NXP BT136S-600D,118 Triac: Datasheet, Pinout, and Application Circuit Guide
The BT136S-600D,118 from NXP Semiconductors is a standard four-quadrant Triac, a pivotal component for AC power control in a vast array of electronic applications. This guide provides a detailed overview of its datasheet specifications, pinout configuration, and a fundamental application circuit to get your design started.
Datasheet Overview and Key Specifications
The BT136S-600D,118 is designed for medium-power AC switching. Its robust construction and reliable performance make it a popular choice for industrial and consumer goods. Key parameters from its datasheet include:
Repetitive Peak Off-State Voltage (Vdrm): 600 V. This high voltage rating ensures reliable operation in standard 110V and 230V AC mains applications, providing a good safety margin against voltage spikes.
On-State RMS Current (It(rms)): 4 A. This makes it suitable for controlling a wide range of loads up to this current level, such as motors, heaters, and incandescent lamps.
Gate Trigger Current (Igt): 5 mA to 35 mA. This relatively low trigger current allows it to be driven directly from microcontrollers (like Arduino or ESP32) using an optocoupler, simplifying the control circuitry.
Package:SOT54 (TO-252AA, DPAK). This surface-mount package offers a good balance between power handling capability and board space efficiency, suitable for automated assembly processes.
Pinout Configuration
Correctly identifying the pins is crucial for circuit functionality and safety. The BT136S-600D,118 comes in a three-pin SOT54 package:
1. MT1 (Main Terminal 1): This is the reference terminal for the gate trigger pulse. It is often connected to the neutral or live line, depending on the circuit design, and is typically the pin with the largest tab for heat dissipation.
2. MT2 (Main Terminal 2): The main power terminal. This is connected in series with the load to the AC supply.
3. G (Gate): The control terminal. A brief positive or negative current pulse applied between the Gate and MT1 will trigger the Triac into conduction.
Warning: Always consult the latest manufacturer datasheet for the definitive pinout diagram before PCB layout, as it can vary between packages.
Standard Application Circuit: AC Dimmer
A classic application for the BT136S-600D,118 is a phase-angle control dimmer for an AC lamp or a motor speed controller. The basic circuit consists of a few key components:
Triac (BT136S-600D,118): The main switching element.
Diac (e.g., DB3): A bidirectional trigger device that provides the sharp voltage pulse needed to reliably trigger the Triac's gate. It breaks over at a typical voltage of 30V.
Potentiometer (Rpot): A variable resistor used to adjust the RC time constant, thereby controlling the phase angle at which the Triac is triggered each half-cycle.
Resistor (R): A fixed resistor to limit the current through the Diac and the Triac's gate.
Capacitor (C): Forms an RC timing circuit with the potentiometer.
How it Works: The RC network (Rpot, R, and C) causes a phase shift in the AC waveform. The capacitor voltage charges until it reaches the breakover voltage of the Diac. The Diac then fires, discharging the capacitor into the gate of the Triac and turning it on. The Triac will remain on for the remainder of that half-cycle of AC power. By adjusting the potentiometer, you change the timing of the trigger pulse, which in turn varies the average power delivered to the load.
For microcontroller-based control, the Diac and RC network are replaced by an optoisolator Triac driver (e.g., MOC3021). This provides crucial galvanic isolation, protecting the low-voltage microcontroller from the high-voltage AC mains. The MCU sends a pulse to the LED inside the optocoupler, which internally triggers a phototriac that provides the gate current to the main BT136S Triac.
ICGOODFIND Summary
The NXP BT136S-600D,118 is a highly versatile and robust 4A Triac, perfectly suited for a multitude of AC switching and phase-control tasks. Its 600V voltage rating and SOT54 package offer a great blend of resilience and modern manufacturing compatibility. Its ability to be triggered by a low gate current makes it an ideal choice for designs ranging from simple DIY dimmers to sophisticated microcontroller-managed systems, especially when paired with an isolating optocoupler for safety.
Keywords: Triac, AC Power Control, Phase-Angle Control, Solid-State Relay, BT136S.
