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Vishay Semiconductor Opto Division LH1540AT
- Part No.:
- LH1540AT
- Manufacturer:
- Vishay Semiconductor Opto Division
- Category:
- Solid State Relays (SSR)
- Package:
- 6-DIP (0.300", 7.62mm)
- Datasheet:
-
LH1540AT.pdf
- Description:
- SSR RELAY SPST-NO 120MA 0-350V
- Quantity:
- Payment:
- Shipping:
Inventory:252
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Product details
Overview
LH1540AT from Vishay Semiconductors is a 1-Form-A solid-state relay (SSR) with GaAlAs LED input and MOSFET output, providing normally open switching for AC/DC loads up to 350 V and 120 mA. It delivers 22 Ω typical on-resistance, 5300 VRMS isolation, and bounce-free operation - ideal for telecom line card protection and ground fault detection circuits.
For engineers reviewing the LH1540AT datasheet, LH1540AT pinout, LH1540AT application, or LH1540AT equivalent, this device is selected for high-isolation, low-power, electromechanical relay replacement in safety-critical industrial controls, security systems, and instrumentation where clean switching and long-term reliability are required.
Technical Context
The LH1540AT uses an optically isolated GaAlAs LED to drive complementary MOSFETs configured as a single-pole, single-throw (SPST) normally open switch. Its internal architecture enables bidirectional load handling in AC/DC configuration and unidirectional operation in DC-only mode.
It complies with DIN EN 60747-5-5 (VDE 0884), UL/cUL, and FIMKO safety standards, with 7 mm creepage/clearance and ≥0.4 mm insulation thickness. The device supports safe electrical insulation only within its rated isolation voltage (5300 VRMS) and transient voltage (8000 Vpeak) limits.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Isolation Voltage | 5300 VRMS - ensures reinforced insulation for mains-connected telecom and industrial equipment per UL1577 and VDE 0884. |
| Load Voltage Rating | 350 V - supports direct switching of 240 VAC RMS and 350 VDC lines without external snubbers. |
| Continuous Load Current | 120 mA (AC/DC) / 250 mA (DC only) - defines maximum steady-state current handling in respective configurations. |
| On-Resistance | 22 Ω typical (AC/DC), 5.2 Ω typical (DC only) - determines I²R power loss and voltage drop across the output switch. |
| Turn-On/Off Time | 0.13 ms / 0.05 ms typical - enables fast, bounce-free switching for pulse-width modulated control and digital logic interfacing. |
| Input Forward Current | 0.3–2 mA for turn-on - allows direct drive from low-power microcontrollers or logic gates without external current amplification. |
| Off-State Leakage | <1 nA at ±100 V, 6 nA at ±350 V - ensures minimal standby power draw and signal integrity in high-impedance sensing paths. |
Pinout & Package
DIP-6 package with 7.62 mm lead pitch, through-hole mounting, and UL/cUL/VDE safety-certified insulation structure.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Anode) | LED Anode Input | Positive terminal for GaAlAs LED; requires series resistor to limit IF to ≤50 mA. |
| 2 (Cathode) | LED Cathode Input | Ground return path for input LED; referenced to primary-side control circuitry. |
| 3 (Source) | MOSFET Source Terminal | Common source node for internal N-channel MOSFET; connected to load return in DC-only config. |
| 4 (Drain) | MOSFET Drain Terminal | Switched output node; connects to load high side in DC-only, or bidirectional load in AC/DC config. |
| 5 (NC) | No Connect | Internally unconnected; must remain floating - no routing or soldering allowed. |
| 6 (Source) | MOSFET Source Terminal | Second source terminal enabling symmetrical AC conduction path when used with pin 4. |
Key Features
| Feature | Design Value |
|---|---|
| 5300 VRMS Isolation | Enables safe separation between low-voltage control and hazardous AC mains or high-voltage DC bus. |
| Clean Bounce-Free Switching | Eliminates contact arcing and EMI associated with mechanical relays, critical for noise-sensitive telecom interfaces. |
| Low 0.3–2 mA Turn-On Threshold | Reduces driver circuit complexity and power consumption - compatible with 3.3 V and 5 V logic outputs. |
| 7 mm Creepage & Clearance | Meets reinforced insulation requirements for Pollution Degree 2 environments per IEC/EN 60664-1. |
| Material Compliance (Doc. 99912) | Confirms RoHS-compliant packaging and halogen-free construction for industrial and telecom compliance. |
Applications
| Telecom Line Card Protection | Security System Zone Monitoring |
|---|---|
|
Use Scenario: Isolating and switching subscriber line interface circuits (SLIC) during fault detection or loop-back testing. IC Role / Device Role / Timing Role: Solid-state relay providing galvanic isolation and SPST switching between controller and POTS line. Use Value: Prevents cross-talk and ground loops while enabling rapid, repeatable switching without mechanical wear. |
Use Scenario: Supervising door/window sensor inputs in access control panels with 24 VDC alarm loops. IC Role / Device Role / Timing Role: Isolated switch detecting open/closed states and isolating field wiring from panel logic. Use Value: Eliminates false alarms caused by induced transients and extends system lifetime beyond electromechanical relay limits. |
| Industrial PLC I/O Modules | Medical Equipment Safety Interlocks |
|
Use Scenario: Driving solenoid valves or indicator lamps in programmable logic controller output stages. IC Role / Device Role / Timing Role: Output-stage SSR replacing mechanical relays to improve cycle life and reduce maintenance. Use Value: Supports >10⁹ operations versus ~10⁵ for EM relays, reducing downtime in continuous process automation. |
Use Scenario: Enabling/disabling high-voltage subsystems (e.g., X-ray generator enable) based on door interlock status. IC Role / Device Role / Timing Role: Safety-rated isolation switch enforcing mandatory shutdown paths per IEC 62304. Use Value: Meets 5300 VRMS withstand and 8000 Vpeak transient ratings required for Class II medical device isolation barriers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar solid-state relay applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Vishay LH1540AAB | SMD-6 package; same electrical specs but surface-mount footprint and 0.79 mm lead height. | Preferred for automated PCB assembly and space-constrained telecom modules. | Select LH1540AAB when board real estate or reflow compatibility is prioritized over through-hole serviceability. |
| IXYS CPC1976Y | Higher 400 V load rating, 350 mA DC current, but 3750 VRMS isolation and no VDE certification. | Suitable for higher-power industrial controls but not drop-in for safety-certified telecom designs. | Choose CPC1976Y only after verifying revised creepage, clearance, and agency approval alignment with end-equipment requirements. |
Compared with LH1540AAB and CPC1976Y, the LH1540AT offers DIP-6 through-hole mounting for prototyping and repair-friendly layouts, full VDE/UL/cUL/FIMKO certification for global telecom deployment, and optimized 120 mA AC/DC switching performance at 350 V - making it the preferred choice where safety compliance and serviceability are non-negotiable.
Availability
LH1540AT is available at Aetrix Electronics and suitable for telecom infrastructure, security system manufacturing, and industrial PLC development requiring stable component supply and long-lifecycle support.
Supply support for LH1540AT 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
Vishay Intertechnology is a global semiconductor manufacturer specializing in discrete components, sensors, and optoelectronics with emphasis on reliability, precision, and safety certification.
The LH1540AT belongs to Vishay's LH-series solid-state relay family, engineered specifically for high-isolation, low-power, electromechanical relay replacement in telecom, industrial, and medical safety-critical systems.
FAQ
What is the maximum ambient temperature rating for continuous operation of the LH1540AT?
The LH1540AT is rated for continuous operation from −40 °C to +85 °C ambient temperature. At 85 °C, its maximum continuous load current drops to 100 mA in AC/DC configuration per Fig. 5 in the datasheet. Derating curves for output safety power (PSO) and input safety current (ISI) are provided on pages 4–5 to ensure thermal compliance under worst-case conditions.
Does the LH1540AT support AC load switching, and what is its configuration?
Yes, the LH1540AT supports bidirectional AC load switching in its AC/DC configuration using pins 4 (Drain) and 6 (Source) as complementary output terminals. This configuration enables zero-crossing–free switching up to 350 V peak, with 22 Ω typical on-resistance and <1 nA off-state leakage at ±100 V - verified in the Electrical Characteristics table on page 2.
What safety certifications does the LH1540AT hold, and which standards do they cover?
The LH1540AT holds UL, cUL, FIMKO, and DIN EN 60747-5-5 (VDE 0884) certifications. These validate its 5300 VRMS isolation voltage, 8000 Vpeak transient withstand, 7 mm creepage/clearance, and reinforced insulation structure - meeting requirements for safety-critical telecom and industrial equipment per IEC 61000-4 and IEC 62368-1.
Can the LH1540AT be driven directly from a 3.3 V microcontroller GPIO?
Yes, the LH1540AT can be driven directly from a 3.3 V microcontroller GPIO. Its turn-on forward current requirement is only 0.3–2 mA (IFon), and forward voltage is 1.4–1.6 V at 10 mA. A 1 kΩ series resistor limits current to ~1.7 mA at 3.3 V, satisfying the minimum turn-on threshold without additional buffering.
What is the purpose of Pin 5 on the LH1540AT, and how should it be handled in layout?
Pin 5 on the LH1540AT is a no-connect (NC) terminal - internally unconnected and electrically isolated. It must remain floating in PCB layout: no trace routing, no soldering, and no connection to ground or any other net. This is explicitly stated in the Pin Configuration diagram (Fig. 1) and confirmed in the Package Marking section on page 7.
LH1540AT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Vishay Semiconductor Opto Division
- Series:
- LH1540
- Packaging:
- Tube
- Product Status:
- Active
- Mounting Type:
- Through Hole
- Circuit:
- SPST-NO (1 Form A)
- Output Type:
- AC, DC
- Voltage - Input:
- 1.26VDC
- Voltage - Load:
- 0 V ~ 350 V
- Load Current:
- 120 mA
- On-State Resistance (Max):
- 20 Ohms
- Termination Style:
- PC Pin
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 6-DIP
- Approval Agency:
- cUL, DIN, FIMKO, UL
- Grade:
- -
- Qualification:
- -
LH1540AT FAQ
1.How can I place an order for LH1540AT through Aetrix?
Please submit a Request for Quotation (RFQ) for LH1540AT 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 LH1540AT reliable?
The price and inventory of LH1540AT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LH1540AT is usually 5 days.
3.What payment methods are accepted for LH1540AT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LH1540AT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LH1540AT?
LH1540AT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LH1540AT 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 LH1540AT?
For technical support, including LH1540AT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LH1540AT requirements.
6.How does Aetrix verify that LH1540AT is sourced from the original manufacturer or authorized distributors?
All LH1540AT 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 LH1540AT meets industry standards.
7.What is the process for return or replacement of LH1540AT?
All LH1540AT units undergo pre-shipment inspection (PSI). If there is an issue with LH1540AT, 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 LH1540AT part is unused and in its original packaging.
Return procedure for LH1540AT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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