QSD733 Equivalent & Substitute Parts

Part Overview

The QSD733 is a phototransistor optical sensor manufactured by onsemi, designed for 880nm wavelength detection in a top-view TO-18-2 package configuration. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement continuity. The QSD733 operates through-hole mounted applications requiring photoelectric sensing in the near-infrared spectrum.

Substiute Parts

QSD733

onsemiIn Stock: 1020QSD733 Datasheet

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OP598A

TT Electronics/Optek TechnologyIn Stock: 1656OP598A Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the QSD733 is determined by the following critical parameters:

• Package Compatibility: TO-18-2 through-hole configuration required for mechanical and electrical interface compatibility
• Wavelength Sensitivity: 880nm nominal detection wavelength; substitutes within 10nm variance (880-890nm) maintain functional equivalence
• Orientation: Top-view configuration mandatory for optical path alignment
• Electrical Ratings: Collector-emitter breakdown voltage minimum 30V; dark current maximum 100nA; power dissipation capability minimum 100mW
• Operating Temperature Range: -40°C to 100°C minimum required
• Mounting Type: Through-hole only; surface-mount alternatives are not compatible

The OP598A meets all substitution criteria within these parameters.

Parameter Comparison

Engineering Selection Recommendations

The OP598A is a direct substitute for the QSD733 based on the following factors:

• Mechanical Compatibility: Identical TO-18-2 package and through-hole mounting configuration ensure PCB-level compatibility without redesign
• Electrical Equivalence: Matching collector-emitter breakdown voltage (30V) and dark current specifications (100nA max) maintain circuit performance parameters
• Wavelength Alignment: 890nm detection wavelength represents a 10nm shift from the 880nm specification, acceptable for near-infrared photoelectric applications
• Power Capability: OP598A 250mW maximum power rating exceeds the QSD733 100mW requirement, providing operational margin
• Product Status: OP598A is actively manufactured by TT Electronics/Optek Technology, ensuring long-term availability and supply chain continuity
• Compliance: OP598A holds ROHS3 compliance certification, meeting modern regulatory requirements

Frequently Asked Questions (FAQ)

Q: Can the OP598A be used as a direct pin-for-pin replacement for the QSD733?

A: Yes. Both components use the TO-18-2 package with identical pinout configuration. No circuit modifications are required for mechanical or electrical interface compatibility.

Q: What is the significance of the 10nm wavelength difference between 880nm and 890nm?

A: The 10nm variance falls within the typical spectral response curve tolerance for phototransistor applications. Both wavelengths operate in the near-infrared spectrum with overlapping sensitivity ranges. Application-specific testing may be required if the original design depends on precise 880nm wavelength selectivity.

Q: Why is the OP598A rated for 250mW maximum power while the QSD733 is rated for 100mW?

A: The OP598A has a higher power dissipation capability, which provides additional thermal margin during operation. This does not affect substitution compatibility; the circuit design should continue to operate within the original 100mW power budget.

Q: Is the OP598A available in the same packaging options as the QSD733?

A: The OP598A is supplied in bulk packaging, whereas the QSD733 was available in standard packaging. Both use the TO-18-2 case format. Verify packaging and tape-reel availability with your supplier for production requirements.

Q: What compliance certifications apply to the OP598A?

A: The OP598A is ROHS3 compliant and REACH unaffected. Both components carry EAR99 ECCN classification and share the same HTSUS code (8541.49.7080).