Vishay Semiconductor Opto Division LH1501BT

Overview

LH1501BT from Vishay Semiconductors is a 1-Form-B solid-state relay (SSR) with DIP-6 package, designed as a bounce-free, optically isolated SPST normally closed switch. It features 3750 VRMS input-output isolation, 350 V load voltage rating, ≤25 Ω on-resistance (AC/DC), and operates across –40 °C to +85 °C ambient for industrial control and telecom switching applications.

For engineers reviewing the LH1501BT datasheet, LH1501BT pinout, LH1501BT application, or LH1501BT equivalent, this page delivers verified electrical specs, terminal roles, agency-approved use cases, and real-world selection guidance for replacing electromechanical relays in AC/DC load switching circuits.

Technical Context

The LH1501BT integrates an infrared LED input stage coupled to a photodiode array driving dual MOSFET output switches with internal control circuitry - enabling bidirectional AC/DC conduction in a normally closed configuration. Its hybrid multi-chip construction ensures galvanic isolation without mechanical contacts.

It supports both unidirectional (200 mA DC max) and bidirectional (150 mA DC max) load current operation, with turn-on/turn-off times of 2–3 ms and 1–3 ms respectively at 5 mA LED drive. Output capacitance is 35 pF, and input-to-output capacitance is only 3 pF, minimizing signal coupling.

Key Specifications

Pinout & Package

DIP-6 through-hole package with 2.54 mm pin pitch, 7.62 mm body width, and 9.144 mm length per Vishay Doc. 83805. RoHS-compliant, lead-free finish, rated for wave soldering (260 °C, 10 s max).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar solid-state relay applications.

Compared with LH1501BABTR and CPC1976Y, the LH1501BT provides through-hole mounting convenience and NC default state critical for fail-safe industrial controls, while maintaining identical isolation and timing performance - making it optimal for legacy designs and manual assembly workflows.

Availability

LH1501BT is available at Aetrix Electronics and suitable for industrial controls, telecom switching, and security equipment requiring stable component supply with long-term lifecycle support and full traceability.

Supply support for LH1501BT 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 over 50 years of reliability engineering heritage.

The LH1501BT belongs to Vishay's LH1501 family of optically coupled solid-state relays, engineered specifically to replace electromechanical relays in high-reliability, low-maintenance industrial and telecom infrastructure.

FAQ

What is the default state of the LH1501BT output?

The LH1501BT is a normally closed (Form B) solid-state relay: its output terminals (pins 4/6 to 5) conduct when the input LED is unpowered. Applying ≥0.9 mA forward current to pins 1–2 opens the output path. This fail-safe behavior ensures continuity in case of controller failure or power loss - a key requirement in security and safety-critical LH1501BT deployments.

Can the LH1501BT switch AC loads?

Yes, the LH1501BT supports bidirectional AC/DC operation up to 350 V peak. Its internal dual-MOSFET output structure allows conduction in both directions, enabling direct replacement of EM relays in 120/240 VAC circuits such as lighting control or HVAC actuation - provided load current remains within the 150 mA DC (or equivalent RMS) limit specified in the LH1501BT datasheet.

What is the maximum continuous load current rating for the LH1501BT?

The LH1501BT supports 150 mA continuous DC load current in bidirectional (AC/DC) mode and 200 mA in unidirectional DC mode. Derating applies above 50 °C ambient: Fig. 1 in Vishay Doc. 83805 shows linear reduction to ~90 mA at +85 °C. Exceeding these limits risks thermal shutdown or accelerated parametric drift in the LH1501BT's hybrid output stage.

Does the LH1501BT require external snubber circuitry?

No snubber is required for resistive or lightly inductive loads within its 350 V / 150 mA ratings. The LH1501BT's integrated MOSFETs and control circuitry provide inherent voltage clamping and zero-crossing–free switching robustness. However, highly inductive loads (e.g., solenoids >100 mH) may benefit from an RC snubber across pins 4/6–5 to suppress L·di/dt transients - consult Vishay Application Note AN-301 for LH1501BT-specific guidance.

How does the LH1501BT achieve 3750 VRMS isolation?

The LH1501BT achieves 3750 VRMS input-output isolation via physical separation of LED and photodiode/MOSFET die within a ceramic-filled epoxy DIP-6 package, validated per UL 1577 and VDE EN 60747-5-5. Creepage and clearance distances exceed 7.6 mm, and the internal insulation barrier withstands 1-second AC test at 3750 VRMS with leakage <10 μA - a specification rigorously confirmed during LH1501BT production lot testing.