H11A3 Optoisolator Equivalent & Substitute Parts

Part Overview

The H11A3 is an optoisolator transistor with base output manufactured by Everlight Electronics Co Ltd, designed for galvanic isolation applications requiring 5000Vrms isolation voltage. This component features a single-channel configuration with transistor output and integrated base connection, housed in a 6-DIP through-hole package.

The H11A3 is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support legacy system maintenance and repairs.

Substiute Parts

H11A3

Everlight Electronics Co LtdIn Stock: 1472H11A3 Datasheet

Current PartRFQ

4N38

onsemiIn Stock: 73714N38 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the H11A3 optoisolator is determined by the following critical parameters:

Mandatory Matching Criteria:

• Package / Case: 6-DIP (0.300", 7.62mm) — ensures mechanical and electrical compatibility with existing PCB layouts
• Number of Channels: 1 — maintains functional equivalence
• Output Type: Transistor with Base — preserves circuit interface requirements
• Mounting Type: Through Hole — ensures installation compatibility
• Input Type: DC — maintains signal compatibility

Functional Compatibility Criteria:

• Voltage - Isolation: minimum 5000Vrms — substitute must meet or exceed isolation specification
• Current Transfer Ratio (Min): 20% @ 10mA — substitute must achieve minimum specified gain
• Voltage - Output (Max): 80V — substitute must support maximum output voltage requirement
• Operating Temperature Range: must encompass or exceed -55°C ~ 110°C

The 4N38 manufactured by onsemi meets all mandatory matching criteria and functional compatibility requirements, qualifying it as a direct substitute for the H11A3.

Parameter Comparison

Engineering Selection Recommendations

Substitution Feasibility:

The 4N38 optoisolator from onsemi is a qualified substitute for the H11A3. Both components share identical package geometry, channel configuration, output type, and minimum current transfer ratio specifications. Both are classified as obsolete products with MSL Level 1 rating.

Performance Considerations:

The 4N38 provides enhanced isolation voltage (5300Vrms versus 5000Vrms), supporting higher voltage isolation margins. The 4N38 specifies maximum output current of 100mA, compared to the H11A3's unspecified output current rating. The 4N38 exhibits slightly lower forward voltage (1.15V versus 1.2V) and higher forward current rating (80mA versus 60mA).

The H11A3 demonstrates faster switching characteristics (3µs turn-on/off versus 5µs) and lower Vce saturation voltage (400mV versus 1V). The H11A3 supports extended operating temperature to 110°C, while the 4N38 operates to 100°C maximum.

Compliance Status:

The H11A3 is confirmed ROHS3 compliant. The 4N38 RoHS compliance status is not specified in available data. Both components carry EAR99 ECCN classification and identical HTSUS codes (8541.49.8000).

Selection Guidance:

Applications requiring maximum switching speed or extended high-temperature operation (-55°C to 110°C) should retain the H11A3 if available. Applications tolerating slightly slower switching (5µs) and maximum 100°C operation can implement the 4N38 as a direct substitute. Circuit designs requiring higher output current capacity (100mA) benefit from 4N38 selection.

Frequently Asked Questions (FAQ)

Q: Can the 4N38 directly replace the H11A3 in existing PCB designs?

A: Yes. Both components use identical 6-DIP (0.300", 7.62mm) through-hole packaging. Pin-to-pin compatibility is maintained for single-channel transistor-output optoisolators. No PCB layout modifications are required.

Q: What are the key differences between H11A3 and 4N38?

A: The 4N38 provides higher isolation voltage (5300Vrms versus 5000Vrms) and specified output current (100mA). The H11A3 offers faster switching speed (3µs versus 5µs) and lower saturation voltage (400mV versus 1V). The H11A3 supports higher maximum operating temperature (110°C versus 100°C).

Q: Are both parts still available for purchase?

A: Both H11A3 and 4N38 are classified as obsolete. Availability depends on distributor inventory. The 4N38 typically has higher stock levels due to broader historical adoption.

Q: Does the 4N38 meet RoHS compliance requirements?

A: The H11A3 is confirmed ROHS3 compliant. The 4N38 RoHS compliance status is not specified in the provided technical data. Verify RoHS certification with the component supplier before final selection for regulated applications.

Q: What applications are affected by the switching speed difference?

A: Applications operating at frequencies above 100 kHz may experience performance differences due to the 2µs switching speed differential (H11A3: 3µs versus 4N38: 5µs). High-frequency pulse-width modulation circuits and fast logic-level switching applications should evaluate this parameter.

Q: Can I use the 4N38 in high-temperature environments?

A: The 4N38 maximum operating temperature is 100°C. Applications requiring operation above 100°C must use the H11A3 (rated to 110°C). Verify actual circuit operating temperature against component specifications.

Q: Is base connection functionality identical between both parts?

A: Yes. Both H11A3 and 4N38 feature transistor output with base connection. Base drive characteristics and external base resistor requirements should be verified against specific circuit design parameters.