Diodes Incorporated SD1A240GW

Overview

SD1A240GW from Lite-On is a bidirectional silicon-controlled switch (SIDAC) designed for AC line-triggered switching in phase-control and relaxation oscillator circuits. It features ±180 V repetitive off-state voltage (VDRM/VRRM), 1 A RMS on-state current, 216–234 V typical breakover voltage (VBO), <65 mA dynamic holding current (IH), and DO-15 package. Used in solid-state relays and lamp dimmers requiring precise high-voltage turn-on.

For engineers reviewing the SD1A240GW datasheet, SD1A240GW pinout, SD1A240GW application, or SD1A240GW equivalent, key selection criteria include verified VBO tolerance (216–234 V), di/dt rating (80 A/μs), thermal resistance (18 °C/W), compact DO-15 footprint, and UL recognition (E219635).

Technical Context

The SD1A240GW operates as a two-terminal, bidirectional trigger device without gate control - conduction initiates when applied voltage exceeds its symmetric breakover threshold (VBO = 216–234 V). It sustains conduction until current falls below dynamic holding current (IH ≤ 65 mA) under 50–60 Hz sine wave conditions.

Its internal structure enables symmetrical forward/reverse blocking (±180 V), low leakage (<5 μA IDRM/IRRM), and robust surge capability (ITSM = ±20 A, 60 Hz one-cycle). Thermal performance is defined by RthJL = 18 °C/W with lead length 3/8″, supporting reliable operation from –40 to +125 °C junction temperature.

Key Specifications

Pinout & Package

SD1A240GW uses the axial-leaded DO-15 package (A = 25.4 mm, B = 3.60 mm, C = 2.60 mm, D = 0.71 mm, lead diameter = 0.86 mm). Two terminals only - no polarity or gate distinction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SIDAC applications.

Compared with NTE6408 and K2403S, SD1A240GW offers the narrowest VBO range (216–234 V), UL recognition, and optimal thermal resistance (18 °C/W) for compact DO-15 layouts - making it superior for precision timing and safety-compliant AC control.

Availability

SD1A240GW is available at Aetrix Electronics and suitable for lamp dimming, AC motor control, overvoltage protection, and relaxation oscillator timing requiring stable component supply and consistent VBO performance.

Supply support for SD1A240GW includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Lite-On Semiconductor (LSC) is a Taiwan-based semiconductor manufacturer specializing in optoelectronics, discrete power devices, and analog ICs, with global manufacturing and quality certifications.

The SD1A240GW belongs to Lite-On's SIDAC product line, engineered for high-reliability, zero-crossing–independent AC switching in cost-sensitive industrial and consumer controls.

FAQ

Is SD1A240GW a TRIAC or a SIDAC?

SD1A240GW is a SIDAC - a two-terminal, bidirectional trigger device without gate control. Unlike a TRIAC, it has no gate terminal and turns on solely when voltage across its terminals exceeds VBO (216–234 V). It conducts until current drops below IH (≤65 mA), then resets automatically.

Can SD1A240GW replace a DIAC in a light dimmer circuit?

Yes - SD1A240GW can directly replace standard DIACs (e.g., DB3) in TRIAC-based dimmers. Its higher VBO (216–234 V vs. ~32 V for DIACs) shifts firing angle later in the AC cycle, enabling deeper dimming range and reduced EMI due to slower dv/dt onset.

What is the maximum allowable lead temperature during soldering?

The maximum lead solder temperature is 260 °C for up to 10 seconds, measured at a point 1/16″ from the case body. Exceeding this risks internal bond wire damage or passivation layer degradation, compromising VBO stability and long-term reliability.

Does SD1A240GW require a heat sink in 1 A RMS operation?

No - at 1 A RMS with 3/8″ lead length and ambient ≤40 °C, junction temperature remains within –40 to +125 °C limits using RthJL = 18 °C/W. Heat sinking is unnecessary unless operating above 60 °C ambient or with >50% duty-cycle pulsed loads.