onsemi QVL21653

Overview

QVL21653 from Fairchild Semiconductor is a slotted optical switch integrating an infrared LED emitter and an NPN silicon phototransistor in a single injection-molded housing, designed for non-contact, wide-gap sensing. It features a 20 mm slot width, visible-light-filtering sensor, PC board mount, and operates across –40°C to +85°C.

For engineers reviewing the QVL21653 datasheet, pinout, applications, or equivalent options, key selection factors include its 20 mm gap geometry, coupled IC(ON) ≥100 µA at IF = 20 mA/VCE = 5 V, VCE(SAT) ≤0.5 V, and absolute max ratings including VR = 6 V (emitter), BVCEO = 30 V (sensor), and TSTG = –40°C to +85°C.

Technical Context

The QVL21653 implements a monolithic optocoupled architecture where infrared light from the emitter (Pins 1–2) crosses a fixed 20 mm air gap to trigger conduction in the NPN phototransistor (Pins 3–4). Its internal filter attenuates ambient visible light, enhancing noise immunity in industrial environments.

Electrical coupling is unidirectional and galvanically isolated; the output stage exhibits BVCEO ≥30 V and ICEO ≤100 nA at VCE = 10 V, supporting reliable switching in low-power digital detection circuits with minimal leakage and saturation voltage.

Key Specifications

Pinout & Package

QVL21653 uses a 4-pin DIP-style slotted package with 0.100" lead pitch and 0.138" ±0.02" slot depth. Housing includes .060" apertures and visible-light attenuation filter.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar slotted optical switch applications.

Compared with QVL21653, TTI-1000 offers higher output current but narrower gap and no optical filtering, while OPB920T51Z adds signal conditioning at the cost of added supply dependency and reduced gap - making QVL21653 optimal for wide-gap, ambient-resilient, supply-free detection.

Availability

QVL21653 is available at Aetrix Electronics and suitable for industrial automation, printer subsystems, and safety interlock systems requiring stable component supply and long-term manufacturability.

Supply support for QVL21653 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 IC manufacturer, acquired by ON Semiconductor in 2016; legacy products like QVL21653 remain widely supported in industrial designs.

The QVL21653 belongs to Fairchild's slotted optical switch family, engineered specifically for robust, maintenance-free position and presence sensing in harsh or space-constrained electromechanical systems.

FAQ

What is the maximum continuous forward current rating for the QVL21653 emitter?

The QVL21653 emitter has a maximum continuous forward current (IF) rating of 50 mA. This value is specified in the Absolute Maximum Ratings table and must not be exceeded to ensure long-term reliability. Derating applies above 25°C: power dissipation decreases by 1.67 mW/°C. Operating the QVL21653 at 20 mA, as used in typical coupled performance tests, provides ample margin while delivering ≥100 µA output current.

Does the QVL21653 require an external power supply for the phototransistor output stage?

No, the QVL21653 phototransistor output stage is passive and does not require a separate VCC supply. It functions as a current-sinking switch: when the IR emitter is forward-biased, incident light triggers collector current flow from an external pull-up network. The QVL21653 itself draws power only through the emitter pins (1 and 2); the output (pins 3 and 4) interfaces directly with logic inputs or microcontroller GPIOs using standard open-collector configuration.

What is the purpose of the visible-light filter in the QVL21653 housing?

The visible-light filter in the QVL21653 housing selectively attenuates wavelengths outside the near-infrared band emitted by the integrated LED (~850 nm). This minimizes false triggering caused by ambient fluorescent, LED, or incandescent lighting. In real-world deployments such as factory automation or office printers, this filter ensures stable switching behavior without requiring additional shielding or software debouncing - a key differentiator versus unfiltered optical switches like the QVL21653's predecessor QVL21652.

Can the QVL21653 be used in safety-critical door interlock applications?

The QVL21653 provides galvanic isolation and robust electrical specs (BVCEO ≥30 V, ICEO ≤100 nA), making it suitable for non-life-support safety interlocks - e.g., industrial cabinet door verification. However, it is not certified to IEC 61508 or ISO 13849, and Fairchild's life support policy explicitly excludes authorization for critical life-support systems. For QVL21653-based interlocks, system-level redundancy, validation, and compliance documentation remain the responsibility of the end-equipment designer.

What is the recommended soldering profile for the QVL21653?

The QVL21653 supports wave soldering at 260°C for 10 seconds and hand soldering at 240°C for 5 seconds. Lead-free processes are compatible if peak temperature remains within these limits. The datasheet specifies a minimum 1.6 mm distance between soldering iron tip and housing to prevent thermal damage to the plastic slot structure or internal optics. Methanol or isopropanol cleaning agents are recommended; RMA flux is preferred to avoid residue-induced optical scattering near the aperture.