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P4KE33 Transient Voltage Suppressor (TVS) Equivalent & Substitute Parts
Part Overview
The P4KE33 is a unidirectional transient voltage suppressor diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection applications. This component features a 28.2V reverse standoff voltage with a 400W peak pulse power rating in a through-hole DO-204AL (DO-41) package. The P4KE33 is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. Substitute parts must maintain compatibility across voltage ratings, current handling, package form factors, and thermal operating ranges to ensure functional equivalence in circuit protection applications.
Substiute Parts
Key Parameters
| Parameter | P4KE33 (Main Part) |
|---|---|
| Manufacturer | Littelfuse Inc. |
| Type | Zener TVS Diode |
| Unidirectional Channels | 1 |
| Voltage - Reverse Standoff (Typ) | 28.2V |
| Voltage - Breakdown (Min) | 29.75V |
| Voltage - Clamping (Max) @ Ipp | 47.99V |
| Current - Peak Pulse (10/1000µs) | 9A |
| Power - Peak Pulse | 400W |
| Package / Case | DO-204AL, DO-41, Axial |
| Mounting Type | Through Hole |
| Operating Temperature | -55°C ~ 175°C (TJ) |
| Product Status | Obsolete |
| RoHS Status | ROHS3 Compliant |
Substitute Part Grouping Explanation
Substitution logic for the P4KE33 is based on the following critical parameters:
Primary Substitution Criteria:
- Reverse standoff voltage within the 28.2V nominal range
- Breakdown voltage minimum between 29.75V and 31.4V
- Clamping voltage (Max) @ Ipp between 41.4V and 47.99V
- Peak pulse current capability of 9A or greater
- Peak pulse power rating of 400W or greater
- Through-hole axial package configuration (DO-204AL, DO-41, or equivalent)
- Operating temperature range of -55°C to 175°C or broader
- Unidirectional (single channel) configuration
- General-purpose application suitability
Substitute Categories:
Category 1: Direct Series Equivalents (P4KE Series, DO-204AL Package) Parts maintaining identical package form factor and power rating (400W), with voltage and current parameters within acceptable tolerance bands.
Category 2: Higher Power Alternatives (1.5KE and P6KE Series, DO-201/DO-15 Packages) Parts offering increased power dissipation (600W–1500W) with compatible voltage ratings but different package geometries. These provide enhanced thermal performance for applications requiring greater transient energy absorption.
Category 3: Legacy Equivalents (SA Series, DO-204AC/DO-15 Package) Obsolete series parts with comparable electrical characteristics but different package configurations. Suitable only where mechanical constraints permit package substitution.
Parameter Comparison
| Part Number | Manufacturer | Voltage - Reverse Standoff (Typ) | Voltage - Breakdown (Min) | Voltage - Clamping (Max) @ Ipp | Current - Peak Pulse (10/1000µs) | Power - Peak Pulse | Package / Case | Product Status |
|---|---|---|---|---|---|---|---|---|
| P4KE33 | Littelfuse Inc. | 28.2V | 29.75V | 47.99V | 9A | 400W | DO-204AL (DO-41) | Obsolete |
| P4KE33A | Taiwan Semiconductor Corporation | 28.2V | 31.4V | 45.7V | 9A | 400W | DO-204AL (DO-41) | Active |
| P4KE30A | Taiwan Semiconductor Corporation | 25.6V | 28.5V | 41.4V | 10A | 400W | DO-204AL (DO-41) | Active |
| 1.5KE30A | Taiwan Semiconductor Corporation | 25.6V | 28.5V | 41.4V | 38A | 1500W | DO-201AA (DO-27) | Active |
| 1.5KE33A | Good-Ark Semiconductor | 28.2V | 31.4V | 45.7V | 32.8A | 1500W | DO-201AE | Active |
| P6KE30A | Taiwan Semiconductor Corporation | 25.6V | 28.5V | 41.4V | 14.5A | 600W | DO-204AC (DO-15) | Active |
| P6KE33A | Fairchild Semiconductor | 28.2V | 31.4V | 45.7V | 13.8A | 600W | DO-204AC (DO-15) | Active |
| SA24A | Fairchild Semiconductor | 24V | 26.7V | 38.9V | 13.1A | 500W | DO-204AC (DO-15) | Obsolete |
| SA26A | Fairchild Semiconductor | 26V | 28.9V | 42.1V | 12.1A | 500W | DO-204AC (DO-15) | Obsolete |
| SA26A-B | Littelfuse Inc. | 26V | 28.9V | 42.1V | 12.1A | 500W | DO-204AC (DO-15) | Active |
| SA28A | Fairchild Semiconductor | 28V | 31.1V | 45.4V | 11.2A | 500W | DO-204AC (DO-15) | Obsolete |
Engineering Selection Recommendations
Primary Recommendation: P4KE33A
The P4KE33A from Taiwan Semiconductor Corporation is the optimal direct substitute for the obsolete P4KE33. This part maintains identical package geometry (DO-204AL/DO-41), matching power rating (400W), and equivalent voltage specifications (28.2V reverse standoff, 45.7V clamping). The P4KE33A carries active product status with ROHS3 compliance and unlimited moisture sensitivity rating, ensuring long-term availability and regulatory compliance for new production designs.
Secondary Recommendation: P4KE30A
The P4KE30A provides functional equivalence with a slightly lower reverse standoff voltage (25.6V vs. 28.2V) and marginally improved peak pulse current (10A vs. 9A). This part maintains the same package and power rating, making it suitable for applications where the lower voltage rating is acceptable. Active product status and full compliance certifications support production continuity.
Higher Power Alternatives: 1.5KE33A and P6KE33A
For applications requiring enhanced transient energy absorption, the 1.5KE33A (1500W, DO-201AE) and P6KE33A (600W, DO-15) offer increased power dissipation with matching voltage characteristics (28.2V standoff, 45.7V clamping). These alternatives require mechanical redesign due to different package footprints but provide superior thermal performance. Both maintain active product status and full compliance.
Legacy Alternatives: SA Series
The SA26A-B (active status, Littelfuse Inc.) and SA28A (obsolete) provide functional substitution with comparable voltage and current ratings but in DO-204AC (DO-15) packages. These are suitable only where PCB layout permits package substitution. The SA26A-B offers the advantage of active product status from an established manufacturer.
Compliance and Availability:
All recommended substitutes maintain ROHS3 compliance and operating temperature ranges compatible with the original P4KE33. Inventory availability is confirmed for all active-status parts, supporting immediate procurement for production requirements.
Frequently Asked Questions (FAQ)
Q: Can P4KE33A be used as a direct replacement for P4KE33?
A: Yes. The P4KE33A is a direct substitute with identical package (DO-204AL/DO-41), power rating (400W), and voltage specifications (28.2V standoff, 45.7V clamping). The primary difference is product status: P4KE33A is active while P4KE33 is obsolete. Both are unidirectional zener TVS diodes rated for -55°C to 175°C operation.
Q: What is the difference between P4KE33A and P4KE30A?
A: The P4KE30A has a lower reverse standoff voltage (25.6V vs. 28.2V) and slightly higher peak pulse current (10A vs. 9A). Both share the same package, power rating (400W), and operating temperature range. Selection depends on circuit voltage requirements; P4KE30A is suitable for lower-voltage protection applications.
Q: Can I use 1.5KE33A or P6KE33A instead of P4KE33?
A: Electrically, yes. Both 1.5KE33A and P6KE33A match the 28.2V voltage rating and 45.7V clamping voltage of P4KE33. However, they use different packages (DO-201AE and DO-15 respectively, versus DO-41 for P4KE33). Package substitution requires PCB redesign. The 1.5KE33A and P6KE33A offer higher power ratings (1500W and 600W respectively), providing enhanced transient protection.
Q: Are SA series parts suitable substitutes?
A: SA series parts (SA26A-B, SA28A) provide functional equivalence with comparable voltage and current ratings but use DO-204AC (DO-15) packages instead of DO-41. These are suitable only where mechanical constraints permit package substitution. SA26A-B maintains active product status; SA28A is obsolete.
Q: What does "reverse standoff voltage" mean in the context of TVS diode selection?
A: Reverse standoff voltage is the maximum voltage the TVS diode can withstand in its normal (non-conducting) state without triggering protection. For P4KE33, this is 28.2V. Selecting a substitute requires matching or exceeding this specification to ensure the diode remains inactive during normal circuit operation.
Q: How do I determine if a substitute part is compatible with my circuit?
A: Verify that the substitute part meets or exceeds the following parameters from your original design: reverse standoff voltage, breakdown voltage minimum, clamping voltage maximum, peak pulse current, and power dissipation rating. Package compatibility must also be confirmed; different packages (DO-41 vs. DO-15 vs. DO-27) require different PCB footprints.
Q: Why do some substitutes have higher current ratings (38A for 1.5KE30A vs. 9A for P4KE33)?
A: Higher current ratings indicate greater peak pulse current handling capability, which correlates with larger die size and package geometry. The 1.5KE series uses larger DO-201 packages compared to the DO-41 package of P4KE33. Higher current ratings provide enhanced protection margin but require package-level redesign.
Q: Are all recommended substitutes RoHS compliant?
A: Yes. All active-status substitute parts listed (P4KE33A, P4KE30A, 1.5KE30A, 1.5KE33A, P6KE30A, P6KE33A, SA26A-B) maintain ROHS3 compliance. Obsolete parts (SA26A, SA28A) also carry ROHS3 certification but are no longer in active production.
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