SMT100-35

SMT100 ELECTRICAL CHARACTERISTICS 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. Resetting of the device to the non-conducting state is 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. As with the avalanche T.V.S. device, if the SMT100 is subjected 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 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. 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. 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). SELECTING A SMT100 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 IBO IH IRM VRM VBR VBO VR V Ipp I COMPLIES WITH THE FOLLOWING STANDARDS PEAK SURGE VOLTAGE (V) VOLTAGE WAVEFORM (µS) 10/700 10/700 10/700 1.2/50 10/700 1.2/500 10/160 10/560 9/720 2/10 10/1000 2/10 0.5/700 CURRENT WAVEFORM (µS) 5/310 5/310 5/310 1/20 5/310 8/20 10/160 10/560 5/320 2/10 10/1000 2/10 0.8/310 ADMISSIBLE IPP NECESSARY RESISTOR (A) 25 38 50 50 50 100 75 55 25 150 50 150 25 12.5 6.5 11.5 10 11.5 - (CCITT) ITU-K20 (CCITT) ITU-K17 VDE0433 VDE0878 IEC-1000-4-5 FCC Part 68, lightning surge type A FCC Part 68, lightning surge type B Bellcore TR-NWT-001089 first level Bellcore TR-NWT-001089 second level CNET I31-24 1000 1500 2000 2000 level 3 level 4 1500 800 1000 2500 1000 5000 1000 w w w. l i t t e l f u s e . c o m 51 SMT100 ELECTRICAL CHARACTERISTICS (Tamb 25°C) SYMBOL V RM I RM VR V BR C PARAMETER Stand-off Voltage Leakage Current at Stand-off Voltage Continuous Reverse Voltage Breakdown Voltage Capacitance SYMBOL V RO IH I BO I PP IR PARAMETER Breakover Voltage Holding current Breakover Current Peak pulse Current Continuous Reverse Current THERMAL RESISTANCE SYMBOL RTH (J-I) RTH (J-I) PARAMETER Junction to leads Junction to ambient on printed circuit (with standard footprint dimensions) VALUE 20 100 UNIT °C/W °C/W ABSOLUTE MAXIMUM RATINGS (Tamb 25°C) SYMBOL I PP PARAMETER Peak pulse Current: 10/1000µS (open circuit voltage waveform 1kV 10/1000µS) 5/310µS (open circuit voltage waveform 4kV 10/700µS) 8/20µS (open circuit voltage waveform 4kV 1.2/50µS) 2/10µS (open circuit voltage waveform 2.5kV 2/10µS) I TSM Non-repetitive surge peak on-state current F = 50Hz Non-repetitive surge peak on-state current F = 50Hz TL Tstg Tj Maximum lead temperature range Storage temperature range Maximum junction temperature 50Hz 60Hz 0.2s 2s 100 150 250 500 55 60 25 12 260 -55 to +150 150 A A A A A A A A VALUE UNIT °C °C °C Type Marking IRM @ VRM MAX (µA) 2 2 2 2 2 2 2 (V) 32 55 110 120 170 200 230 IRM @ VR MAX (µA) 50 50 50 50 50 50 50 (V) 35 65 120 140 200 230 270 VBO @ IBO MAX (V) 55 80 160 200 265 300 350 (mA) 800 800 800 800 800 800 800 IH MIN (Note 1) C MAX (pF) 180 160 140 140 130 120 120 Laser SMT100-35 SMT100-65 SMT100-120 SMT100-140 SMT100-200 SMT100-230 SMT100-270 B035 B065 B120 B140 B200 B230 B270 (mA) 150 150 150 150 150 150 150 Note 1: Measured @ 1V bias, 1MHZ. All parameters are tested using a FET TEST model 3600. TM 52 w w w. l i t t e l f u s e . c o m SMT100 w w w. l i t t e l f u s e . c o m 53