1N5366BRL Equivalent & Substitute Parts

Part Overview

The 1N5366BRL is a Zener diode rated for 39 V nominal voltage and 5 W maximum power dissipation in a through-hole axial package (T-18). This component is classified as obsolete by the original manufacturer (onsemi). Equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for new production runs, repairs, and legacy system support. Substitute parts must maintain electrical compatibility across voltage regulation, power handling, and thermal operating ranges.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	39	V
Tolerance	±5%	—
Power - Max	5	W
Impedance (Max)	14	Ohms
Current - Reverse Leakage @ Vr	500 nA @ 29.7 V	—
Voltage - Forward (Vf) (Max) @ If	1.2 V @ 1 A	—
Operating Temperature	-65°C ~ 200°C	—
Mounting Type	Through Hole	—
Package / Case	T-18, Axial	—

Substitute Part Grouping Explanation

Substitute parts for the 1N5366BRL are classified into two categories based on electrical and mechanical compatibility:

Direct Substitutes (Identical Electrical Specifications)

Direct substitutes maintain all critical electrical parameters: 39 V nominal Zener voltage, ±5% tolerance, 5 W maximum power, 14 Ohms maximum impedance, and T-18 axial package configuration. These parts differ only in packaging format (cut tape vs. bulk) or manufacturer source, and are interchangeable without circuit redesign.

Similar Substitutes (Reduced Power or Tolerance Variance)

Similar substitutes share the 39 V nominal Zener voltage and through-hole axial mounting but differ in one or more of the following parameters: maximum power dissipation, voltage tolerance, impedance, or operating temperature range. These parts are suitable for applications where the reduced power rating or tolerance variance does not compromise circuit performance.

Key Parameters Determining Substitution:

Voltage - Zener (Nom): Must equal 39 V
Mounting Type: Must be Through Hole
Package / Case: Must be T-18 Axial or compatible axial format
Power - Max: Direct substitutes require 5 W; similar substitutes may have lower ratings
Tolerance: Direct substitutes require ±5%; similar substitutes may vary
Operating Temperature: Must encompass application requirements

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Vf (Max) @ If	Temp Range	Package	Status
1N5366BRL	onsemi	39 V	±5%	5 W	14 Ω	1.2 V @ 1 A	-65°C ~ 200°C	T-18, Axial	Obsolete
1N5366BRLG	onsemi	39 V	±5%	5 W	14 Ω	1.2 V @ 1 A	-65°C ~ 200°C	T-18, Axial	Active
1N5366B	Microsemi Corporation	39 V	±5%	5 W	14 Ω	1.2 V @ 1 A	-65°C ~ 150°C	T-18, Axial	Active
1N4479	Microchip Technology	39 V	±5%	1.5 W	30 Ω	1.5 V @ 1 A	-65°C ~ 175°C	DO-41, Axial	Active
1N5259	Microchip Technology	39 V	±20%	500 mW	80 Ω	1.5 V @ 200 mA	-65°C ~ 175°C	DO-35, Axial	Active
1N5259B	Microchip Technology	39 V	±5%	500 mW	80 Ω	1.5 V @ 200 mA	-65°C ~ 175°C	DO-35, Axial	Active
1N5366/TR12	Microchip Technology	39 V	±20%	5 W	14 Ω	1.2 V @ 1 A	-65°C ~ 150°C	T-18, Axial	Active
1N5366/TR8	Microchip Technology	39 V	±20%	5 W	14 Ω	1.2 V @ 1 A	-65°C ~ 150°C	T-18, Axial	Active
1N5366A/TR12	Microchip Technology	39 V	±10%	5 W	14 Ω	1.2 V @ 1 A	-65°C ~ 150°C	T-18, Axial	Active
1N5366A/TR8	Microchip Technology	39 V	±10%	5 W	14 Ω	1.2 V @ 1 A	-65°C ~ 150°C	T-18, Axial	Active

Engineering Selection Recommendations

Primary Recommendation: 1N5366BRLG

The 1N5366BRLG is the direct equivalent of the 1N5366BRL. Both parts share identical electrical specifications (39 V, ±5%, 5 W, 14 Ω impedance) and T-18 axial packaging. The 1N5366BRLG is manufactured by onsemi with Active product status and RoHS3 compliance, making it the preferred choice for new designs and production continuity. The only difference is packaging format (cut tape vs. bulk), which does not affect electrical performance.

Secondary Recommendation: 1N5366B

The 1N5366B, manufactured by Microsemi Corporation, provides identical electrical specifications to the 1N5366BRL with the exception of operating temperature range (-65°C ~ 150°C vs. -65°C ~ 200°C). This part is suitable for applications where the maximum operating temperature does not exceed 150°C. The 1N5366B maintains Active product status and is readily available.

Tertiary Recommendations: 1N5366A/TR8 and 1N5366A/TR12

These parts maintain 5 W power rating and T-18 axial packaging with ±10% voltage tolerance (vs. ±5% for the main part). They are suitable for applications where ±10% tolerance is acceptable. Both parts are available in tape and reel packaging and have Active product status.

Alternative Recommendations: 1N5366/TR8 and 1N5366/TR12

These parts maintain 5 W power rating and T-18 axial packaging with ±20% voltage tolerance. They are suitable only for applications where ±20% tolerance is acceptable. Both parts are available in tape and reel packaging and have Active product status.

Lower Power Alternatives: 1N4479, 1N5259, 1N5259B

These parts share the 39 V nominal Zener voltage but have reduced power ratings (1.5 W or 500 mW). The 1N4479 uses DO-41 axial packaging; the 1N5259 and 1N5259B use DO-35 axial packaging. These parts are suitable only for low-power applications where the reduced power dissipation does not compromise circuit performance. The 1N5259 has ±20% tolerance; the 1N5259B has ±5% tolerance.

Frequently Asked Questions (FAQ)

Q: Can I use 1N5366BRLG as a direct replacement for 1N5366BRL?

A: Yes. The 1N5366BRLG is electrically and mechanically identical to the 1N5366BRL. Both parts have 39 V nominal voltage, ±5% tolerance, 5 W power rating, and T-18 axial packaging. The only difference is packaging format (cut tape vs. bulk), which does not affect circuit performance.

Q: What is the difference between 1N5366B and 1N5366BRL?

A: The 1N5366B and 1N5366BRL share identical electrical specifications (39 V, ±5%, 5 W, 14 Ω impedance, T-18 axial package). The primary difference is operating temperature range: 1N5366BRL operates from -65°C to 200°C, while 1N5366B operates from -65°C to 150°C. Select 1N5366B only if your application does not require operation above 150°C.

Q: Can I substitute a lower power Zener diode like 1N5259B for the 1N5366BRL?

A: No, not for applications requiring 5 W power dissipation. The 1N5259B is rated for only 500 mW maximum power, compared to 5 W for the 1N5366BRL. Using an undersized component will result in excessive junction temperature and premature failure. The 1N5259B is suitable only for low-power applications where power dissipation does not exceed 500 mW.

Q: What is the significance of the ±5%, ±10%, and ±20% tolerance ratings?

A: Tolerance specifies the allowable deviation of the Zener voltage from the nominal 39 V rating. ±5% tolerance means the actual voltage will be between 37.05 V and 40.95 V. ±10% tolerance allows 35.1 V to 42.9 V. ±20% tolerance allows 31.2 V to 46.8 V. Select tolerance based on circuit requirements; tighter tolerance (±5%) is required for precision voltage regulation applications.

Q: Why do some substitute parts have different package codes (DO-41, DO-35) instead of T-18?

A: DO-41 and DO-35 are alternative axial package formats with different physical dimensions and thermal characteristics. While all are through-hole axial packages, they have different lead spacing and body sizes. DO-41 and DO-35 packages are not mechanically compatible with T-18 footprints on printed circuit boards. Use these alternatives only if your PCB layout accommodates the different package dimensions.

Q: Is the 1N5366BRL RoHS compliant?

A: No. The 1N5366BRL is classified as RoHS non-compliant. The 1N5366BRLG, the direct equivalent, is RoHS3 compliant and is recommended for new designs subject to RoHS requirements.

Q: What does "Obsolete" product status mean for the 1N5366BRL?

A: Obsolete status indicates that onsemi has discontinued manufacturing the 1N5366BRL. Existing inventory may be available from distributors, but long-term supply is not guaranteed. For new designs and future production, select an active substitute such as 1N5366BRLG or 1N5366B.

Q: Can I use 1N4479 as a substitute if my application only requires low power dissipation?

A: Yes, if your circuit dissipates no more than 1.5 W in the Zener diode. The 1N4479 maintains the 39 V nominal voltage and ±5% tolerance but uses DO-41 axial packaging instead of T-18. Verify that your PCB layout accommodates DO-41 package dimensions before substitution.

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