Diodes Incorporated SD1A200E

Overview

SD1A200E from Littelfuse (formerly acquired from KEC/LSC) is a unidirectional silicon thyristor (SIDAC) designed for high-voltage, low-current switching in gas igniter circuits. It features a 170 V repetitive peak off-state voltage (V_DRM), 200 V nominal breakover voltage (V_BO), 1 A RMS on-state current rating at 80°C lead temperature, and a compact DO-41 plastic package.

For engineers reviewing the SD1A200E datasheet, SD1A200E pinout, SD1A200E application, or SD1A200E equivalent, key selection criteria include verified breakover voltage tolerance (190–210 V), holding current ≤60 mA, critical di/dt capability ≥80 A/μs, thermal resistance (R_thJC = 15 °C/W), and RoHS-compliant lead-free terminations.

Technical Context

The SD1A200E operates as a two-terminal, unidirectional trigger device that switches from blocking to conduction when forward voltage exceeds its temperature-dependent breakover threshold (V_BO). It latches on until current falls below the holding current (I_H ≤ 60 mA), with no gate control-unlike SCRs or TRIACs.

Its 80 A/μs minimum critical rate of rise of on-state current ensures reliable turn-on without false triggering under fast-rising transients. The 15 °C/W junction-to-case thermal resistance supports stable operation up to 125°C junction temperature in constrained PCB layouts.

Key Specifications

Pinout & Package

Package: JEDEC DO-41 molded plastic case with axial leads, RoHS-compliant lead-free plating, and 260°C max solder temperature (10 s, lead length ≥1/16″ from case).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar unidirectional thyristor trigger applications.

Compared with TN1215-600B and S6006L, the SD1A200E offers superior V_BO consistency (±5% vs. ±15–30%), DO-41 mechanical compatibility with legacy igniter PCBs, and optimal thermal resistance for sealed module integration-making it the preferred choice for UL/CSA-certified gas appliance ignition systems.

Availability

SD1A200E is available at Aetrix Electronics and suitable for gas igniters, furnace pilot light circuits, water heater ignition modules, and commercial oven safety interlocks requiring stable component supply and long-term manufacturability.

Supply support for SD1A200E 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

Littelfuse is a global manufacturer of circuit protection, power control, and sensing technologies, with expertise in discrete semiconductor switching devices for harsh-environment applications.

The SD1A200E belongs to Littelfuse's legacy SIDAC product line, originally developed for high-reliability, maintenance-free ignition in residential and commercial gas-fired equipment-emphasizing precision breakover voltage, thermal stability, and RoHS compliance.

FAQ

What is the maximum allowable junction temperature for continuous operation?

The SD1A200E has an operating junction temperature range of −40°C to +125°C. For continuous conduction at rated I_T(RMS) = 1 A, thermal design must ensure junction temperature remains ≤125°C, considering R_thJC = 15 °C/W and ambient conditions. Derating is required above 80°C lead temperature per datasheet curves.

Can SD1A200E be used in AC or DC circuits?

The SD1A200E is rated for AC line-frequency operation (50–60 Hz) and functions reliably in half-wave or full-wave configurations. It is not intended for pure DC blocking because its V_DRM rating applies only under repetitive sinusoidal conditions; sustained DC voltage may cause thermal runaway if current exceeds I_H.

Is SD1A200E pin-compatible with other DO-41 thyristors?

Yes-SD1A200E uses standard DO-41 axial package dimensions and lead spacing (0.300″ body length, 0.030″ lead diameter). However, electrical characteristics-including V_BO, I_H, and di/dt-are unique to this part; substitution requires validation of breakover timing and thermal performance in the target circuit.

Does SD1A200E require a snubber network?

A snubber is not mandatory for basic gas igniter use due to the device's 80 A/μs di/dt rating and low-energy discharge nature. However, in circuits with inductive loads or high dv/dt transients (e.g., near relay contacts), a 100 Ω + 100 pF RC snubber across A–K improves long-term reliability by limiting voltage overshoot during turn-off.