onsemi H22A5

Overview

H22A5 from Fairchild Semiconductor is a slotted optical switch (photointerrupter) with an integrated phototransistor output, 0.185" (4.7 mm) slot width, 70 V collector-emitter breakdown voltage, and 50 mA continuous collector current, used for position sensing and object detection in industrial encoders and printer paper-path monitoring.

For engineers reviewing the H22A5 datasheet, pinout, applications, or equivalent options, key selection criteria include slot geometry compatibility, phototransistor saturation behavior under varying ambient light, dark current stability over temperature, and mounting orientation constraints in space-constrained mechanical assemblies.

Technical Context

The H22A5 employs an infrared LED emitter paired with a silicon NPN phototransistor in a single molded package, operating in digital on/off mode without internal amplification or hysteresis. Its optical path is defined by a rigid 4.7 mm wide, 1.0 mm deep slot that mechanically isolates emitter and detector while enabling reliable interruption detection.

Electrical operation requires external biasing of the phototransistor collector via a pull-up resistor; output logic state transitions between saturated low (≤0.4 V at I_C = 10 mA) and open-collector high-impedance when unilluminated. Device response time is specified as 15 µs turn-on and 20 µs turn-off at 10 mA LED drive current.

Key Specifications

Pinout & Package

Package: 4-pin DIP (dual in-line package) with through-hole mounting, 0.300" row spacing, and integral slot cavity formed between pins 1–2 (emitter) and pins 3–4 (detector).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar photointerrupter applications.

Compared with the Everlight ITL2000 and Vishay TCST2103, the H22A5 offers superior voltage handling and isolation for 24 V industrial control, while trading off some speed and optical sensitivity-making it optimal for robust, safety-conscious motion feedback where mechanical clearance and electrical safety dominate design priorities.

Availability

H22A5 is available at Aetrix Electronics and suitable for industrial encoder feedback, printer paper jam detection, automated door safety edges, and conveyor belt object counting requiring stable component supply and long-term manufacturability.

Supply support for H22A5 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

Fairchild Semiconductor was a U.S.-based analog and power semiconductor manufacturer, acquired by ON Semiconductor in 2016; known for high-reliability optoelectronic and power devices.

The H22A5 belongs to Fairchild's legacy slotted optoswitch product line, designed specifically for ruggedized position and presence sensing in factory automation, office equipment, and safety-critical electromechanical systems.

FAQ

What is the maximum recommended LED forward current for continuous operation of the H22A5?

The H22A5 datasheet specifies 60 mA as the absolute maximum DC forward current for the infrared LED, but Fairchild recommends 50 mA as the maximum continuous operating current to ensure long-term reliability and stable optical output over temperature. Derating to 40 mA is advised for designs operating above 65°C ambient. The H22A5 must always be used with a series current-limiting resistor calculated for the applied supply voltage and desired LED current.

Does the H22A5 require external pull-up resistors on its output, and what value is typical?

Yes, the H22A5 phototransistor output is open-collector and requires an external pull-up resistor. A 4.7 kΩ resistor to 5 V is typical for logic-level interfacing, yielding ~1 mA collector current and fast rise time. For 24 V systems, a 10 kΩ resistor limits collector dissipation while maintaining TTL compatibility. The H22A5 output saturates below 0.4 V at 10 mA load, ensuring clean low-state definition.

Can the H22A5 be used in environments with high ambient light exposure, such as near windows or fluorescent lighting?

The H22A5 incorporates an infrared LED and matched phototransistor with spectral filtering to reject visible light, making it resistant to typical indoor ambient sources. However, direct sunlight or intense IR-rich sources (e.g., halogen lamps) may cause false triggering. For such cases, mechanical shielding or pulsed LED drive synchronized with phototransistor sampling-as implemented in some H22A5-based designs-improves noise immunity. The H22A5 itself does not include built-in modulation.

What is the minimum detectable object thickness for reliable interruption of the H22A5 optical path?

The H22A5 has a nominal slot width of 4.7 mm and depth of 1.0 mm; objects ≥0.5 mm thick reliably block the infrared beam across the full slot aperture. Thinner objects (e.g., 0.2 mm wires or film) may partially transmit light depending on material opacity and alignment. Mechanical registration features on the H22A5 package aid consistent positioning. For precision thin-object detection, the H22A5 should be evaluated with actual target materials under end-use conditions.

Is the H22A5 RoHS compliant and lead-free?

Yes, the H22A5 was manufactured in RoHS-compliant, lead-free versions prior to Fairchild's acquisition by ON Semiconductor. Units supplied by Aetrix Electronics meet EU RoHS Directive 2011/65/EU requirements, with lead content <1000 ppm and no restricted substances above threshold limits. The H22A5 packaging carries the "Pb-Free" marking, and full compliance documentation is available upon request for the H22A5.