Both NO and NC contacts incorporated in a compact DIP8-pin Reinforced insulation# Technical Documentation: AQW614EHAX Solid State Relay (SSR)
Manufacturer : Panasonic
Component Type : Photovoltaic MOSFET Output Solid State Relay (SSR)
---
## 1. Application Scenarios
### 1.1 Typical Use Cases
The AQW614EHAX is a photovoltaic-isolated, single-pole, normally open (1-Form-A) solid-state relay designed for low-power AC/DC switching applications. Its core function is to provide electrical isolation and silent, bounce-free switching between a low-voltage control circuit and a load circuit.
* Low-Power Signal Switching: Ideal for switching analog or digital signals in test equipment, data acquisition systems, and communication interfaces where mechanical relay contact bounce and wear are unacceptable.
* Battery-Powered Systems: Its extremely low input current requirement (typically 0.5 mA) makes it suitable for microcontroller GPIO pin driving in portable, battery-sensitive devices.
* Ground Loop Elimination: The high isolation voltage (5000 Vrms) allows it to break ground loops when connecting sensors or signals between different system grounds, preventing noise and interference.
* Replacement for Reed Relays: A direct upgrade path for reed relays in applications requiring higher reliability, faster switching, and longer life, such as in medical instrumentation and automated test equipment (ATE).
### 1.2 Industry Applications
* Industrial Automation: Used in PLC output modules, I/O interfaces, and for switching sensors and low-current actuators. Its robust construction resists vibration and contamination.
* Telecommunications: Employed in line card circuits, subscriber line interfaces (SLICs), and test access points for routing low-level audio and control signals.
* Medical Electronics: Critical in patient monitoring equipment, diagnostic devices, and laboratory analyzers where silent, reliable, and isolated switching of bio-signals or sensor inputs is required.
* Test & Measurement: Found in multiplexers, scanner cards, and instrument switching matrices where signal integrity and long-term calibration stability are paramount.
* Energy Management: Used in smart meters and power monitoring systems for isolated sampling and switching of voltage/current signals.
### 1.3 Practical Advantages and Limitations
Advantages:
* Long Life & High Reliability: No moving parts, eliminating contact arcing, wear, and bounce. Operational life is typically in the billions of cycles.
* Low Input Power Consumption: The integrated photovoltaic generator allows direct drive from CMOS logic or microcontroller pins without needing a pre-driver circuit.
* Excellent Isolation: 5000 Vrms input-to-output isolation provides safety and noise immunity.
* Fast Switching: Turn-on/off times in the millisecond range, significantly faster than most electromechanical relays (EMRs).
* Silent Operation: No audible click during switching.
* Compact & Sealed: The SOP4 surface-mount package is small and suitable for wave soldering.
Limitations:
* Limited Current Capacity: Maximum continuous output current is 170 mA. It is not suitable for switching mains-powered loads like motors or lamps directly.
* On-Resistance: The MOSFET output has a finite on-resistance (typically 10 Ω), which causes a voltage drop and power dissipation (I²R loss) across the relay when conducting.
* Leakage Current: A small off-state leakage current (typically 0.01 µA) flows through the output, which can be critical in very high-impedance signal paths.
* Thermal Considerations: Power dissipation in the on-state must be calculated (P = I_load² * R_on) to ensure the junction temperature remains within limits, especially in high ambient temperatures or without adequate PCB copper for heat sinking.
---
## 2. Design Considerations
### 2.1 Common Design Pit
