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STMicroelectronics MSS50-1200
- Part No.:
- MSS50-1200
- Manufacturer:
- STMicroelectronics
- Category:
- SCRs - Modules
- Package:
- ISOTOP
- Datasheet:
-
MSS50-1200.pdf
- Description:
- MODULE SCR BACK TO BACK ISOTOP
- Quantity:
- Payment:
- Shipping:
Inventory:7,749
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Product details
Overview
MSS50-1200 from STMicroelectronics is a dual back-to-back SCR module in ISOTOP package, rated for 70 A RMS on-state current and 1200 V repetitive peak off-state voltage, with 50 A/µs critical dI/dt rating and 2500 VRMS isolation. It serves as a high-noise-immunity AC power switching device in solid-state relays and industrial heating control systems.
For engineers reviewing the MSS50-1200 datasheet, MSS50-1200 pinout, MSS50-1200 application, or MSS50-1200 equivalent, key selection factors include verified RMS current derating at Tc = 85 °C, gate trigger current (IGT ≤ 50 mA), thermal resistance (Rth(j-c) = 0.45 °C/W), and UL-certified insulation performance.
Technical Context
The MSS50-1200 integrates two anti-parallel SCRs in a single ISOTOP module, enabling bidirectional AC conduction without external reverse-blocking components. Its internal ceramic pad ensures 2500 VRMS isolation, meeting UL E81734 requirements.
It operates with gate-triggered turn-on only; no self-commutation capability. Electrical behavior is defined by threshold voltage (Vt0 ≤ 0.85 V) and dynamic resistance (Rd ≤ 7 mΩ) at Tj = 125 °C, supporting stable conduction under high-current transient loads up to ITSM = 630 A (tp = 16.7 ms).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IT(RMS) | 70 A at Tc = 85 °C - defines maximum continuous AC load current with heatsink cooling |
| VDRM / VRRM | 1200 V - peak off-state voltage rating for reliable blocking in 600–800 VAC line applications |
| IGT | ≤ 50 mA - maximum gate trigger current required for reliable turn-on under worst-case conditions |
| Rth(j-c) | 0.45 °C/W - junction-to-case thermal resistance enabling precise heatsink sizing for 70 A operation |
| dI/dt | 50 A/µs - minimum critical rate of rise of on-state current before false triggering occurs |
| Vt0 / Rd | 0.85 V / 7 mΩ - conduction threshold and dynamic resistance determining on-state power loss at high current |
| I²t (tp=10 ms) | 1800 A²s - fusing energy rating used to coordinate upstream fuse protection |
Pinout & Package
Package: ISOTOP - 4-terminal, epoxy-encapsulated, UL94 V0 compliant module with integrated ceramic insulation and M4 screw mounting (0.9 Nm recommended torque). Dimensions: 38.0 × 25.3 × 8.0 mm (L × W × H).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1 | Thyristor 1 Anode | Main terminal for AC phase leg 1; connects to load or line side in SSR configuration |
| A2 | Thyristor 2 Anode | Main terminal for AC phase leg 2; enables full-wave AC switching when paired with A1 |
| G1 | Thyristor 2 Gate | Control input for thyristor conducting during negative half-cycle of AC waveform |
| G2 | Thyristor 1 Gate | Control input for thyristor conducting during positive half-cycle of AC waveform |
Key Features
| Feature | Design Value |
|---|---|
| Back-to-back SCR topology | Enables bidirectional AC switching in single package-eliminates need for discrete anti-parallel SCR pairing |
| 2500 VRMS isolation | UL-certified creepage/clearance via internal ceramic pad-meets safety requirements for industrial mains interfaces |
| 0.45 °C/W thermal resistance | Supports 70 A RMS operation with moderate heatsink size-reduces thermal design overhead vs. discrete alternatives |
| 50 A/µs dI/dt immunity | Prevents false triggering under fast-rising load currents typical in motor and transformer inrush scenarios |
| ECOPACK® lead-free construction | Complies with JEDEC JESD97 marking and RoHS; second-level interconnect fully Pb-free |
Applications
| Solid-State Relay (SSR) | Industrial Heating Control |
|---|---|
Use Scenario: Replacing electromechanical relays in PLC output modules for AC load switching up to 25 kW. IC Role / Device Role / Timing Role: Bidirectional AC power switch controlled by low-voltage logic-level gate signals. Use Value: Eliminates contact wear and bounce; supports >10⁷ switching cycles with zero arc generation. | Use Scenario: Phase-angle or zero-crossing control of resistive heating elements in furnace temperature regulation. IC Role / Device Role / Timing Role: High-current AC power valve synchronized to mains zero-crossing or phase-shifted firing angle. Use Value: Delivers precise thermal power delivery with <±0.5% RMS current stability over 0–100% duty range. |
| Welding Equipment Power Stage | Motor Speed Controller |
Use Scenario: Primary AC power switching in resistance spot welders requiring high surge current handling. IC Role / Device Role / Timing Role: Main current path switch triggered synchronously with welding cycle timing controller. Use Value: Withstands 630 A non-repetitive surge (tp = 16.7 ms) and delivers I²t = 1800 A²s for robust short-circuit coordination. | Use Scenario: Single-phase AC induction motor soft-start and speed regulation in HVAC blowers and pumps. IC Role / Device Role / Timing Role: Bidirectional AC power modulator driven by microcontroller-based phase-control algorithm. Use Value: Enables smooth torque ramp-up and 10:1 speed range with <3% speed regulation error across load variations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar back-to-back SCR module applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IXYS LCA120-12IO1 | 120 A RMS rating, Rth(j-c) = 0.35 °C/W, higher cost, TO-247-4L package | Supports higher continuous current but requires larger heatsink footprint and different mounting | Select when >70 A RMS or lower thermal resistance is required; not drop-in compatible due to pinout and footprint mismatch |
| Powerex CM100DY-24NF | Dual IGBT + diode module, 100 A/1200 V, gate drive required, no inherent AC commutation | Requires active gate control and external freewheeling paths; unsuitable for simple phase-control without added circuitry | Choose only for PWM-based variable-frequency drive designs-not a functional substitute for SCR-based phase-angle control |
Compared with LCA120-12IO1 and CM100DY-24NF, the MSS50-1200 offers optimized simplicity for fixed-frequency AC phase control: it needs no gate driver IC, supports direct logic-level triggering, and provides intrinsic bidirectional conduction-reducing BOM count and layout complexity in SSR and heater control designs.
Availability
MSS50-1200 is available at Aetrix Electronics and suitable for solid-state relays, industrial heating control systems, and welding equipment requiring stable component supply and long-term industrial lifecycle support.
Supply support for MSS50-1200 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.
The MSS series targets high-reliability AC power control applications, emphasizing noise immunity, UL-certified isolation, and compact high-power density packaging for industrial automation and energy systems.
FAQ
What is the maximum case temperature for continuous 70 A RMS operation?
The MSS50-1200 is rated for 70 A RMS at Tc = 85 °C, as specified in Table 3. Operation above this temperature requires derating per Figure 3. Sustained case temperatures beyond 85 °C risk exceeding the 125 °C maximum junction temperature, leading to premature failure or loss of latching behavior.
Can MSS50-1200 be used in zero-crossing switching mode?
Yes - its gate trigger sensitivity (IGT ≤ 50 mA) and fast turn-on time allow synchronization with zero-crossing detection circuits. However, zero-crossing operation must ensure gate pulse timing aligns within ±100 µs of actual zero crossing to avoid misfiring or asymmetrical conduction.
Is heatsink mounting torque specified, and what happens if exceeded?
The recommended torque is 0.9 Nm (max 1.2 Nm) for the six M4 screws. Exceeding 1.2 Nm risks cracking the ISOTOP epoxy body or deforming the internal ceramic pad, compromising 2500 VRMS isolation and thermal performance. Mounting flatness and surface finish (Ra ≤ 1.6 µm) are also critical for Rth(j-c) compliance.
Does MSS50-1200 require snubber circuits in inductive load applications?
Yes - for inductive loads (e.g., motors, solenoids), a parallel RC snubber (e.g., 100 Ω + 0.1 µF) across A1–A2 is required to suppress dv/dt-induced false triggering. The device's dV/dt rating is 1000 V/µs (min) at Tj = 125 °C, but real-world transients often exceed this without suppression.
MSS50-1200 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- ISOTOP
- Packaging:
- Tube
- Product Status:
- Obsolete
- Structure:
- 1-Phase Controller - All SCRs
- Number of SCRs, Diodes:
- 2 SCRs
- Voltage - Off State:
- 1.2 kV
- Current - On State (It (AV)) (Max):
- -
- Current - On State (It (RMS)) (Max):
- 70 A
- Voltage - Gate Trigger (Vgt) (Max):
- 1.3 V
- Current - Gate Trigger (Igt) (Max):
- 50 mA
- Current - Non Rep. Surge 50, 60Hz (Itsm):
- 600A, 630A
- Current - Hold (Ih) (Max):
- 80 mA
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Chassis Mount
MSS50-1200 FAQ
1.How can I place an order for MSS50-1200 through Aetrix?
Please submit a Request for Quotation (RFQ) for MSS50-1200 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 MSS50-1200 reliable?
The price and inventory of MSS50-1200 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MSS50-1200 is usually 5 days.
3.What payment methods are accepted for MSS50-1200?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MSS50-1200 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MSS50-1200?
MSS50-1200 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MSS50-1200 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 MSS50-1200?
For technical support, including MSS50-1200 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MSS50-1200 requirements.
6.How does Aetrix verify that MSS50-1200 is sourced from the original manufacturer or authorized distributors?
All MSS50-1200 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 MSS50-1200 meets industry standards.
7.What is the process for return or replacement of MSS50-1200?
All MSS50-1200 units undergo pre-shipment inspection (PSI). If there is an issue with MSS50-1200, 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 MSS50-1200 part is unused and in its original packaging.
Return procedure for MSS50-1200:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MSS50-1200 Tags
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TT190N16SOFHPSA2
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CLA60PD1200NA
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MCC56-16IO1B
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TD120N16SOFHPSA1
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MCC95-12IO1B
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MCMA140P1600TA
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B512F-2
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