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STMicroelectronics ACS108-8SA-TR
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- Part No.:
- ACS108-8SA-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TRIACs
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
ACS108-8SA-TR.pdf
- Description:
- TRIAC SENS GATE 800V 0.45A TO92
- Quantity:
- Payment:
- Shipping:
Inventory:437
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Product details
Overview
ACS108-8SA-TR from STMicroelectronics is a single-pole, 0.8 A RMS, 800 V blocking voltage AC switch with integrated overvoltage crowbar protection (VCL ≥ 850 V), negative-gate-triggered operation (IGT ≤ 10 mA), and TO-92 package. It replaces discrete triac + snubber designs in low-power AC load switching for appliances and industrial controls.
For engineers reviewing the ACS108-8SA-TR datasheet, ACS108-8SA-TR pinout, ACS108-8SA-TR application, or ACS108-8SA-TR equivalent, this device offers verified IEC 61000-4-5 surge immunity (2 kV), dV/dt immunity ≥ 2000 V/μs at 125 °C, direct microcontroller interface via gate resistor, and no external varistor or snubber requirement.
Technical Context
The ACS108-8SA-TR integrates an A.S.D.® (Advanced Static Discharge) structure enabling self-protecting turn-off of highly inductive loads (up to 15 H) without external clamping components. Its gate-level shifter isolates digital controllers from mains-referenced switching paths while accepting negative gate current (IGT ≤ 10 mA) for triggering.
It operates in Quadrants II and III only, with clamping action initiated when VOUT exceeds VCL (≥ 850 V), followed by controlled crowbar conduction to dissipate stored inductive energy. Thermal design is constrained by Rth(j-l) = 60 °C/W and Tj(max) = 125 °C under natural convection on FR4 PCB.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IT(RMS) | 0.8 A - Maximum continuous AC load current at Ttab = 76 °C, suitable for solenoids, valves, and small motors. |
| VDRM / VRRM | 800 V - Blocking voltage rating ensures safe operation on 230 VAC mains with margin for transients. |
| IGT | ≤ 10 mA - Gate trigger current threshold enables direct drive from MCU GPIO with 220 Ω series resistor. |
| VCL | ≥ 850 V - Clamping voltage headroom before crowbar activation protects against inductive turn-off spikes. |
| dV/dt immunity | ≥ 2000 V/μs at 125 °C - Prevents false triggering from EMI or fast line transients without snubber. |
| Rd | ≤ 300 mΩ - Low dynamic on-state resistance minimizes power loss and thermal rise at full load. |
| ITSM (tp = 20 ms) | 13 A - Non-repetitive surge current rating supports motor startup and relay coil energization peaks. |
Pinout & Package
Package: TO-92 with common tab connection (COM pin electrically tied to metal tab), lead-free plating, halogen-free epoxy (UL94 V0).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COM | Common reference terminal | Connected to AC mains neutral or ground; tab-mounted for shared heatsinking with other AC switches. |
| OUT | Load output terminal | Switched AC output connected to lamp, solenoid, or fan; referenced to COM for bidirectional conduction. |
| G | Negative gate input | Receives sinking current (≤10 mA) from MCU GPIO; triggers conduction only in Quadrants II/III. |
Key Features
| Feature | Design Value |
|---|---|
| Overvoltage crowbar protection | VCL ≥ 850 V enables safe turn-off of 15 H inductive loads without external snubber or varistor. |
| IEC 61000-4-5 surge ruggedness | Withstands ±2 kV line-to-line surges per IEC 61000-4-5 test circuit, eliminating need for external TVS. |
| Direct microcontroller interface | Gate accepts 10 mA sinking current; compatible with 3.3 V/5 V GPIO using 220 Ω series resistor. |
| Shared thermal pad capability | TO-92 metal tab (COM) allows mounting multiple ACS devices on one heatsink for multi-channel AC control. |
| High noise immunity | 2000 V/μs dV/dt immunity at 125 °C prevents false triggering in noisy industrial environments. |
Applications
| Appliance Solenoid Control | Industrial Valve Actuation |
|---|---|
|
Use Scenario: Controlling water/gas solenoid valves in washing machines, dishwashers, and HVAC systems. IC Role / Device Role / Timing Role: AC mains switch replacing mechanical relays; triggered once per cycle during zero-crossing window. Use Value: Eliminates relay contact wear, reduces acoustic noise, and cuts BOM count by removing snubber components. |
Use Scenario: Driving pneumatic or hydraulic control valves in PLC-based factory automation panels. IC Role / Device Role / Timing Role: Solid-state AC switch interfacing directly with isolated digital outputs of industrial controllers. Use Value: Enables compact DIN-rail mounted modules with shared heatsinking across multiple channels. |
| Low-Power Fan Regulation | Lamp Dimming Interface |
|
Use Scenario: On/off control of AC-powered cooling fans in medical equipment and embedded enclosures. IC Role / Device Role / Timing Role: Mains-referenced switching element handling resistive-inductive fan loads up to 0.8 A RMS. Use Value: Provides silent, spark-free switching with built-in surge protection for long-term reliability. |
Use Scenario: Replacing electromechanical switches in decorative or task lighting circuits (incandescent/halogen). IC Role / Device Role / Timing Role: Zero-voltage turn-on capable AC switch supporting phase-cut dimming compatibility. Use Value: Delivers flicker-free lamp control with no audible buzz and no external protection components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar AC switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ACS108-6SA-TR | 600 V VDRM instead of 800 V; identical IT(RMS), IGT, and package. | Suitable only for 120 VAC systems or low-surge environments; not rated for 230 VAC + IEC 61000-4-5 compliance. | Select when operating on North American 120 VAC mains and cost optimization is prioritized over surge margin. |
| BT134-800E | Standard triac without crowbar protection; requires external RC snubber and MOV for surge immunity. | Higher BOM count and board area; lacks VCL clamping and fails IEC 61000-4-5 without added components. | Choose only if legacy triac footprint reuse is mandatory and system-level protection is already implemented externally. |
Compared with ACS108-6SA-TR, the ACS108-8SA-TR provides essential 800 V blocking margin for 230 VAC global deployments and certified surge resilience; versus BT134-800E, it eliminates snubber design effort and improves long-term reliability in inductive load cycling.
Availability
ACS108-8SA-TR is available at Aetrix Electronics and suitable for appliance solenoid control, industrial valve actuation, low-power fan regulation, and lamp dimming interfaces requiring stable component supply and long lifecycle support.
Supply support for ACS108-8SA-TR 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.
The ACS™ AC switch product line targets solid-state replacement of electromechanical relays in low-power AC load control, emphasizing integrated surge protection, simplified drive, and thermal efficiency in compact packages.
FAQ
What is the correct gate driving method for ACS108-8SA-TR?
The ACS108-8SA-TR requires a negative gate current-i.e., current must flow *out* of the G pin into the controller's sinking output. A 220 Ω resistor between a 3.3 V or 5 V MCU GPIO and G ensures IGT ≤ 10 mA. Do not apply positive voltage or source current to G, as it will not trigger conduction.
Can ACS108-8SA-TR replace a standard triac in existing designs?
Yes, but only if the existing layout accommodates TO-92 pinout (COM–OUT–G) and the application does not rely on Quadrant I or IV triggering. Unlike standard triacs, ACS108-8SA-TR operates only in Quadrants II and III and provides built-in overvoltage clamping-eliminating snubber components but requiring gate current direction verification.
What is the maximum inductance this device can safely switch off?
Per ST application note AN4715, the ACS108-8SA-TR has been validated for safe turn-off of inductive loads up to 15 H at 0.8 A RMS, provided VCL ≥ 850 V clamps the resulting overvoltage and the energy (½ × L × I²) falls within the device's I²t rating (1.1 A²s for tp = 10 ms).
Does ACS108-8SA-TR require heatsinking in typical applications?
At 0.8 A RMS with natural convection on FR4 PCB, junction temperature remains below 125 °C when ambient stays ≤ 64 °C (per Figure 2). For continuous operation above 64 °C ambient or in enclosed spaces, a small copper pour connected to the COM tab (Rth(j-l) = 60 °C/W) is sufficient-no external heatsink needed.
ACS108-8SA-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- ACS™/A.S.D®
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Packaging:
- Cut Tape (CT)
- Product Status:
- Active
- Triac Type:
- Logic - Sensitive Gate
- Voltage - Off State:
- 800 V
- Current - On State (It (RMS)) (Max):
- 450 mA
- Voltage - Gate Trigger (Vgt) (Max):
- 1 V
- Current - Non Rep. Surge 50, 60Hz (Itsm):
- 13A, 13.7A
- Current - Gate Trigger (Igt) (Max):
- 10 mA
- Current - Hold (Ih) (Max):
- 10 mA
- Configuration:
- Single
- Operating Temperature:
- -30°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92
ACS108-8SA-TR FAQ
1.How can I place an order for ACS108-8SA-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for ACS108-8SA-TR 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 ACS108-8SA-TR reliable?
The price and inventory of ACS108-8SA-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ACS108-8SA-TR is usually 5 days.
3.What payment methods are accepted for ACS108-8SA-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ACS108-8SA-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ACS108-8SA-TR?
ACS108-8SA-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ACS108-8SA-TR 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 ACS108-8SA-TR?
For technical support, including ACS108-8SA-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ACS108-8SA-TR requirements.
6.How does Aetrix verify that ACS108-8SA-TR is sourced from the original manufacturer or authorized distributors?
All ACS108-8SA-TR 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 ACS108-8SA-TR meets industry standards.
7.What is the process for return or replacement of ACS108-8SA-TR?
All ACS108-8SA-TR units undergo pre-shipment inspection (PSI). If there is an issue with ACS108-8SA-TR, 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 ACS108-8SA-TR part is unused and in its original packaging.
Return procedure for ACS108-8SA-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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