P4KE39 Equivalent & Substitute Parts

Part Overview

The P4KE39 is a unidirectional transient voltage suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in through-hole applications. The device features a 33.3V reverse standoff voltage, 56.6V maximum clamping voltage, and 400W peak pulse power rating in a DO-204AL (DO-41) axial package. The P4KE39 is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	33.3	V
Voltage - Breakdown (Min)	35.15	V
Voltage - Clamping (Max) @ Ipp	56.6	V
Current - Peak Pulse (10/1000µs)	7.6	A
Power - Peak Pulse	400	W
Operating Temperature Range	-55 to 175	°C (TJ)
Package / Case	DO-204AL, DO-41, Axial	—
Mounting Type	Through Hole	—
Type	Zener	—
Unidirectional Channels	1	—

Substitute Part Grouping Explanation

Substitute parts for the P4KE39 are grouped into two categories based on electrical and mechanical compatibility:

Category 1: Direct Package Equivalents (DO-204AL / DO-41) These parts maintain the same physical package and mounting footprint as the original P4KE39, enabling direct board-level substitution without layout modifications. Substitution is valid when voltage parameters (reverse standoff, breakdown, and clamping) fall within acceptable tolerance ranges for the application, and current/power ratings meet or exceed the original specification.

Category 2: Higher Power Alternatives (DO-201 / DO-27) These parts use a larger through-hole package with increased power dissipation capability (1500W vs. 400W). Substitution requires mechanical redesign of the PCB footprint and is appropriate only when higher transient energy absorption is required or when the original package is unavailable.

Key Parameters Determining Substitution Validity:

Voltage - Reverse Standoff (Typ): 30.8V to 36.8V range
Voltage - Clamping (Max) @ Ipp: 49.9V to 59.3V range
Current - Peak Pulse (10/1000µs): minimum 7.6A
Power - Peak Pulse: minimum 400W
Operating Temperature: -55°C to 175°C (TJ)
Mounting Type: Through Hole
Unidirectional Channels: 1

Parameter Comparison

Part Number	Manufacturer	Voltage Standoff (V)	Voltage Breakdown Min (V)	Voltage Clamp Max (V)	Current Peak (A)	Power Peak (W)	Package	Status
P4KE39	Littelfuse Inc.	33.3	35.15	56.6	7.6	400	DO-204AL (DO-41)	Obsolete
P4KE39A	Taiwan Semiconductor Corporation	33.3	37.1	53.9	7.7	400	DO-204AL (DO-41)	Active
P4KE39A-AP	Micro Commercial Co	33.3	37.1	53.9	7.6	400	DO-204AL (DO-41)	Active
P4KE39A-BP	Micro Commercial Co	33.3	37.1	53.9	7.6	400	DO-204AL (DO-41)	Active
P6KE36A	Fairchild Semiconductor	30.8	34.2	49.9	12.6	600	DO-204AC (DO-15)	Active
P6KE43A	Diotec Semiconductor	36.8	40.9	59.3	10.6	600	DO-204AC (DO-15)	Active
SA33A	Fairchild Semiconductor	33.0	36.7	53.3	9.4	500	DO-204AC (DO-15)	Obsolete
1.5KE36A	Taiwan Semiconductor Corporation	30.8	34.2	49.9	31	1500	DO-201 (DO-27)	Active
1.5KE39A	Taiwan Semiconductor Corporation	33.3	37.1	53.9	29	1500	DO-201 (DO-27)	Active
1.5KE43A	Taiwan Semiconductor Corporation	36.8	40.9	59.3	26	1500	DO-201 (DO-27)	Active

Engineering Selection Recommendations

Direct Substitutes (No PCB Redesign Required):

P4KE39A, P4KE39A-AP, and P4KE39A-BP are the primary direct substitutes for the obsolete P4KE39. All three maintain identical reverse standoff voltage (33.3V), equivalent clamping voltage (53.9V), matching current ratings (7.6–7.7A), and identical 400W power dissipation in the same DO-204AL (DO-41) package. P4KE39A is manufactured by Taiwan Semiconductor Corporation with Active product status and ROHS3 compliance. P4KE39A-AP and P4KE39A-BP are supplied by Micro Commercial Co with Active status and REACH Unaffected certification. All three are suitable for direct board-level replacement.

Alternative Substitutes (Same Package Family, Different Voltage Ratings):

P6KE36A and P6KE43A are DO-15 (DO-204AC) package alternatives with higher power ratings (600W). These parts maintain through-hole mounting compatibility but require verification of PCB footprint spacing. P6KE36A provides 30.8V standoff voltage with 49.9V clamping and 12.6A peak current. P6KE43A offers 36.8V standoff voltage with 59.3V clamping and 10.6A peak current. Both are Active status with ROHS3 compliance.

Higher Power Alternatives (Requires PCB Redesign):

1.5KE36A, 1.5KE39A, and 1.5KE43A use the larger DO-201 (DO-27) package with 1500W peak power dissipation. These parts require PCB footprint modification but provide significantly higher transient energy absorption. 1.5KE39A matches the original P4KE39 voltage parameters (33.3V standoff, 53.9V clamping) with 29A peak current and Active product status. All three are ROHS3 compliant with REACH Unaffected certification.

Obsolete Alternatives (Not Recommended for New Designs):

SA33A (Fairchild Semiconductor) is classified as Obsolete and should not be selected for new production designs despite matching voltage parameters (33V standoff, 53.3V clamping).

Frequently Asked Questions (FAQ)

Q: Can P4KE39A be used as a direct replacement for P4KE39?

A: Yes. P4KE39A maintains the same reverse standoff voltage (33.3V), equivalent clamping voltage (53.9V), matching current rating (7.7A), and identical 400W power dissipation in the DO-204AL (DO-41) package. No PCB modifications are required.

Q: What is the difference between P4KE39A, P4KE39A-AP, and P4KE39A-BP?

A: All three parts have identical electrical specifications and package. The suffix designates the supplier and packaging format: P4KE39A is the base part number from Taiwan Semiconductor Corporation supplied on tape and reel; P4KE39A-AP and P4KE39A-BP are supplied by Micro Commercial Co in bulk packaging. Electrical performance is equivalent.

Q: Can I use 1.5KE39A instead of P4KE39?

A: 1.5KE39A is electrically compatible (33.3V standoff, 53.9V clamping) but uses a larger DO-201 (DO-27) package requiring PCB footprint redesign. This substitution is appropriate only when higher power dissipation (1500W vs. 400W) is required or when the original package is unavailable.

Q: What are the key voltage parameters I need to verify for substitution?

A: Three voltage parameters determine substitution validity: Voltage - Reverse Standoff (Typ) must remain 33.3V ±3V for the P4KE39 application; Voltage - Clamping (Max) @ Ipp should not exceed 56.6V to prevent circuit overstress; Voltage - Breakdown (Min) must be within 35–37V range to ensure proper device triggering.

Q: Are P6KE36A and P6KE43A compatible with P4KE39?

A: P6KE36A and P6KE43A are compatible from an electrical standpoint but use the DO-15 (DO-204AC) package instead of DO-41 (DO-204AL). Physical verification of PCB footprint spacing is required before substitution. Both parts offer higher power dissipation (600W vs. 400W).

Q: Which substitute part has the highest inventory availability?

A: 1.5KE39A has the highest inventory at 42,000 pieces. P4KE39A has 905 pieces available. For immediate availability in the original package, P4KE39A-BP offers 1,109 pieces.

Q: Are all substitute parts RoHS3 compliant?

A: All active substitute parts listed (P4KE39A, P4KE39A-AP, P4KE39A-BP, P6KE36A, P6KE43A, 1.5KE36A, 1.5KE39A, 1.5KE43A) are ROHS3 compliant. SA33A is also ROHS3 compliant but is classified as Obsolete.

Q: What is the operating temperature range for substitute parts?

A: All substitute parts maintain the same operating temperature range as the original P4KE39: -55°C to 175°C (TJ). P6KE36A and P6KE43A operate from -50°C to 175°C (TJ), a slightly narrower range at the lower temperature limit.

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