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STMicroelectronics MSS40-1200
- Part No.:
- MSS40-1200
- Manufacturer:
- STMicroelectronics
- Category:
- SCRs - Modules
- Package:
- ISOTOP
- Datasheet:
-
MSS40-1200.pdf
- Description:
- MODULE SCR BACK TO BACK ISOTOP
- Quantity:
- Payment:
- Shipping:
Inventory:9,194
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Product details
Overview
MSS40-1200 from STMicroelectronics is a back-to-back SCR module in ISOTOP package, configured as two anti-parallel thyristors for AC phase control. It delivers 55 A RMS on-state current at 80°C case temperature, 1200 V repetitive peak off-state voltage (VDRM/VRRM), and 50 A/µs critical dI/dt rating. It is used in solid-state relays and industrial heating control systems requiring high noise immunity and galvanic isolation.
For engineers reviewing the MSS40-1200 datasheet, MSS40-1200 pinout, MSS40-1200 application, or MSS40-1200 equivalent, key selection criteria include RMS current derating vs. case temperature, gate trigger current (IGT ≤ 50 mA), thermal resistance (Rth(j-c) = 0.6 °C/W), and UL-certified 2500 VRMS insulation.
Technical Context
The MSS40-1200 integrates two monolithic SCRs in inverse parallel within a single ISOTOP housing, enabling bidirectional AC conduction without external wiring. Its internal ceramic pad ensures 2500 VRMS isolation, meeting UL E81734. The device operates with gate-triggered turn-on and natural commutation at current zero-crossing.
It supports phase-angle control in resistive and inductive loads, with validated holding current (IH ≤ 80 mA) and latching current (IL ≤ 120 mA) across –40°C to +125°C junction range. Surge capability is rated at 420 A (tp = 16.7 ms) and I²t = 800 A²s (tp = 10 ms).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IT(RMS) | 55 A at Tc = 80°C - defines maximum continuous AC load current before thermal shutdown |
| VDRM / VRRM | 1200 V - peak repetitive blocking voltage per thyristor, enabling use in 690 VAC three-phase systems |
| IGT | ≤ 50 mA - maximum gate trigger current required, compatible with standard microcontroller GPIO or optocoupler drivers |
| Rth(j-c) | 0.6 °C/W - junction-to-case thermal resistance, determines heatsink sizing for 55 A operation |
| dI/dt | 50 A/µs - minimum rate of rise of on-state current before false triggering, critical for inductive load snubbing |
| Isolation Voltage | 2500 VRMS - reinforced insulation barrier between power terminals and mounting base, UL-certified |
| VTM | ≤ 1.7 V at 80–100 A - on-state voltage drop, directly impacts conduction loss and thermal design |
Pinout & Package
Package: ISOTOP - insulated, screw-mount power module with integrated ceramic insulator, 6×M4 mounting screws, 27 g mass (without screws), UL94 V0 epoxy body.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1 | Thyristor 1 Anode | Main terminal for first SCR; connects to line/load side in AC switching path |
| A2 | Thyristor 2 Anode | Main terminal for second SCR; oriented opposite to A1 to enable back-to-back conduction |
| G1 | Thyristor 2 Gate | Control input for second SCR; requires ≥5 mA trigger pulse with <100 ns rise time |
| G2 | Thyristor 1 Gate | Control input for first SCR; electrically isolated from G1 to support independent or complementary gating |
Key Features
| Feature | Design Value |
|---|---|
| Back-to-back SCR configuration | Enables full-wave AC switching in a single package, eliminating discrete anti-parallel assembly and layout complexity |
| UL-certified 2500 VRMS isolation | Meets safety requirements for industrial mains-connected equipment without additional isolation barriers |
| 0.6 °C/W thermal resistance | Supports compact heatsink designs for 55 A RMS operation at ≤80°C case temperature |
| 50 A/µs dI/dt rating | Ensures reliable turn-on under fast-rising inductive currents, reducing need for aggressive snubbers |
| ECOPACK® lead-free construction | Complies with RoHS and JEDEC JESD97 marking standards for second-level interconnect |
Applications
| Solid-State Relay (SSR) | Industrial Heating Control |
|---|---|
Use Scenario: Replacement for electromechanical relays in PLC output modules driving resistive heaters up to 15 kW. IC Role / Device Role / Timing Role: Bidirectional AC power switch controlled by low-voltage logic signal; conducts during both half-cycles when triggered. Use Value: Eliminates contact wear and bounce, enables silent operation and >10⁹ cycle lifetime at rated current. | Use Scenario: Phase-angle control in temperature-regulated furnace systems using PID feedback. IC Role / Device Role / Timing Role: Thyristor-based AC power modulator; gate timing adjusted per control loop to regulate average power. Use Value: Precise thermal management with 1200 V blocking margin for 400–690 VAC supply variations. |
| Welding Equipment | Motor Speed Controller |
Use Scenario: Primary AC switching in resistance spot welders requiring high surge current handling. IC Role / Device Role / Timing Role: High-current AC switch triggered synchronously with line zero-crossing to minimize EMI. Use Value: Withstands 420 A non-repetitive surge (16.7 ms) and delivers I²t = 800 A²s for weld energy consistency. | Use Scenario: Single-phase AC induction motor speed control in HVAC blowers and pumps. IC Role / Device Role / Timing Role: Back-to-back SCR providing variable RMS voltage to motor windings via phase-cutting. Use Value: Maintains torque at reduced speed with 55 A RMS rating and 80°C thermal limit for continuous duty. |
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 MDA55-1200 | Higher IT(RMS) = 55 A at Tc = 95°C; Rth(j-c) = 0.55 °C/W; no UL certification | Preferred where higher ambient temperature operation is needed but safety agency approval is not mandated | Select when thermal margin is critical and UL isolation is handled externally |
| Powerex CM100DY-12H | Dual IGBT module (not SCR); 100 A rating; requires active gate drive and desaturation protection | Suitable for PWM-based motor drives, not phase-control heating or SSRs | Choose only for switched-mode topologies requiring zero-crossing independence and faster switching |
Compared with MDA55-1200 and CM100DY-12H, MSS40-1200 offers certified isolation and simpler gate drive for phase-control applications, while trading off thermal headroom and switching flexibility.
Availability
MSS40-1200 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 MSS40-1200 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, Switzerland, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.
The MSS series was developed specifically for high-reliability AC power control in industrial automation, emphasizing robustness, isolation integrity, and thermal efficiency in compact power modules.
FAQ
What is the maximum case temperature for continuous 55 A RMS operation?
The MSS40-1200 is rated for 55 A RMS at Tc = 80°C. Exceeding this temperature requires linear derating per Figure 3 in the datasheet: at 90°C case, max RMS current drops to ~45 A. Heatsink design must maintain baseplate temperature ≤80°C under worst-case ambient and airflow conditions.
Can MSS40-1200 be used with zero-crossing trigger circuits?
No - MSS40-1200 is designed for phase-angle control, not zero-crossing switching. Its gate trigger characteristics (IGT ≤ 50 mA, IH ≤ 80 mA) require precise timing relative to the AC waveform. Zero-crossing operation would cause unreliable turn-on due to insufficient gate current near voltage zero.
Is the ISOTOP package compatible with standard heatsink mounting hardware?
Yes - the ISOTOP package uses six M4 mounting screws (two for heatsink attachment, four provided for board or terminal mounting). Recommended torque is 0.9 Nm (max 1.2 Nm). Mounting surface flatness must be ≤0.05 mm over 30 mm to ensure uniform thermal contact and dielectric integrity.
Does MSS40-1200 require a snubber circuit in inductive load applications?
Yes - due to its 50 A/µs dI/dt rating, a properly sized RC snubber is required for inductive loads (e.g., motors, solenoids) to suppress voltage transients during turn-off. Failure to do so risks false triggering or dv/dt-induced failure, especially at high junction temperatures.
MSS40-1200 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):
- 55 A
- Voltage - Gate Trigger (Vgt) (Max):
- 1.3 V
- Current - Gate Trigger (Igt) (Max):
- 50 mA
- Current - Non Rep. Surge 50, 60Hz (Itsm):
- 400A, 420A
- Current - Hold (Ih) (Max):
- 80 mA
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Chassis Mount
MSS40-1200 FAQ
1.How can I place an order for MSS40-1200 through Aetrix?
Please submit a Request for Quotation (RFQ) for MSS40-1200 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 MSS40-1200 reliable?
The price and inventory of MSS40-1200 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MSS40-1200 is usually 5 days.
3.What payment methods are accepted for MSS40-1200?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MSS40-1200 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MSS40-1200?
MSS40-1200 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MSS40-1200 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 MSS40-1200?
For technical support, including MSS40-1200 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MSS40-1200 requirements.
6.How does Aetrix verify that MSS40-1200 is sourced from the original manufacturer or authorized distributors?
All MSS40-1200 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 MSS40-1200 meets industry standards.
7.What is the process for return or replacement of MSS40-1200?
All MSS40-1200 units undergo pre-shipment inspection (PSI). If there is an issue with MSS40-1200, 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 MSS40-1200 part is unused and in its original packaging.
Return procedure for MSS40-1200:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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