The AQY214EHAZ is a PhotoMOS solid-state relay (SSR) manufactured by Panasonic, designed for high-voltage, high-isolation switching applications. It integrates an infrared LED input with a MOSFET output, offering 5,000 Vrms reinforced insulation and fast switching in a compact DIP-4 surface-mount package. 

1. Core Functionality and Architecture

Opto-isolated Design: Combines an AlGaAs infrared LED (input) and a high-voltage MOSFET (output) with 5,000 Vrms isolation (加强绝缘), ensuring safety in high-voltage environments.

Single-Throw Configuration: Features a 1 Form A (SPST-NO) contact arrangement, where the MOSFET switches the load circuit when the LED is energized.

Bidirectional Load Support: Handles both AC and DC loads up to 400 V and 120 mA continuous current, with a peak load capability of 0.3 A (100 ms pulse).

2. Key Technical Parameters

Input Requirements:

LED Forward Current: 5–10 mA (recommended) for reliable switching; minimum turn-on current is 0.4 mA.

LED Forward Voltage: 1.25–1.5 V (typ. 1.25 V at 5 mA).

Reverse Voltage: 5 V (max) to prevent LED damage.

Output Performance:

On-Resistance: 26–35 Ω (typ. 26 Ω), increasing with temperature (e.g., up to 40 Ω at 85°C).

Off-State Leakage Current: ≤1 μA, ensuring minimal standby power consumption.

Switching Speed:

Turn-On Time: 0.5 ms (typ.), 2.0 ms (max).

Turn-Off Time: 0.08 ms (typ.), 1.0 ms (max).

Electrical Ratings:

Isolation Voltage: 5,000 Vrms (1 minute), compliant with safety standards like EN 60950.

Output Capacitance: 0.8–1.5 pF (typ. 1.5 pF), affecting high-frequency signal integrity.

Environmental Limits:

Operating Temperature: -40°C to +85°C (industrial grade).

Storage Temperature: -40°C to +100°C.

3. Pin Configuration and Functionality

Pins 1–2: Infrared LED input (anode/cathode). Apply ≥5 mA to activate the MOSFET.

Pins 3–4: MOSFET output (drain/source). Conducts when the LED is energized; high-impedance when off.

Package: DIP-4 (6.4 × 4.78 × 2.9 mm), with gull-wing terminals for surface-mount soldering.

4. Operation Principle

Input Activation:

Applying ≥5 mA to the LED (Vf = 1.25–1.5 V) generates infrared light, triggering the MOSFET to conduct between pins 3 and 4.

The MOSFET fully turns on within 0.5 ms and off within 0.08 ms when the LED current drops below 0.4 mA.

Isolation and Safety:

The 5,000 Vrms barrier between input and output ensures protection against electrical surges and ground loops.

Reinforced insulation meets strict safety requirements for industrial and telecom systems.

Load Handling:

Supports bidirectional AC/DC loads up to 400 V and 120 mA. Derate to 60 mA at 85°C due to thermal constraints.

Low on-resistance (26–35 Ω) minimizes power dissipation (e.g., 0.12 A × 35 Ω = 0.5 W).

5. Typical Applications

Automated Test Equipment (ATE): Switches high-voltage signals in semiconductor testing with minimal signal distortion.

Telecom and Security Systems: Controls low-level analog signals (e.g., telephone lines) with high isolation.

Industrial Control: Manages relays, solenoids, or sensors in PLCs and robotics.

Medical Devices: Ensures safety in equipment requiring galvanic isolation (e.g., patient monitoring systems).

High-Frequency Switching: Fast switching speed (0.08 ms off-time) makes it suitable for PWM applications.