TZX3V9B-TAP Equivalent & Substitute Parts

Part Overview

The TZX3V9B-TAP is a 3.9 V Zener diode rated at 500 mW in a DO-35 through-hole package, manufactured by Vishay General Semiconductor - Diodes Division. This component is classified as an active product with automotive-grade qualification (AEC-Q101) and is RoHS3 compliant. Zener diodes of this specification are used in voltage regulation, overvoltage protection, and reference voltage circuits. Substitute parts may be required due to inventory constraints, supply chain discontinuities, or specific application requirements within the defined electrical and mechanical parameters.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	3.9	V
Power - Maximum	500	mW
Impedance (Maximum)	100	Ohms
Current - Reverse Leakage @ 1 V	5	µA
Voltage - Forward (Maximum) @ 200 mA	1.5	V
Operating Temperature Range	-65 to 175	°C
Mounting Type	Through Hole	-
Package / Case	DO-204AH (DO-35)	-
Grade	Automotive	-
Qualification	AEC-Q101	-

Substitute Part Grouping Explanation

Substitution of the TZX3V9B-TAP is determined by the following critical parameters: nominal Zener voltage (3.9 V), maximum power dissipation capability, package type (DO-35 through-hole), and operating temperature range. All substitute parts listed maintain the 3.9 V nominal Zener voltage specification and through-hole mounting configuration. Substitutes are grouped into two categories based on power rating:

Category 1: 500 mW Rated Substitutes — Parts with 500 mW maximum power dissipation that directly match the TZX3V9B-TAP power specification. These include 1N5228BTR (Fairchild Semiconductor), 1N5228B TR PBFREE (Central Semiconductor Corp), BZX79C3V9 (Taiwan Semiconductor Corporation), and 1N748A-1 (Microchip Technology).

Category 2: 400 mW Rated Substitutes — Parts with 400 mW maximum power dissipation, representing a reduced power capability. These include BZX79-B3V9,113, BZX79-B3V9,133, and BZX79-B3V9,143 (all Nexperia/NXP variants). These substitutes are suitable only for applications where the circuit design accommodates the lower power dissipation limit.

All substitute parts maintain DO-35 package compatibility and through-hole mounting. Zener voltage tolerance, impedance characteristics, and reverse leakage specifications vary among substitutes and must be evaluated against specific circuit requirements.

Parameter Comparison

Parameter	TZX3V9B-TAP	1N5228BTR (Fairchild)	1N5228B TR PBFREE (Central Semi)	1N748A-1 (Microchip)	BZX79C3V9 (Taiwan Semi)	BZX79-B3V9,113 (Nexperia)	BZX79-B3V9,133 (Nexperia)	BZX79-B3V9,143 (NXP)
Voltage - Zener (Nom)	3.9 V	3.9 V	3.9 V	3.9 V	3.9 V	3.9 V	3.9 V	3.9 V
Tolerance	-	±5%	±5%	±5%	±5%	±2%	±2%	±2%
Power - Max	500 mW	500 mW	500 mW	500 mW	500 mW	400 mW	400 mW	400 mW
Impedance (Max)	100 Ohms	23 Ohms	23 Ohms	20 Ohms	90 Ohms	90 Ohms	90 Ohms	90 Ohms
Current - Reverse Leakage @ 1 V	5 µA	10 µA	10 µA	2 µA	10 µA	3 µA	3 µA	3 µA
Voltage - Forward (Max) @ If	1.5 V @ 200 mA	1.2 V @ 200 mA	1.1 V @ 200 mA	1.1 V @ 200 mA	1.5 V @ 100 mA	900 mV @ 10 mA	900 mV @ 10 mA	900 mV @ 10 mA
Operating Temperature	-65 to 175°C	-65 to 200°C	-65 to 200°C	-65 to 175°C	-65 to 175°C	-65 to 200°C	-65 to 200°C	-65 to 200°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	DO-204AH (DO-35)	DO-204AH (DO-35)	DO-204AH (DO-35)	DO-204AH (DO-35)	DO-204AH (DO-35)	DO-204AH (DO-35)	DO-204AH (DO-35)	DO-204AH (DO-35)
RoHS Status	ROHS3 Compliant	Not specified	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	Not specified

Engineering Selection Recommendations

For Direct Replacement (500 mW Power Rating):

The 1N5228BTR (Fairchild Semiconductor) and 1N5228B TR PBFREE (Central Semiconductor Corp) are suitable direct substitutes. Both maintain 500 mW power dissipation, 3.9 V nominal Zener voltage, and DO-35 package compatibility. The 1N5228B TR PBFREE variant is RoHS3 compliant, matching the compliance status of the TZX3V9B-TAP. The 1N5228BTR offers higher inventory availability (30,663 units) compared to the Central Semiconductor variant (7,768 units).

The BZX79C3V9 (Taiwan Semiconductor Corporation) is also a 500 mW substitute with RoHS3 compliance and extended operating temperature range (-65 to 175°C). However, inventory is limited (900 units).

The 1N748A-1 (Microchip Technology) is a 500 mW substitute with superior reverse leakage characteristics (2 µA at 1 V) and lower impedance (20 Ohms). However, this part is RoHS non-compliant, which may restrict use in applications requiring RoHS certification. Inventory is limited (835 units).

For Reduced Power Applications (400 mW Power Rating):

The BZX79-B3V9 series (Nexperia/NXP variants: BZX79-B3V9,113; BZX79-B3V9,133; BZX79-B3V9,143) are suitable only for applications where circuit design accommodates 400 mW maximum power dissipation. These parts offer tighter Zener voltage tolerance (±2% versus unspecified for TZX3V9B-TAP), lower reverse leakage (3 µA at 1 V), and extended operating temperature range (-65 to 200°C). All three variants are RoHS3 compliant. The BZX79-B3V9,143 variant offers the highest inventory (26,056 units).

Compliance Considerations:

For applications requiring AEC-Q101 automotive qualification, the TZX3V9B-TAP is the only part in this list with explicit automotive-grade certification. Substitute parts should be evaluated against specific automotive qualification requirements if applicable.

For RoHS3 compliance requirements, avoid 1N748A-1 (RoHS non-compliant). All other substitutes are RoHS3 compliant or have unspecified compliance status.

Frequently Asked Questions (FAQ)

Q: Can I use a 400 mW rated substitute (BZX79-B3V9 series) in place of the 500 mW TZX3V9B-TAP?

A: Only if your circuit design operates within the 400 mW power dissipation limit. The 400 mW rating represents a lower maximum power capability. If your application requires the full 500 mW dissipation capacity, a 400 mW substitute will not be suitable. Verify circuit power requirements before substitution.

Q: What is the difference between the various BZX79-B3V9 part numbers (113, 133, 143)?

A: These part numbers represent different packaging and supplier configurations of the same electrical specification (3.9 V, 400 mW, ±2% tolerance). BZX79-B3V9,113 and BZX79-B3V9,133 are supplied in Cut Tape (CT) packaging, while BZX79-B3V9,143 is supplied in Bulk packaging. Electrical performance is identical across all three variants.

Q: Is the 1N748A-1 a suitable substitute despite being RoHS non-compliant?

A: The 1N748A-1 is electrically compatible (500 mW, 3.9 V, DO-35 package) but is RoHS non-compliant. Use this part only in applications where RoHS compliance is not required. If your design or end-use application mandates RoHS compliance, select an alternative substitute that is RoHS3 compliant.

Q: How do impedance differences affect substitution?

A: Impedance (Zzt) affects the dynamic resistance of the Zener diode. The TZX3V9B-TAP has 100 Ohms maximum impedance, while substitutes range from 20 to 90 Ohms. Lower impedance provides better voltage regulation under load changes. If your circuit requires specific impedance characteristics for voltage stability, verify that the substitute impedance is acceptable for your application.

Q: Can I substitute based on operating temperature range alone?

A: No. While some substitutes offer extended operating temperature range (-65 to 200°C versus -65 to 175°C for TZX3V9B-TAP), substitution must be based on all critical parameters: Zener voltage, power rating, package type, and impedance. Operating temperature range is one factor among several that determine compatibility.

Q: Are all DO-35 packages physically identical?

A: Yes. All parts listed use the DO-204AH (DO-35) axial through-hole package, which is physically and mechanically identical. This ensures direct board-level compatibility without PCB redesign.

Q: What is the significance of Zener voltage tolerance (±5% versus ±2%)?

A: Tighter tolerance (±2%) provides more precise voltage regulation. The TZX3V9B-TAP has unspecified tolerance, while substitutes range from ±2% to ±5%. If your circuit requires precise voltage reference accuracy, select a substitute with ±2% tolerance (BZX79-B3V9 series). For general voltage regulation applications, ±5% tolerance is typically acceptable.

Q: Why does the 1N5228B TR PBFREE have different forward voltage than 1N5228BTR?

A: Forward voltage (Vf) specifications differ between manufacturers and production batches. The 1N5228B TR PBFREE specifies 1.1 V @ 200 mA while 1N5228BTR specifies 1.2 V @ 200 mA. Both are within acceptable ranges for Zener diode forward conduction. Verify that your circuit design accommodates the specified forward voltage of the selected substitute.

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