Key Selection Information
| Selection Parameter | Confirmed Information |
|---|---|
| Protection type | 2-electrode gas discharge tube |
| Typical DC breakdown | 75 V at 100 V/s |
| DC breakdown range | 52 V to 98 V |
| Impulse breakdown | 500 V max at 100 V/µs; 650 V max at 1 kV/µs |
| Capacitance | <1 pF at 1 MHz |
| Insulation resistance | >1 GΩ at 50 VDC |
| Nominal impulse discharge current | 2 kA, 8/20 µs, 10 pulses |
| SMD dimensions | 4.5 × 3.2 × 2.7 mm |
Product Overview
The SG75 is a Littelfuse surface-mount two-electrode gas discharge tube with a 75 V typical DC breakdown rating. Its low capacitance and compact 4.5 × 3.2 × 2.7 mm SMD body make it suitable for surge protection on broadband or communication lines where a conventional protection element could add excessive signal loading.
The exact SG75 row specifies a 52 V minimum, 75 V typical and 98 V maximum DC breakdown range at 100 V/s. Under faster transients, the maximum impulse breakdown rises to 500 V at 100 V/µs and 650 V at 1 kV/µs, so system protection should be evaluated from the dynamic limits rather than only the 75 V nominal value.
Technical Specifications
| Parameter | Confirmed Information |
|---|---|
| DC breakdown at 100 V/s | 52 V min, 75 V typ, 98 V max |
| Impulse breakdown at 100 V/µs | 500 V maximum |
| Impulse breakdown at 1 kV/µs | 650 V maximum |
| Insulation resistance | >1 GΩ at 50 VDC |
| Capacitance | <1 pF at 1 MHz |
| Arc voltage | Approximately 10 V |
| Glow-to-arc transition current | Approximately 1.0 A |
| Glow voltage | Approximately 60 V |
| Nominal AC discharge current | 2 A, 10 operations at 50 Hz |
| Nominal impulse discharge current | 2 kA, 10 operations at 8/20 µs |
| SMD dimensions | 4.5 × 3.2 × 2.7 mm |
| Operating/storage temperature | -40°C to +90°C |
Design Considerations
The 75 V typical DC breakdown value should be coordinated with the line’s maximum normal voltage, but fast-transient behavior is governed by the much higher impulse breakdown levels. Downstream semiconductors may still need a secondary clamp if they cannot tolerate the GDT’s transient let-through voltage.
Because the SG75 is a low-capacitance surge element, placement and PCB parasitics can matter in fast events. Keep the surge-current path short and low inductance so lead and trace inductance do not add unnecessary voltage on top of the device’s own impulse breakdown.
Related Engineering Resources
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