H24B1 Optoisolator Equivalent & Substitute Parts

Part Overview

The H24B1 is an optoisolator with Darlington output manufactured by onsemi, designed for high-voltage isolation applications. It features a 5300Vrms isolation rating and 1000% minimum current transfer ratio at 5mA input. The H24B1 is classified as obsolete, making identification of functionally equivalent substitute components necessary for ongoing system support and new design implementations.

Substiute Parts

H24B1

onsemiIn Stock: 778H24B1 Datasheet

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4N46

Broadcom LimitedIn Stock: 48704N46 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute components for the H24B1 are identified based on the following critical parameters that define functional equivalence:

• Isolation Voltage: Minimum 3750Vrms (H24B1 specifies 5300Vrms)
• Output Type: Darlington or Darlington with Base configuration
• Number of Channels: Single channel (1 channel)
• Input Type: DC input
• Mounting Type: Through Hole
• Package Family: DIP package format
• Current Transfer Ratio: Minimum 200% at specified input current
• Maximum Output Voltage: 20V or higher
• Maximum Forward Current: 20mA or higher

The 4N46 from Broadcom Limited meets these substitution criteria as a functionally equivalent alternative, despite differences in isolation voltage rating, package pin count, and specific electrical characteristics.

Parameter Comparison

Engineering Selection Recommendations

The 4N46 is an active product from Broadcom Limited and represents the primary substitute for the obsolete H24B1. Both components share identical regulatory compliance classifications (RoHS non-compliant, REACH Unaffected, EAR99 ECCN) and moisture sensitivity ratings.

Key considerations for substitution:

• The 4N46 provides lower isolation voltage (3750Vrms versus 5300Vrms). Applications requiring the full 5300Vrms isolation specification cannot use this substitute.
• The 4N46 package is 6-DIP versus the H24B1's 4-DIP format, requiring PCB layout modification and pin mapping verification.
• The 4N46 output stage includes a base connection, enabling additional circuit design flexibility not available with the H24B1's standard Darlington output.
• Maximum output voltage of the 4N46 is 20V compared to 30V for the H24B1, limiting applications requiring higher switching voltages.
• Maximum forward current rating differs (20mA for 4N46 versus 60mA for H24B1), affecting input drive circuit design.

Frequently Asked Questions (FAQ)

Q: Can the 4N46 directly replace the H24B1 without PCB modifications?

A: No. The 4N46 uses a 6-DIP package while the H24B1 uses 4-DIP. Pin count and spacing differ, requiring PCB layout changes and verification of pin function mapping before substitution.

Q: What is the primary limitation of using the 4N46 as a substitute?

A: The 4N46 provides 3750Vrms isolation voltage compared to the H24B1's 5300Vrms. Applications with isolation voltage requirements exceeding 3750Vrms cannot use this substitute.

Q: Are there compliance or regulatory differences between the H24B1 and 4N46?

A: No. Both components share identical RoHS status (non-compliant), REACH status (Unaffected), and ECCN classification (EAR99). Moisture sensitivity levels are also identical at MSL 1 (Unlimited).

Q: How do the current transfer ratios compare?

A: The H24B1 specifies 1000% minimum at 5mA input. The 4N46 specifies 200% minimum at 10mA input, with a maximum of 1000% at 10mA. Input current requirements differ between the two components.

Q: What is the significance of the base connection on the 4N46?

A: The 4N46 Darlington output includes a base connection, allowing external base drive control. The H24B1 standard Darlington output does not provide this connection, limiting circuit design options.

Q: Are both components suitable for new designs?

A: The H24B1 is obsolete and unsuitable for new designs. The 4N46 is active and appropriate for new applications meeting its electrical and package specifications.