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TYN1225 TO-220 SCR Thyristor 25A 1200V High-Power AC Switch (5-Pack)
TYN1225 TO-220 SCR Thyristor 25A 1200V High-Power AC Switch (5-Pack)
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TYN1225 TO-220 SCR Thyristor — 25A / 1200V High-Power AC Switch (5-Pack)
The TYN1225 is a high-power SCR (Silicon Controlled Rectifier) thyristor from STMicroelectronics in a TO-220 through-hole package, rated at 25A RMS and 1200V blocking voltage. With a low gate trigger current of just 15mA, it is ideal for AC motor speed control, phase-angle power control, and soft-start circuits in industrial and consumer applications.
Key Specifications
| Parameter | Value |
|---|---|
| Part Number | TYN1225 |
| Package | TO-220 (through-hole) |
| RMS On-State Current (IT) | 25A |
| Peak Repetitive Voltage (VDRM) | 1200V |
| Gate Trigger Current (IGT) | 15mA max |
| Gate Trigger Voltage (VGT) | 1.5V max |
| Holding Current (IH) | 30mA typical |
| On-State Voltage (VT) | 1.55V @ 25A |
| Turn-Off Time (tq) | ~100μs |
| Operating Temperature | −40°C to +125°C |
| Quantity | 5 pieces |
SCR vs TRIAC — When to Use SCR
| Feature | SCR (TYN1225) | TRIAC (BTA12-600C) |
|---|---|---|
| Conduction | Half-wave (one direction) | Full-wave (both directions) |
| AC Control | Requires 2 SCRs for full-wave | Single device for full-wave |
| DC Switching | Yes (with commutation circuit) | No |
| Voltage Rating | Up to 1200V+ | Typically up to 800V |
| Best For | High-voltage, DC, half-wave control | AC load control, dimmers |
Why Choose TYN1225?
- 1200V Blocking Voltage — Safe margin for 230V/400V AC mains applications
- 25A Current Rating — Controls loads up to ~5.75kW @ 230V AC
- Low Gate Trigger (15mA) — Easily driven by optocoupler (MOC3021) or MCU via transistor
- STMicroelectronics Quality — Consistent parameters for reliable industrial designs
- TO-220 Package — Standard heatsink mounting for high-power operation
Typical Applications
- AC motor soft-start circuit (induction motor)
- Phase-angle power control (heater, lamp dimmer)
- Battery charger rectifier stage
- Crowbar overvoltage protection circuit
- AC power switch for industrial loads
- Welding machine power control
Typical Gate Drive Circuit
Use MOC3021 optocoupler for isolated gate drive from MCU. Gate resistor: 100–470Ω between optocoupler output and SCR gate. Add RC snubber (100Ω + 10nF) across anode-cathode for dV/dt protection.
FAQ
Q: How do I turn off a conducting SCR?
A: SCRs latch on once triggered. To turn off: reduce anode current below holding current (IH = 30mA) by removing load or using a commutation circuit. In AC circuits, the SCR turns off naturally at each zero-crossing.
Q: Can TYN1225 control a 3-phase motor?
A: Yes — use three pairs of back-to-back SCRs (one pair per phase) for 3-phase AC power control. Each pair replaces one TRIAC in a 3-phase controller.
Package Contents
- 5× TYN1225 TO-220 SCR Thyristor
