Equivalent & Substitute Parts: BZX55F4V3-TR

Part Overview

The BZX55F4V3-TR is a Zener diode rated at 4.3 V nominal with 500 mW power dissipation, manufactured by Vishay General Semiconductor - Diodes Division. This component is classified as obsolete, though 858 pieces remain in stock as new original inventory. The part is housed in a DO-35 (DO-204AH) axial through-hole package and meets AEC-Q101 automotive qualification standards with ROHS3 compliance.

Due to the obsolete product status, equivalent and substitute parts from active manufacturers are necessary for ongoing design support, production continuity, and long-term component availability. Substitute parts listed below maintain the core electrical specifications while offering active product status and improved availability.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	4.3	V
Power - Max	500	mW
Tolerance	±1%	—
Impedance (Max)	75	Ohms
Current - Reverse Leakage @ Vr	1	µA @ 1 V
Voltage - Forward (Vf) (Max) @ If	1.5	V @ 200 mA
Operating Temperature	175	°C
Package / Case	DO-204AH, DO-35, Axial	—
Mounting Type	Through Hole	—
Grade	Automotive	—
Qualification	AEC-Q101	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the BZX55F4V3-TR is determined by the following critical parameters:

Electrical Compatibility Requirements:

Zener voltage (Vz) must be 4.3 V nominal
Power rating must be 500 mW minimum
Package must be DO-35 (DO-204AH) axial through-hole configuration
Mounting type must be through-hole

Tolerance Considerations: Substitute parts are grouped by zener voltage tolerance specification. The original BZX55F4V3-TR specifies ±1% tolerance. Substitute parts with wider tolerances (±2%, ±5%, ±10%) remain functionally compatible within the 4.3 V specification but exhibit different impedance and leakage characteristics.

Compliance and Status: Active product status is prioritized for long-term availability. ROHS3 compliance and AEC-Q101 automotive qualification are maintained across primary substitute recommendations. RoHS non-compliant alternatives are listed with explicit status notation.

Impedance and Leakage Parameters: Impedance (Zzt) and reverse leakage current vary across substitute options. Lower impedance values (22 Ohms) indicate tighter voltage regulation; higher impedance values (75–90 Ohms) indicate broader tolerance bands. Reverse leakage current ranges from 1 µA to 15 µA depending on manufacturer and tolerance grade.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Ir @ 1V (µA)	Vf @ 200mA (V)	Temp Range (°C)	Status	RoHS
BZX55F4V3-TR	Vishay	4.3	±1%	500	75	1	1.5	—/175	Obsolete	ROHS3
BZX55B4V3-TR	Vishay	4.3	±2%	500	90	1	1.5	-65/175	Active	ROHS3
1N5229B	Taiwan Semiconductor	4.3	±5%	500	22	5	1.1	—/200	Active	ROHS3
1N5229B TR PBFREE	Central Semiconductor	4.3	±5%	500	22	5	1.1	-65/200	Active	ROHS3
1N5229BTR	Fairchild Semiconductor	4.3	—	500	22	5	—	—	Active	—
1N5991A	Microchip Technology	4.3	±10%	500	90	15	1.1	-65/175	Active	Non-compliant
1N5991C	Microchip Technology	4.3	±2%	500	88	5	1.1	-65/175	Active	Non-compliant
1N5991D	Microchip Technology	4.3	±1%	500	88	5	1.1	-65/175	Active	Non-compliant
1N749A TR PBFREE	Central Semiconductor	4.3	±5%	500	22	2	1.5	-65/200	Active	ROHS3

Engineering Selection Recommendations

Primary Substitute (Highest Compatibility): BZX55B4V3-TR from Vishay General Semiconductor is the direct successor within the same manufacturer's product line. It maintains automotive AEC-Q101 qualification, ROHS3 compliance, and active product status. The ±2% tolerance specification represents a minor relaxation from the original ±1%, with impedance increase from 75 Ohms to 90 Ohms. Extended operating temperature range (-65°C to 175°C) provides improved thermal coverage.

Secondary Substitutes (Active Status, ROHS3 Compliant): 1N5229B TR PBFREE (Central Semiconductor) and 1N749A TR PBFREE (Central Semiconductor) both offer active product status with ROHS3 compliance and extended temperature range (-65°C to 200°C). These parts feature lower impedance (22 Ohms) and higher reverse leakage (2–5 µA), suitable for applications requiring tighter voltage regulation. Both are available in cut tape packaging with lead-free construction.

Alternative Substitutes (Active Status, Compliance Considerations): 1N5991C and 1N5991D from Microchip Technology provide active product status with ±2% and ±1% tolerance specifications respectively, matching or exceeding the original tolerance. However, these parts carry RoHS non-compliant status and should be selected only when RoHS3 compliance is not a design requirement. Operating temperature range extends to -65°C to 175°C.

Not Recommended for New Designs: 1N5991A (±10% tolerance) exhibits the widest tolerance band and highest reverse leakage (15 µA), making it unsuitable for precision voltage regulation applications. RoHS non-compliance further limits its applicability in modern designs.

Frequently Asked Questions (FAQ)

Q: Can BZX55B4V3-TR directly replace BZX55F4V3-TR in existing designs?

A: Yes. Both parts share identical zener voltage (4.3 V), power rating (500 mW), and DO-35 package configuration. The tolerance change from ±1% to ±2% and impedance increase from 75 Ohms to 90 Ohms are within acceptable substitution parameters for most applications. Extended temperature range (-65°C to 175°C) provides additional operational margin.

Q: What is the difference between 1N5229B and 1N749A TR PBFREE?

A: Both parts maintain 4.3 V zener voltage and 500 mW power rating in DO-35 packages. Key differences include: 1N5229B exhibits 5 µA reverse leakage and 1.1 V forward voltage at 200 mA; 1N749A TR PBFREE exhibits 2 µA reverse leakage and 1.5 V forward voltage at 200 mA. Both feature 22 Ohms impedance and ±5% tolerance. Selection depends on forward voltage and leakage current requirements for the specific application.

Q: Are Microchip 1N5991 series parts suitable for automotive applications?

A: The 1N5991 series (1N5991A, 1N5991C, 1N5991D) are not qualified to AEC-Q101 automotive standards and carry RoHS non-compliant status. These parts are suitable for industrial and consumer applications where automotive qualification is not required. For automotive designs, select BZX55B4V3-TR, 1N5229B TR PBFREE, or 1N749A TR PBFREE.

Q: What does the "TR PBFREE" designation indicate?

A: "TR" indicates Tape & Reel packaging format suitable for automated assembly. "PBFREE" indicates lead-free construction compliant with RoHS directives. These parts are suitable for high-volume production environments requiring automated component handling and lead-free soldering processes.

Q: How do impedance differences affect circuit performance?

A: Impedance (Zzt) determines the dynamic resistance of the zener diode during voltage regulation. Lower impedance (22 Ohms) provides tighter voltage regulation with smaller voltage variations across load changes. Higher impedance (75–90 Ohms) allows greater voltage variation but may be acceptable in applications with less stringent regulation requirements. Selection depends on the specific voltage regulation tolerance of the circuit design.

Q: Can I use 1N5991A as a substitute despite its ±10% tolerance?

A: 1N5991A is electrically compatible in terms of package and power rating but exhibits the widest tolerance specification (±10%) and highest reverse leakage (15 µA) among available substitutes. Use only in applications where voltage regulation tolerance of ±10% is acceptable. For precision applications requiring ±1% or ±2% tolerance, select BZX55B4V3-TR, 1N5991C, or 1N5991D instead.

Q: What is the operating temperature range difference between substitutes?

A: The original BZX55F4V3-TR specifies maximum operating temperature of 175°C without specified minimum. BZX55B4V3-TR extends the range to -65°C to 175°C. 1N5229B, 1N5229B TR PBFREE, and 1N749A TR PBFREE extend to -65°C to 200°C. Microchip 1N5991 series parts operate from -65°C to 175°C. Select based on the minimum and maximum operating temperatures required by the application environment.

Q: Is ROHS3 compliance mandatory for my application?

A: ROHS3 compliance is mandatory for products sold in the European Union and many other regulated markets. If your design is subject to RoHS directives, select from: BZX55B4V3-TR, 1N5229B, 1N5229B TR PBFREE, or 1N749A TR PBFREE. Microchip 1N5991 series parts are RoHS non-compliant and unsuitable for RoHS-regulated applications.

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