the the operating voltage of the system. 2. The minimum Holding Current (Ih) must be greater than the current the system is capable of delivering otherwise the device will remain conducting following a transient condition. V-I Graph illustrating symbols and terms for the SMT100 surge protection device SMT100
www.littelfuse.com SMT100 Note 1: Measured @ 1V bias, 1M HZ. All parameters are tested using a FET TEST TM model 3600. ELECTRICAL CHARACTERISTICS (Tamb 25°C) ABSOLUTE MAXIMUM RATINGS (Tamb 25°C) THERMAL RESISTANCE SYMBOL PARAMETER SYMBOL PARAMETER V RM Stand-off Voltage V RO Breakover Voltage I RM Leakage Current at Stand-off Voltage I H Holding current V R Continuous Reverse Voltage I BO Breakover Current V BR Breakdown Voltage I PP Peak pulse Current C Capacitance I R Continuous Reverse Current SYMBOL PARAMETER VALUE UNIT RTH (J-I) Junction to leads 20 °C/W RTH (J-I) Junction to ambient on printed circuit 100 °C/W (with standard footprint dimensions) SYMBOL PARAMETER VALUE UNIT I PP Peak pulse Current: 10/1000µS (open circuit voltage waveform 1kV 10/1000µS) 100 A 5/310µS (open circuit voltage waveform 4kV 10/700µS) 150 A 8/20µS (open circuit voltage waveform 4kV 1.2/50µS) 250 A 2/10µS (open circuit voltage waveform 2.5kV 2/10µS) 500 A I TSM Non-repetitive surge peak on-state current 50Hz 55 A F = 50Hz 60Hz 60 A Non-repetitive surge peak on-state current 0.2s 25 A F = 50Hz 2s 12 A TL Maximum lead temperature range 260 °C Tstg Storage temperature range -55 to +150 °C Tj Maximum junction temperature 150 °C Type SMT100-35 SMT100-65 SMT100-120 SMT100-140 SMT100-200 SMT100-230 SMT100-270 Marking Laser B035 B065 B120 B140 B200 B230 B270 IRM @ VRM MAX (µA) (V) IRM @ VR MAX (µA) (V) 120 140 200 230 270 800 800 800 800 800 800 800 160 200 265 300 350 110 120 170 200 230 VBO @ IBO MAX (V) (mA) IH MIN (Note 1) (mA) 150 150 150 150 150 150 150 C MAX (pF) 180 160 140 140 130 120 120
www.littelfuse.com SMT100