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The BT151-650R SCR (Silicon Controlled Rectifier) is a widely used power semiconductor designed for controlling and switching medium- to high-power AC and DC loads. This article will discuss the BT151-650R SCR’s basics, pinout, working principles, applications, specifications, features, and more.
The NXP Semiconductors BT151-650R is a silicon controlled rectifier (SCR) designed for reliable switching and control of high-power AC and DC loads. As a thyristor, it remains off until a small gate current is applied, after which it latches on and conducts current between the anode and cathode until the current falls below its holding level.
This device supports up to 650 V blocking voltage and around 12 A RMS on-state current, making it suitable for demanding power applications. Housed in a TO-220 package, it allows easy through-hole mounting and effective heat dissipation when used with a heatsink. Its sensitive gate characteristics enable simple triggering from low-power control circuits.
If you are interested in purchasing the BT151-650R, feel free to contact us for pricing and availability.
| Pin No. | Pin Name | Description |
| 1 | Anode (A) | Main current-carrying terminal. Current flows from anode to cathode when the SCR is triggered. |
| 2 | Cathode (K) | Main return terminal. The SCR turns off when current through this pin falls below the holding current. |
| 3 | Gate (G) | Control terminal. A small gate current triggers the SCR into conduction. |
• BT152-600
• BT152-650
• TYN208
• TYN612
• 2N6508
• S6010
• C106M
• BT169
| Parameter | Specification |
| Product Type | Silicon Controlled Rectifier (SCR) |
| Manufacturer | NXP Semiconductors (original design) |
| Repetitive Peak Off-State Voltage (VDRM) | 650 V |
| Repetitive Peak Reverse Voltage (VRRM) | 650 V |
| RMS On-State Current (IT(RMS)) | 12 A |
| Average On-State Current (IT(AV)) | 7.5 A |
| Surge On-State Current (ITSM) | 95 A (non-repetitive) |
| Gate Trigger Current (IGT) | ≤ 15 mA |
| Gate Trigger Voltage (VGT) | ≤ 1.5 V |
| Holding Current (IH) | ≤ 15 mA |
| Latching Current (IL) | ≤ 25 mA |
| On-State Voltage (VT) | ~1.6 V |
| Operating Junction Temperature | −40 °C to +125 °C |
| Package Type | TO-220 (SOT78) |
| Mounting Type | Through-hole |
| Tab Connection | Anode (A) |
The BT151-650R can withstand repetitive peak voltages up to 650 V in both forward and reverse directions when it is in the off state. This high blocking capability makes it suitable for mains-powered and industrial circuits where voltage transients and high line voltages are common.
This SCR is designed to handle up to 12 A RMS of continuous on-state current, with the ability to tolerate much higher surge currents for short durations. This allows it to reliably control motors, heaters, and other power-hungry loads without performance degradation.
The device requires only a small gate current to turn on, enabling easy triggering from low-power control circuits such as microcontrollers, optocouplers, or simple transistor drivers. This feature simplifies circuit design and reduces control-side power consumption.
The BT151-650R operates reliably across a wide temperature range, making it suitable for both consumer and industrial environments where thermal conditions may vary significantly.
Once triggered, the BT151-650R remains in the conducting state until the load current drops below the holding current. This latching behavior is ideal for AC power control and protection circuits where stable on-state conduction is required.
Housed in a TO-220 package, the SCR offers good mechanical strength and efficient heat dissipation. The package allows direct mounting to a heatsink, helping maintain safe operating temperatures under high current conditions.
In the provided circuit, the BT151-650R SCR is used as a latching electronic switch to control a 12 V DC motor. When the SCR is off, no current flows through the motor, so it remains stopped. The SCR is placed in series with the motor, allowing it to control the motor’s power directly.
When the START push button is pressed, a small gate current flows through resistor R1 to the gate of the BT151-650R. This gate current triggers the SCR into conduction, allowing current to flow from the supply through the SCR and the motor. Resistor R2 helps stabilize the gate reference and limits current, ensuring reliable triggering.
After the START button is released, the motor continues to run because the SCR remains latched on. The motor current stays above the SCR’s holding current, keeping it conducting. Pressing the STOP button interrupts the current path, reducing the SCR current below its holding level and turning it off, which stops the motor.
• DC motor start–stop control circuits
• AC motor control systems
• Heater and temperature control circuits
• Lamp dimmers and lighting control
• Power supply switching stages
• Battery-powered load switching
• Overvoltage and crowbar protection circuits
• Industrial power control equipment
• Relay and solenoid driving circuits
• General-purpose AC/DC power switching
Operate the BT151-650R within its rated voltage and current limits to avoid damage. Use proper gate resistors to limit gate current and prevent gate overstress. Provide adequate heatsinking to control temperature during high-current operation. When driving inductive loads, add protection such as snubber circuits to suppress voltage spikes. Always ensure correct wiring and polarity before powering the circuit.
NXP Semiconductors has long-standing manufacturing expertise in power semiconductor devices, including SCRs such as the BT151-650R, originating from its history as Philips Semiconductors. Leveraging mature silicon processing, high-voltage device fabrication, and robust assembly and testing technologies, NXP was able to produce reliable, high-current thyristors for industrial and consumer power control applications.
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