Diodes Incorporated SD1A220E

Overview

SD1A220E from LSC is a unidirectional silicon thyristor (SIDAC) designed for high-voltage AC switching in gas igniter circuits, with a 220 V breakover voltage (V_BO = 210–230 V), 190 V peak repetitive off-state voltage (V_DRM), and 1 A RMS on-state current rating at 80°C lead temperature.

For engineers reviewing the SD1A220E datasheet, SD1A220E pinout, SD1A220E application, or SD1A220E equivalent, key selection criteria include breakover voltage tolerance, holding current (<60 mA), di/dt capability (220 A/μs), thermal resistance (15 °C/W), and DO-41 package compatibility with high-temperature ignition environments.

Technical Context

The SD1A220E operates as a voltage-triggered bidirectional switch without gate control - it conducts when applied voltage exceeds its temperature-dependent breakover threshold (V_BO = 220 V nominal at 25°C, varying ±10 V across -40 to +125°C junction range). It latches on until current falls below 60 mA holding current (I_H).

Its 220 A/μs critical rate of rise of on-state current (di/dt) ensures reliable turn-on under fast-rising AC transients, while its 15 °C/W junction-to-case thermal resistance supports sustained 1 A RMS conduction in compact DO-41 packages with adequate heatsinking.

Key Specifications

Pinout & Package

Package: JEDEC DO-41 molded plastic case with lead-free plating, RoHS-compliant (2011/65/EU), rated for 260°C soldering (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 switching applications.

Compared with ST1A220 and Vishay S1A220E, SD1A220E offers the lowest holding current (≤60 mA) and best thermal resistance (15 °C/W), making it optimal for fast-turn-off, thermally constrained gas igniter designs requiring minimal standby leakage and efficient board-level heat transfer.

Availability

SD1A220E is available at Aetrix Electronics and suitable for gas igniters, appliance safety interlocks, industrial burner controls, and commercial oven igniters requiring stable component supply with tight V_BO tolerance and high di/dt immunity.

Supply support for SD1A220E 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

LSC (Littelfuse Semiconductor Corporation) is a global supplier of discrete power semiconductors specializing in protection, switching, and control devices for industrial and consumer applications.

The SD1A220E belongs to LSC's SIDAC family engineered specifically for contactless, self-triggered AC ignition in gas-fired appliances - prioritizing voltage accuracy, thermal stability, and long-term reliability under cyclic thermal stress.

FAQ

What is the maximum junction temperature for continuous operation?

The SD1A220E has an operating junction temperature range of -40°C to +125°C. Continuous conduction at full 1 A RMS requires maintaining lead temperature at ≤80°C per the datasheet derating curve; exceeding this reduces safe operating area and accelerates parameter drift, especially in V_BO and I_H.

Can SD1A220E be used in DC circuits?

No - SD1A220E is a unidirectional thyristor optimized for AC line-synchronized triggering. In DC, once triggered, it remains latched until current drops below 60 mA holding current, which cannot occur without external commutation. It lacks gate control and is not rated for DC blocking or forced turn-off.

How does junction temperature affect breakover voltage?

V_BO decreases by approximately 0.1% per °C rise above 25°C, as shown in Figure 3 of the datasheet. At +125°C junction, V_BO is ~90% of its 25°C value (i.e., ~198 V), requiring system-level design margin to ensure reliable triggering across the full operating range.

Is SD1A220E RoHS-compliant and halogen-free?

Yes - the device meets RoHS Directive 2011/65/EU, uses lead-free terminal plating, and is manufactured in a halogen-free molding compound. Compliance documentation is available upon request and verified through LSC's material declarations and third-party test reports.