3KP40A-B Transient Voltage Suppressor (TVS) Diode - Equivalent & Substitute Parts

Part Overview

The 3KP40A-B is a unidirectional Zener-type transient voltage suppressor manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This through-hole axial component operates across a temperature range of -55°C to 175°C and is ROHS3 compliant with unlimited moisture sensitivity rating (MSL 1).

The 3KP40A-B is classified as obsolete, making identification of functionally equivalent substitute parts essential for ongoing design support and procurement. Substitute parts must maintain electrical compatibility across voltage standoff, breakdown, clamping characteristics, and thermal operating range while accommodating different packaging formats and power ratings.

Substiute Parts

3KP40A-B

Littelfuse Inc.In Stock: 7443KP40A-B Datasheet

Current PartRFQ

5KP40A-B

Littelfuse Inc.In Stock: 11615KP40A-B Datasheet

DirectRFQ

15KP40A-TP

Micro Commercial CoIn Stock: 107315KP40A-TP Datasheet

MFR RecommendedRFQ

3KP40A-TP

Micro Commercial CoIn Stock: 7783KP40A-TP Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 3KP40A-B are qualified based on the following electrical and mechanical compatibility criteria:

Primary Compatibility Parameters:

• Voltage - Reverse Standoff: 40V (exact match required)
• Voltage - Breakdown (Min): 44.4V (exact match required)
• Voltage - Clamping (Max) @ Ipp: 64.5V or within acceptable tolerance
• Operating Temperature Range: -55°C to 175°C (minimum requirement)
• Type: Zener, Unidirectional (1 channel)
• Mounting Type: Through Hole
• RoHS Compliance: ROHS3 Compliant

Secondary Considerations:

• Current - Peak Pulse: May vary based on power rating and application requirements
• Power - Peak Pulse: Higher ratings provide enhanced transient protection capability
• Package / Case: Physical form factor may differ (P600 vs. R-6) but must maintain through-hole axial configuration
• Product Status: Active status preferred for long-term availability

Three substitute parts meet these criteria with varying power ratings and packaging configurations.

Parameter Comparison

Engineering Selection Recommendations

5KP40A-B (Littelfuse Inc.) — Direct electrical equivalent with enhanced power rating. Maintains identical voltage parameters (40V standoff, 44.4V breakdown, 64.5V clamping) and current specification (46.5A peak pulse). Rated for 5000W peak pulse versus 3000W for the original part. Active product status ensures long-term availability. P600 axial package matches original form factor. Suitable for direct replacement in applications where higher transient energy absorption is acceptable or beneficial.

15KP40A-TP (Micro Commercial Co) — Manufacturer-recommended substitute with significantly elevated power rating (15000W). Maintains voltage compatibility (40V standoff, 44.4V breakdown) with marginally higher clamping voltage (65.8V vs. 64.5V). Packaged in R-6 axial configuration requiring mechanical board layout verification. Active product status with REACH compliance. Appropriate for applications requiring maximum transient protection or where design margins justify the higher power rating.

3KP40A-TP (Micro Commercial Co) — Electrical equivalent with identical power rating (3000W) and current specification (46.5A peak pulse). Maintains all voltage parameters matching the original part. Packaged in R-6 axial format. Active product status. Represents a direct functional replacement with alternative packaging geometry.

All three substitutes maintain ROHS3 compliance, unlimited MSL rating, and full operating temperature range compatibility (-55°C to 175°C).

Frequently Asked Questions (FAQ)

Q: Can 5KP40A-B replace 3KP40A-B in any application?

A: Yes, from an electrical standpoint. The 5KP40A-B maintains identical voltage characteristics (40V standoff, 44.4V breakdown, 64.5V clamping) and current rating (46.5A peak pulse). The higher power rating (5000W vs. 3000W) provides additional transient energy absorption capability without compromising circuit protection. Physical form factor (P600 axial) remains unchanged. Verify board layout and thermal management accommodate the component.

Q: What is the difference between 15KP40A-TP and 3KP40A-B?

A: Both maintain the same 40V reverse standoff voltage and 44.4V breakdown voltage. The 15KP40A-TP provides significantly higher power dissipation (15000W vs. 3000W) and uses an R-6 axial package instead of P600. The clamping voltage is marginally higher (65.8V vs. 64.5V). Selection depends on application transient energy requirements and available board space for the different package geometry.

Q: Are all substitutes through-hole components?

A: Yes. The 3KP40A-B and all listed substitutes are through-hole mounted axial devices. Package variants include P600 (original and 5KP40A-B) and R-6 (15KP40A-TP and 3KP40A-TP). Both package types maintain through-hole axial configuration suitable for PCB insertion.

Q: Do substitute parts maintain the same operating temperature range?

A: Yes. All substitute parts operate across -55°C to 175°C (TJ), matching the original 3KP40A-B specification. This ensures thermal compatibility in applications with extended temperature requirements.

Q: Why is 3KP40A-B listed as obsolete?

A: The 3KP40A-B is classified as obsolete by Littelfuse Inc. Active alternatives (5KP40A-B from Littelfuse and 3KP40A-TP from Micro Commercial Co) provide equivalent electrical performance with assured long-term availability. The 15KP40A-TP offers enhanced protection capability for new designs.

Q: Are all substitutes ROHS3 compliant?

A: Yes. The 3KP40A-B and all three substitute parts carry ROHS3 compliance certification, meeting environmental and regulatory requirements for electronic component manufacturing and use.