Phototransistor Die: Isolation Voltage 1500-5000Vrms

Component Specifications

Definition

A phototransistor die is the semiconductor core of a phototransistor, typically fabricated from silicon or other semiconductor materials. It functions as a light-sensitive transistor where incident photons generate electron-hole pairs in the base region, amplifying the photocurrent through transistor action. This component is the critical element in photocouplers/optoisolators, providing electrical isolation between circuits while transmitting signals via light.

Working Principle

Operates on the photoelectric effect combined with bipolar transistor amplification. When light strikes the base-collector junction, photons generate electron-hole pairs, creating a base current proportional to light intensity. This current is amplified by the transistor's current gain (β), producing a larger collector current output. In photocoupler assemblies, an LED emits light onto the phototransistor die, creating an isolated signal path.

Materials

Silicon (Si) semiconductor substrate with doped regions (N-type and P-type), silicon dioxide (SiO₂) passivation layers, aluminum or gold metallization for contacts, and sometimes epoxy encapsulation in final assembly.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Package Type	Surface-mount (SMD) or through-hole
Rise/Fall Time	2-15μs
Isolation Voltage	1500-5000Vrms
Collector Current (Ic)	10-100mA
Wavelength Sensitivity	400-1100 nm (peak around 850-950 nm)
Current Transfer Ratio (CTR)	20-600%
Collector Emitter Voltage (Vceo)	30-80V

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

IEC 60747-5-2, JEDEC JESD22

Parent Products

This component is used in the following industrial products

Photocoupler Assembly

A complete assembly containing the core photocoupler device and its supporting electrical/mechanical elements, designed for integration into an isolation barrier system.

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Engineering Analysis

Risks & Mitigation

ESD sensitivity during handling
Contamination affecting light sensitivity
Thermal runaway at high currents
Degradation from prolonged UV exposure

FMEA Triads

Trigger: Electrostatic discharge (ESD) during assembly
Failure: Permanent damage to semiconductor junctions
Mitigation: Implement ESD-protected workstations, proper grounding, and handling procedures

Trigger: Moisture ingress in packaging
Failure: Corrosion of metallization, reduced reliability
Mitigation: Use hermetic sealing or moisture-resistant encapsulants, follow IPC moisture sensitivity levels

Trigger: Excessive forward current in driving LED
Failure: Premature aging, reduced CTR over time
Mitigation: Implement current limiting circuits, derate operating parameters

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±10% on CTR, ±5nm on spectral response

Test Method

IEC 60747-5-2 for optoelectronic devices, including light-current characteristics, isolation voltage testing, and environmental stress testing

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of Phototransistor Die

Manufacturer profiles associated with Phototransistor Die.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What is the difference between a phototransistor die and a photodiode?

A phototransistor die provides internal current amplification (gain) through transistor action, making it more sensitive than a photodiode which has no amplification. Phototransistors have slower response times but higher output current for given light levels.

How does temperature affect phototransistor die performance?

Temperature increases dark current (leakage) and can reduce current transfer ratio (CTR). Proper thermal design and derating are essential for stable operation in industrial environments.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Phototransistor Die