OP775B Phototransistor 935nm Side View Radial Equivalent & Substitute Parts

Part Overview

The OP775B is a 935nm phototransistor manufactured by TT Electronics/Optek Technology, designed for optical sensing applications requiring side view radial configuration. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and new design implementations. The OP775B operates across a wide temperature range (-40°C to 100°C) and is fully RoHS3 compliant with unlimited moisture sensitivity rating.

Substiute Parts

OP775B

TT Electronics/Optek TechnologyIn Stock: 1192OP775B Datasheet

Current PartRFQ

PT908-7C-F

Everlight Electronics Co LtdIn Stock: 45108PT908-7C-F Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the OP775B is determined by the following critical parameters:

• Wavelength Compatibility: The OP775B operates at 935nm. The substitute PT908-7C-F operates at 940nm, representing a 5nm shift within the near-infrared spectrum. Both wavelengths fall within the same optical sensing band for typical infrared applications.
• Electrical Ratings: Both parts maintain identical maximum collector-emitter breakdown voltage (30 V) and dark current specifications (100 nA maximum). The PT908-7C-F provides higher maximum collector current (20 mA vs. 3.4 mA), offering enhanced signal capability.
• Physical Configuration: Both components feature side view radial through-hole mounting, ensuring mechanical compatibility with existing PCB layouts and component footprints.
• Compliance & Certification: Both parts are RoHS3 compliant, REACH unaffected, and carry identical MSL ratings (1 - Unlimited), ensuring regulatory and environmental compatibility.
• Product Status: The OP775B is obsolete; the PT908-7C-F is active production, providing long-term availability assurance.

Parameter Comparison

Engineering Selection Recommendations

The PT908-7C-F serves as the primary substitute for the obsolete OP775B based on the following engineering criteria:

Regulatory Compliance: Both components maintain identical RoHS3 compliance status and REACH unaffected designation, ensuring no regulatory barriers to substitution.

Electrical Compatibility: Matching collector-emitter breakdown voltage (30 V) and dark current specifications (100 nA) establish baseline electrical compatibility. The PT908-7C-F's higher maximum collector current (20 mA) provides operational margin and does not create incompatibility with existing circuit designs rated for the OP775B's 3.4 mA specification.

Physical Compatibility: Identical through-hole radial side view packaging ensures direct mechanical substitution without PCB redesign or component repositioning.

Availability: The PT908-7C-F is in active production with substantial inventory (45,076 pcs), providing long-term supply security compared to the obsolete OP775B status.

Operating Temperature Consideration: The OP775B operates across -40°C to 100°C, while the PT908-7C-F operates across -25°C to 85°C. Applications requiring operation below -25°C or above 85°C must evaluate alternative solutions.

Frequently Asked Questions (FAQ)

Q: Can the PT908-7C-F directly replace the OP775B in existing designs?

A: Yes, for applications operating within the -25°C to 85°C temperature range. The PT908-7C-F maintains identical electrical ratings (30 V breakdown, 100 nA dark current), identical physical configuration (through-hole radial side view), and identical compliance certifications (RoHS3, REACH unaffected). The 5nm wavelength difference (940nm vs. 935nm) is within acceptable tolerance for standard infrared sensing applications.

Q: What is the significance of the wavelength difference between 935nm and 940nm?

A: Both wavelengths operate within the near-infrared spectrum used for optical sensing. The 5nm difference represents a 0.5% variance and does not create functional incompatibility for typical infrared detector applications. Circuit designs should be evaluated for specific spectral sensitivity requirements if wavelength-critical performance is specified.

Q: Does the higher maximum collector current (20 mA vs. 3.4 mA) on the PT908-7C-F affect compatibility?

A: No. The PT908-7C-F's higher maximum rating provides additional operational margin and does not create incompatibility. Existing circuits designed for the OP775B's 3.4 mA specification will operate safely with the PT908-7C-F, which will not exceed the circuit's current demands.

Q: Are there temperature range limitations when substituting the PT908-7C-F?

A: Yes. The PT908-7C-F operates from -25°C to 85°C, compared to the OP775B's -40°C to 100°C range. Applications requiring operation below -25°C or above 85°C must identify alternative components or implement thermal management strategies to maintain operation within the PT908-7C-F's specified range.

Q: What packaging considerations apply to this substitution?

A: Both components use identical through-hole radial side view packaging. No PCB layout modifications, component repositioning, or mechanical redesign is required. Direct pin-for-pin substitution is possible.

Q: Are both components RoHS3 compliant?

A: Yes. Both the OP775B and PT908-7C-F are RoHS3 compliant and REACH unaffected, ensuring regulatory compatibility for applications subject to these standards.