1N5226B-T Zener Diode Equivalent & Substitute Parts

Part Overview

The 1N5226B-T is a 3.3 V zener diode rated at 500 mW with ±5% tolerance, manufactured by Diodes Incorporated in a DO-35 through-hole package. This component is classified as obsolete, though 1021 pieces remain in stock as new original inventory. The part is ROHS3 compliant and operates across a temperature range of -65°C to 200°C.

Due to the obsolete status of the 1N5226B-T, equivalent and substitute parts from active manufacturers are necessary for new designs and long-term supply chain continuity. Substitute parts maintain the core electrical specifications while offering availability from manufacturers with active product lines.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	3.3	V
Tolerance	±5%	—
Power - Maximum	500	mW
Impedance (Maximum)	28	Ohms
Current - Reverse Leakage @ Vr	25	µA @ 1 V
Voltage - Forward (Maximum) @ If	1.1	V @ 200 mA
Operating Temperature Range	-65 to 200	°C
Mounting Type	Through Hole	—
Package / Case	DO-204AH, DO-35, Axial	—

Substitute Part Grouping Explanation

Substitution of the 1N5226B-T is determined by the following critical parameters:

Primary Electrical Specifications:

Zener voltage: 3.3 V (nominal)
Power dissipation: 500 mW
Tolerance: ±5% (preferred) or ±10% (acceptable with design margin verification)
Impedance: 28 Ohms (nominal specification)

Physical and Mounting Requirements:

Package type: DO-35 (DO-204AH) through-hole axial configuration
Lead compatibility: Axial leads for through-hole PCB mounting

Environmental and Compliance Criteria:

Operating temperature range: -65°C to 200°C (or -65°C to 175°C minimum)
RoHS compliance status (ROHS3 preferred for new designs)

Substitute parts are grouped into two categories:

Category 1: Direct Electrical and Package Equivalents (500 mW, DO-35) Parts maintaining identical power rating, voltage, tolerance, and package format. These include 1N5226B variants from multiple manufacturers and 1N746A TR PBFREE.

Category 2: Higher Power Alternative (1 W, DO-41) The 1N4728ATR provides increased power dissipation (1 W) in a larger DO-41 package. This part is suitable only when PCB layout accommodates the larger package and higher power capability is beneficial.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Vf @ 200mA (V)	Temp Range (°C)	Package	Status	RoHS
1N5226B-T	Diodes Incorporated	3.3	±5%	500	28	1.1	-65 to 200	DO-35	Obsolete	ROHS3
1N5226A	Microsemi Corporation	3.3	±10%	500	28	1.5	-65 to 175	DO-35	Active	Non-compliant
1N5226B	Microchip Technology	3.3	±5%	500	28	1.5	-65 to 175	DO-35	Active	Non-compliant
1N5226B BK PBFREE	Central Semiconductor Corp	3.3	±5%	500	28	1.1	-65 to 200	DO-35	Active	ROHS3
1N5226BTR	Fairchild Semiconductor	3.3	±5%	500	28	1.2	-65 to 200	DO-35	Active	—
1N746A TR PBFREE	Central Semiconductor Corp	3.3	±5%	500	28	1.5	-65 to 200	DO-35	Active	ROHS3
1N5226A	Microchip Technology	3.3	±10%	500	28	1.5	-65 to 175	DO-35	Active	Non-compliant
1N5226B	Microsemi Corporation	3.3	±5%	500	28	1.5	-65 to 175	DO-35	Active	Non-compliant
BZX79C3V3	Taiwan Semiconductor Corporation	3.3	±5%	500	95	1.5	-65 to 175	DO-35	Active	ROHS3
1N4728ATR	Fairchild Semiconductor	3.3	±5%	1000	10	—	-65 to 200	DO-41	Active	—

Engineering Selection Recommendations

For Direct Replacement (500 mW, DO-35 Package):

Tier 1 - Preferred Substitutes (Highest Compatibility):

1N5226B BK PBFREE (Central Semiconductor Corp): Maintains ±5% tolerance, 500 mW power rating, DO-35 package, and extended temperature range (-65°C to 200°C). ROHS3 compliant. Forward voltage specification (1.1 V @ 200 mA) matches the original part exactly.
1N5226BTR (Fairchild Semiconductor): Meets all electrical specifications with ±5% tolerance, 500 mW, and -65°C to 200°C operating range. Active product status with high inventory availability (55,759 pieces).

Tier 2 - Compatible Substitutes (Minor Parameter Variations):

1N5226B (Microchip Technology or Microsemi Corporation): Maintains ±5% tolerance and 500 mW rating in DO-35 package. Operating temperature range limited to -65°C to 175°C. Forward voltage specification differs (1.5 V @ 200 mA). Suitable for applications not requiring the full 200°C upper temperature limit.
1N746A TR PBFREE (Central Semiconductor Corp): Equivalent electrical specifications with ±5% tolerance and 500 mW. Extended temperature range (-65°C to 200°C). ROHS3 compliant. Reverse leakage current specification differs (10 µA @ 1 V versus 25 µA).

Tier 3 - Acceptable Substitutes (Tolerance Trade-off):

1N5226A (Microsemi Corporation or Microchip Technology): Provides 500 mW in DO-35 package with relaxed ±10% tolerance. Operating temperature range -65°C to 175°C. Suitable for applications where ±10% zener voltage tolerance is acceptable and full temperature range is not required.

Alternative for Higher Power Applications:

1N4728ATR (Fairchild Semiconductor): Provides 3.3 V zener voltage with doubled power dissipation (1 W) in a larger DO-41 package. Impedance reduced to 10 Ohms. Suitable only when PCB layout accommodates the larger package and higher power capability is required or beneficial for thermal margin.

Compliance Considerations:

For new designs requiring ROHS3 compliance, select from: 1N5226B BK PBFREE, 1N746A TR PBFREE, or BZX79C3V3.
For applications with RoHS non-compliance acceptable, 1N5226B variants from Microchip Technology or Microsemi Corporation offer active product status.

Frequently Asked Questions (FAQ)

Q: Can I use 1N5226A as a direct replacement for 1N5226B-T?

A: The 1N5226A is functionally compatible but with design considerations. The tolerance is relaxed to ±10% compared to ±5% on the original part. The operating temperature range is limited to -65°C to 175°C versus -65°C to 200°C. Forward voltage is specified at 1.5 V @ 200 mA instead of 1.1 V. Use this part only if your circuit design accommodates the wider tolerance and lower maximum temperature specification.

Q: What is the difference between 1N5226B and 1N746A TR PBFREE?

A: Both parts are 3.3 V, 500 mW zener diodes in DO-35 packages with ±5% tolerance. The 1N746A TR PBFREE has a lower reverse leakage current specification (10 µA @ 1 V versus 25 µA @ 1 V) and is supplied in cut tape packaging. Both support the full -65°C to 200°C temperature range. The 1N746A TR PBFREE is ROHS3 compliant.

Q: Why does BZX79C3V3 have a higher impedance (95 Ohms) than the original part (28 Ohms)?

A: The BZX79C3V3 is a different zener diode series from Taiwan Semiconductor Corporation with different internal characteristics. While it maintains the same 3.3 V nominal voltage, 500 mW power rating, and ±5% tolerance, the higher impedance reflects different semiconductor design. This part is suitable for applications where impedance variation is not critical to circuit performance.

Q: Can I use the 1N4728ATR (1 W) instead of the 1N5226B-T (500 mW)?

A: The 1N4728ATR is electrically compatible with the same 3.3 V zener voltage and ±5% tolerance. However, it uses a larger DO-41 package instead of DO-35, requiring different PCB footprint and lead spacing. The 1 W power rating provides additional thermal margin but is not necessary for applications designed for 500 mW. Use this part only if your PCB layout accommodates the larger package and the increased power capability is beneficial.

Q: What does ROHS3 compliance mean for this zener diode?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead, cadmium, mercury, hexavalent chromium, and certain flame retardants. For new designs, ROHS3 compliant parts (1N5226B BK PBFREE, 1N746A TR PBFREE, BZX79C3V3) are recommended to ensure regulatory compliance in most markets.

Q: Are all substitute parts available in the same packaging format?

A: All recommended substitutes in Tier 1 and Tier 2 use the DO-35 through-hole axial package, maintaining identical PCB footprint compatibility. The 1N4728ATR alternative uses DO-41 packaging, which requires a different footprint. Verify packaging format before selection.

Q: What is the significance of the forward voltage (Vf) specification difference?

A: Forward voltage specification indicates the voltage drop across the diode when conducting in the forward direction. The original 1N5226B-T specifies 1.1 V @ 200 mA, while some substitutes specify 1.5 V @ 200 mA. This difference affects circuit behavior only if the diode conducts in forward bias mode. For typical zener diode applications (reverse bias voltage regulation), forward voltage specification is not critical.

Q: Which substitute offers the best inventory availability?

A: The 1N5226BTR from Fairchild Semiconductor offers the highest inventory availability with 55,759 pieces in stock. The 1N746A TR PBFREE from Central Semiconductor Corp provides 16,293 pieces. Both parts are active products with substantial supply.

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