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Diodes Incorporated SD1A240E
- Part No.:
- SD1A240E
- Manufacturer:
- Diodes Incorporated
- Category:
- SCRs
- Package:
- -
- Datasheet:
-
SD1A240E.pdf
- Description:
- THYRISTOR DO-41 T&R 5K
- Quantity:
- Payment:
- Shipping:
Inventory:5,000
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Product details
Overview
SD1A240E from Littelfuse (formerly acquired from KEC/LSC) is a unidirectional SIDAC thyristor designed for high-voltage, low-current trigger applications in gas igniters. It features a 240 V nominal breakover voltage (VBO = 230–250 V), 210 V repetitive peak off-state voltage (VDRM), 1 A RMS on-state current rating, and ≤60 mA holding current (IH), operating across –40°C to +125°C junction temperature.
For engineers reviewing the SD1A240E datasheet, SD1A240E pinout, SD1A240E application, or SD1A240E equivalent, key selection criteria include verified breakover voltage tolerance, di/dt capability (≥220 A/μs), thermal resistance (RthJC = 15°C/W), RoHS-compliant DO-41 package, and suitability for capacitive discharge ignition circuits requiring precise voltage-triggered conduction.
Technical Context
The SD1A240E operates as a two-terminal, voltage-triggered negative-resistance device with no gate control - conduction initiates when applied voltage exceeds its temperature-dependent breakover threshold (VBO). Its intrinsic switching behavior eliminates need for external timing components in relaxation oscillator or pulse-generating circuits.
It exhibits a typical on-state voltage of 1.1–1.5 V at 1 A, critical rate of rise of on-state current (di/dt) ≥220 A/μs, and maintains stable VBO over –40°C to +125°C (±12% variation relative to 25°C baseline), enabling reliable operation in wide-temperature ignition environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBO Range | 230–250 Vdc: Defines precise voltage threshold for self-triggering conduction in capacitive discharge circuits |
| VDRM | 210 V: Maximum repetitive off-state blocking voltage - sets safe operating margin below VBO |
| IH Max | 60 mA: Minimum current required to sustain conduction after triggering - determines minimum load impedance |
| IT(RMS) | 1 A at TL = 80°C: Continuous RMS current handling capacity under defined heatsink condition |
| di/dt Min | 220 A/μs: Minimum rate of current rise tolerated during turn-on - prevents false triggering from transients |
| RthJC | 15°C/W: Thermal resistance from junction to case - enables thermal design with minimal heatsinking |
Pinout & Package
Package: JEDEC DO-41 molded plastic case with lead-free plating, RoHS 2011/65/EU compliant. Compact axial-leaded form factor optimized for PCB spacing efficiency in compact igniter modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | High-side terminal for voltage application and current entry during conduction | Connected to charged capacitor or HV supply rail; polarity-sensitive for unidirectional operation |
| Cathode (K) | Low-side terminal for current return path and reference | Typically grounded or tied to load return; defines directionality of breakover and conduction |
Key Features
| Feature | Design Value |
|---|---|
| Temperature-stable VBO | VBO varies only ±12% from –40°C to +125°C - ensures consistent ignition timing across environmental extremes |
| Low holding current | IH ≤ 60 mA - allows use with high-impedance loads (e.g., spark gap + series resistor) without latch-up risk |
| High di/dt immunity | ≥220 A/μs - suppresses spurious turn-on from EMI or fast-rising noise in ignition wiring harnesses |
| Compact DO-41 footprint | Standard axial package with 5.0 mm body diameter - fits legacy igniter PCB layouts without redesign |
Applications
| Gas Ignition Systems | Capacitive Discharge Igniters |
|---|---|
Use Scenario: Triggering spark generation in residential/commercial gas stoves and ovens using stored capacitor energy. IC Role / Device Role / Timing Role: Voltage-triggered switch that discharges HV capacitor across spark gap when line voltage crosses VBO threshold. Use Value: Eliminates need for separate timing IC or transformer-based ignition - reduces BOM count and system cost by 30% vs. coil-driven alternatives. | Use Scenario: High-reliability spark initiation in industrial gas burners where ambient temperature swings exceed 100°C. IC Role / Device Role / Timing Role: Unidirectional conduction switch activated solely by capacitor voltage - no external bias or control signal required. Use Value: Stable VBO drift (<±12%) ensures repeatable spark timing across –40°C to +125°C, meeting UL 350/UL 858 requirements. |
| Flame Detection Circuits | Appliance Safety Interlocks |
Use Scenario: Detecting presence of flame via ionization current path in gas-fired heating systems. IC Role / Device Role / Timing Role: Acts as latching element in flame-sensing feedback loop - conducts only when flame rectifies AC sensing voltage. Use Value: Low IH (≤60 mA) enables reliable detection with microamp-level ionization currents without false dropout. | Use Scenario: Enabling safety-critical power gating in gas valve control modules during fault conditions. IC Role / Device Role / Timing Role: Fail-safe switch that blocks valve power unless triggered by validated ignition sequence voltage profile. Use Value: VDRM = 210 V provides 30 V margin below 240 VAC mains - prevents unintended conduction during brownouts or surges. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar voltage-triggered thyristor applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SD1A240D | VBO range 220–240 V (lower center point); otherwise identical ratings and DO-41 package | Suitable for lower-voltage AC mains regions (e.g., 220 VAC systems); reduced margin against overvoltage stress | Select when tighter VBO tolerance at lower voltage is required; verify system surge immunity remains adequate |
| K240E | Same VBO (230–250 V), but VDRM = 200 V and RthJC = 20°C/W - higher thermal resistance and lower blocking margin | Acceptable in thermally relaxed designs with lower ambient or forced-air cooling; not recommended for sealed enclosures | Prefer SD1A240E where thermal headroom or 210 V VDRM margin is critical; K240E may reduce cost in non-constrained layouts |
Compared with SD1A240D and K240E, the SD1A240E offers the highest VDRM margin (210 V) and lowest thermal resistance (15°C/W), making it optimal for compact, high-ambient-temperature gas igniters requiring long-term reliability without derating.
Availability
SD1A240E is available at Aetrix Electronics and suitable for gas igniters, capacitive discharge circuits, flame detection systems, and appliance safety interlocks requiring stable component supply and RoHS-compliant discrete switching.
Supply support for SD1A240E 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 acquired the SIDAC product line from Korea Electronics Co. (KEC)/LSC and now manufactures and supports these devices under its circuit protection portfolio.
The SD1A240E belongs to Littelfuse's unidirectional SIDAC family, engineered specifically for robust, maintenance-free ignition and safety-critical switching in gas-fired appliances and industrial burners.
FAQ
What is the maximum allowable junction temperature for continuous operation?
The SD1A240E has an operating junction temperature range of –40°C to +125°C. Continuous operation must maintain TJ ≤ +125°C, achievable with proper PCB copper area or heatsinking given its RthJC of 15°C/W and 1 A IT(RMS) rating at TL = 80°C.
Can SD1A240E be used in AC line-switching applications?
No - the SD1A240E is a unidirectional device with cathode-anode polarity dependence and no reverse-blocking capability. It is intended for DC or half-wave AC trigger applications like capacitor discharge igniters, not full-wave AC switching.
How does the breakover voltage change with temperature?
VBO decreases linearly with rising junction temperature: Fig.3 shows VBO(TJ)/VBO(25°C) ratio drops to ~0.88 at +125°C, meaning VBO ≈ 211 V at max TJ. This is fully characterized and within specification - no external compensation is needed for ignition timing stability.
Is lead-free soldering compatible with SD1A240E's DO-41 package?
Yes - the SD1A240E uses lead-free terminal plating and is rated for maximum lead solder temperature of 260°C (10 s, lead length ≥1/16″ from case), fully compatible with standard lead-free reflow and hand-soldering processes per J-STD-020.
SD1A240E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Off State:
- -
- Voltage - Gate Trigger (Vgt) (Max):
- -
- Current - Gate Trigger (Igt) (Max):
- -
- Voltage - On State (Vtm) (Max):
- -
- Current - On State (It (AV)) (Max):
- -
- Current - On State (It (RMS)) (Max):
- -
- Current - Hold (Ih) (Max):
- -
- Current - Off State (Max):
- -
- Current - Non Rep. Surge 50, 60Hz (Itsm):
- -
- SCR Type:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SD1A240E FAQ
1.How can I place an order for SD1A240E through Aetrix?
Please submit a Request for Quotation (RFQ) for SD1A240E on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SD1A240E reliable?
The price and inventory of SD1A240E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SD1A240E is usually 5 days.
3.What payment methods are accepted for SD1A240E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SD1A240E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SD1A240E?
SD1A240E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SD1A240E order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SD1A240E?
For technical support, including SD1A240E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SD1A240E requirements.
6.How does Aetrix verify that SD1A240E is sourced from the original manufacturer or authorized distributors?
All SD1A240E products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SD1A240E meets industry standards.
7.What is the process for return or replacement of SD1A240E?
All SD1A240E units undergo pre-shipment inspection (PSI). If there is an issue with SD1A240E, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SD1A240E part is unused and in its original packaging.
Return procedure for SD1A240E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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