HCPL-4731#320 Equivalent & Substitute Parts

Part Overview

The HCPL-4731#320 is a 2-channel optoisolator with Darlington output, rated for 5000Vrms isolation voltage. Manufactured by Broadcom Limited, this component is classified as obsolete, which necessitates identification of functionally equivalent alternatives for new designs and ongoing production support. The part operates with a current transfer ratio between 600% and 8000% at 500µA input, delivering up to 60mA per channel output with a maximum output voltage of 18V.

Substiute Parts

HCPL-4731#320

Broadcom LimitedIn Stock: 926HCPL-4731#320 Datasheet

Current PartRFQ

HCPL-4731-320E

Broadcom LimitedIn Stock: 875HCPL-4731-320E Datasheet

DirectRFQ

HCPL2730S

Fairchild SemiconductorIn Stock: 2300HCPL2730S Datasheet

MFR RecommendedRFQ

HCPL2730SD

onsemiIn Stock: 4478HCPL2730SD Datasheet

MFR RecommendedRFQ

HCPL2731S

onsemiIn Stock: 1131HCPL2731S Datasheet

MFR RecommendedRFQ

HCPL2731SD

onsemiIn Stock: 3156HCPL2731SD Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the HCPL-4731#320 is determined by the following critical parameters:

Primary Substitution Criteria:

• Number of Channels: 2 (all substitutes maintain this requirement)
• Output Type: Darlington (all substitutes maintain this requirement)
• Mounting Type: Surface Mount, 8-SMD Gull Wing package (all substitutes maintain this requirement)
• Input Type: DC (all substitutes maintain this requirement)

Secondary Substitution Criteria (with allowable variations):

• Voltage - Isolation: Minimum 2500Vrms (HCPL-4731#320 specifies 5000Vrms; lower-rated substitutes are acceptable for applications not requiring full 5000Vrms isolation)
• Current Transfer Ratio: Minimum 300% (HCPL-4731#320 specifies 600% minimum; lower ratios are acceptable for applications with sufficient input current)
• Voltage - Output (Max): Minimum 7V (HCPL-4731#320 specifies 18V maximum; lower ratings are acceptable for applications not requiring full output voltage swing)
• Current - Output / Channel: 60mA (all substitutes maintain this specification)
• Operating Temperature: Extended range acceptable (-40°C ~ 85°C vs. 0°C ~ 70°C)

Substitute Parts Identified:

1. HCPL-4731-320E (Broadcom Limited) — Direct equivalent, active product status
2. HCPL2730S (Fairchild Semiconductor) — Reduced isolation voltage (2500Vrms), active product status
3. HCPL2730SD (onsemi) — Reduced isolation voltage (2500Vrms), obsolete product status
4. HCPL2731S (onsemi) — Reduced isolation voltage (2500Vrms), higher CTR (500%), obsolete product status
5. HCPL2731SD (onsemi) — Reduced isolation voltage (2500Vrms), higher CTR (500%), obsolete product status

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: HCPL-4731-320E

The HCPL-4731-320E is the direct functional equivalent of the HCPL-4731#320. It maintains identical electrical specifications including 5000Vrms isolation voltage, 600-8000% current transfer ratio at 500µA, and 18V maximum output voltage. The critical advantage is active product status, ensuring continued availability and manufacturing support. Additionally, HCPL-4731-320E achieves ROHS3 compliance, addressing regulatory requirements that the original part does not meet. This part is suitable for all applications currently using HCPL-4731#320 without circuit modification.

Secondary Recommendation: HCPL2731SD or HCPL2731S

For applications where 5000Vrms isolation is not required, HCPL2731SD and HCPL2731S provide 2500Vrms isolation with higher current transfer ratio (500% minimum at 1.6mA). Both maintain 18V maximum output voltage and 60mA per-channel current capability. HCPL2731SD offers Cut Tape and Digi-Reel packaging options. Both achieve ROHS3 compliance. These parts are suitable for lower-isolation-voltage applications and provide faster switching response (300ns turn-on vs. 3µs for the original part).

Tertiary Recommendation: HCPL2730S or HCPL2730SD

For applications where 5000Vrms isolation and 18V output voltage are not required, HCPL2730S and HCPL2730SD provide 2500Vrms isolation with 7V maximum output voltage. HCPL2730S maintains active product status. Both achieve ROHS3 compliance and provide faster switching response. These parts are suitable only for applications with reduced output voltage requirements.

Not Recommended for New Designs: HCPL2730SD, HCPL2731S, HCPL2731SD

All three parts carry obsolete product status. While functionally suitable for legacy system maintenance, they should not be selected for new designs due to uncertain long-term availability.

Frequently Asked Questions (FAQ)

Q: Can HCPL-4731-320E be used as a direct replacement for HCPL-4731#320?

A: Yes. HCPL-4731-320E is electrically and mechanically identical to HCPL-4731#320. It maintains the same 5000Vrms isolation voltage, current transfer ratio range (600-8000% at 500µA), output voltage (18V maximum), and 8-SMD Gull Wing package. The primary differences are active product status and ROHS3 compliance.

Q: What is the key difference between HCPL2730S and HCPL2731S?

A: Both parts provide 2500Vrms isolation and 60mA per-channel output current. The primary difference is maximum output voltage: HCPL2730S is rated for 7V maximum, while HCPL2731S is rated for 18V maximum. Additionally, HCPL2731S has a higher minimum current transfer ratio (500% at 1.6mA vs. 300% at 1.6mA for HCPL2730S). HCPL2731S is suitable for applications requiring higher output voltage swing.

Q: Can I use a 2500Vrms-rated part in place of the 5000Vrms HCPL-4731#320?

A: Substitution is possible only if your application does not require 5000Vrms isolation voltage. The reduced isolation rating (2500Vrms) is a permanent design change that affects circuit safety margins and regulatory compliance. Verify that your isolation voltage requirement does not exceed 2500Vrms before selecting HCPL2730S, HCPL2730SD, HCPL2731S, or HCPL2731SD.

Q: What is the packaging difference between HCPL2731S and HCPL2731SD?

A: HCPL2731S is supplied in standard packaging (not specified in detail). HCPL2731SD is supplied in Cut Tape (CT) and Digi-Reel packaging options, which are suitable for automated assembly processes. Both parts are electrically identical.

Q: Why should I avoid obsolete parts like HCPL2730SD and HCPL2731SD for new designs?

A: Obsolete parts carry risk of supply discontinuation. Manufacturers may cease production without notice, making future procurement difficult or impossible. For new designs, HCPL-4731-320E (active status) or HCPL2730S (active status) are preferred to ensure long-term component availability and supply chain stability.

Q: Are all substitute parts ROHS3 compliant?

A: HCPL-4731-320E, HCPL2730SD, HCPL2731S, and HCPL2731SD are ROHS3 compliant. HCPL2730S compliance status is not specified in the provided data. The original HCPL-4731#320 is RoHS non-compliant. If RoHS compliance is a design requirement, select HCPL-4731-320E as the primary choice.

Q: What is the difference in switching speed between the original part and substitutes?

A: HCPL-4731#320 has turn-on/turn-off times of 3µs and 34µs respectively. HCPL2730S, HCPL2730SD, HCPL2731S, and HCPL2731SD all have faster switching times of 300ns turn-on and 5µs turn-off. HCPL-4731-320E maintains the original 3µs and 34µs timing. Select based on your circuit's switching speed requirements.