BZX85B24-TAP Equivalent & Substitute Parts

Part Overview

The BZX85B24-TAP is an automotive-grade Zener diode manufactured by Vishay General Semiconductor - Diodes Division. This through-hole component operates at a nominal Zener voltage of 24 V with a maximum power dissipation of 1.3 W and is housed in a DO-204AL (DO-41) axial package. The device is AEC-Q101 qualified, RoHS3 compliant, and rated for operating temperatures from -55°C to 175°C. The BZX85B24-TAP is currently in active production status with 940 pieces available in inventory.

Equivalent and substitute parts are identified when they share the same nominal Zener voltage (24 V), compatible through-hole axial packaging, and electrical characteristics within acceptable tolerance ranges. Substitutes may vary in maximum power rating, impedance, reverse leakage current, and operating temperature range while maintaining functional compatibility in most circuit applications.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	24	V
Tolerance	±2%	-
Power - Max	1.3	W
Impedance (Max)	25	Ohms
Current - Reverse Leakage @ Vr	500 nA @ 18 V	-
Operating Temperature Range	-55°C to 175°C	-
Mounting Type	Through Hole	-
Package / Case	DO-204AL, DO-41, Axial	-
Grade	Automotive	-
Qualification	AEC-Q101	-
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution of the BZX85B24-TAP is determined by the following critical parameters:

Primary Matching Criteria:

Nominal Zener voltage of 24 V
Through-hole axial mounting configuration
DO-41 or equivalent axial package format
RoHS and REACH compliance status

Secondary Compatibility Factors:

Maximum power dissipation (equal or greater than 1.3 W for direct substitution)
Impedance characteristics (25 Ohms nominal)
Reverse leakage current specifications
Operating temperature range (minimum -55°C to 175°C coverage)
Voltage tolerance (±2% to ±5% acceptable)

The substitute parts listed below maintain the 24 V Zener voltage specification and axial through-hole package format. Variations in power rating, impedance, and leakage current reflect different device series and manufacturers but do not prevent functional substitution in standard voltage regulation and protection circuits. The BZX79-B24,113 operates at reduced power (400 mW) and uses an alternative ALF2 package format, suitable only for lower-power applications.

Parameter Comparison

Parameter	BZX85B24-TAP	1N4749A	1N4749A-T50A	1N4749ATR	1N5934BRNG	BZX79-B24,113
Manufacturer	Vishay	Lumimax	onsemi	Fairchild	onsemi	NXP USA Inc.
Voltage - Zener (Nom)	24 V	24 V	24 V	24 V	24 V	24 V
Tolerance	±2%	±5%	±5%	±5%	±5%	±2%
Power - Max	1.3 W	1 W	1 W	1 W	3 W	400 mW
Impedance (Max)	25 Ohms	25 Ohms	25 Ohms	25 Ohms	19 Ohms	70 Ohms
Current - Reverse Leakage @ Vr	500 nA @ 18 V	5 µA @ 18.2 V	5 µA @ 18.2 V	5 µA @ 18.2 V	1 µA @ 18.2 V	50 nA @ 16.8 V
Operating Temperature	-55°C to 175°C	-65°C to 200°C	-65°C to 200°C	-65°C to 200°C	-65°C to 200°C	-65°C to 200°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	DO-204AL, DO-41	DO-204AL, DO-41	DO-204AL, DO-41	DO-204AL, DO-41	DO-204AL, DO-41	DO-204AH, DO-35
RoHS Status	ROHS3 Compliant	RoHS Compliant	ROHS3 Compliant	Not Specified	ROHS3 Compliant	Not Specified

Engineering Selection Recommendations

Direct Substitutes (1 W Power Rating):

The 1N4749A (Lumimax), 1N4749A-T50A (onsemi), and 1N4749ATR (Fairchild) are functionally equivalent substitutes for the BZX85B24-TAP in applications where the 1.3 W power rating of the original device is not fully utilized. These devices maintain the 24 V nominal Zener voltage, DO-41 axial package format, and 25 Ohms impedance specification. All three operate across an extended temperature range of -65°C to 200°C, exceeding the original -55°C to 175°C specification. The ±5% voltage tolerance is acceptable for most voltage regulation and protection circuits. The 1N4749A-T50A from onsemi carries ROHS3 compliance certification.

Higher Power Substitute (3 W Power Rating):

The 1N5934BRNG (onsemi) provides increased power dissipation capability at 3 W, suitable for applications requiring higher current handling or thermal margin. This device maintains the 24 V Zener voltage and DO-41 package format with improved impedance characteristics (19 Ohms) and lower reverse leakage current (1 µA @ 18.2 V). The extended operating temperature range of -65°C to 200°C and ROHS3 compliance support demanding automotive and industrial applications.

Lower Power Substitute (400 mW Power Rating):

The BZX79-B24,113 (NXP USA Inc.) operates at reduced power dissipation (400 mW) and uses the DO-35 axial package format. This device is suitable only for low-power voltage reference and protection circuits. The ±2% voltage tolerance and lower reverse leakage current (50 nA @ 16.8 V) provide precision voltage regulation. The alternative package format requires PCB layout modification and is not a direct mechanical substitute.

Compliance and Qualification:

All substitute parts maintain RoHS compliance and REACH unaffected status. The BZX85B24-TAP carries AEC-Q101 automotive qualification; substitute parts do not specify automotive qualification but are available in high inventory quantities suitable for production environments.

Frequently Asked Questions (FAQ)

Q: Can the 1N4749A series (1 W) directly replace the BZX85B24-TAP (1.3 W) in all applications?

A: The 1N4749A series maintains the 24 V Zener voltage and DO-41 package compatibility. Direct substitution is valid for applications where power dissipation does not exceed 1 W. Applications requiring the full 1.3 W power rating require the 1N5934BRNG (3 W) or equivalent higher-power device.

Q: What is the difference between the three 1N4749A variants (1N4749A, 1N4749A-T50A, 1N4749ATR)?

A: All three devices share identical electrical specifications (24 V, 1 W, ±5% tolerance, 25 Ohms impedance). Differences exist in packaging format and manufacturer: 1N4749A (Lumimax, standard packaging), 1N4749A-T50A (onsemi, Cut Tape format), and 1N4749ATR (Fairchild, Bulk packaging). Selection depends on procurement requirements and packaging compatibility with assembly processes.

Q: Is the BZX79-B24,113 a suitable substitute for the BZX85B24-TAP?

A: The BZX79-B24,113 maintains the 24 V Zener voltage and ±2% tolerance but operates at 400 mW power dissipation and uses the DO-35 package format instead of DO-41. This device is suitable only for low-power applications and requires PCB layout modification due to package differences. It is not recommended as a general substitute for the BZX85B24-TAP.

Q: What are the key electrical differences between substitute parts?

A: Primary differences include maximum power dissipation (1 W to 3 W range), reverse leakage current (50 nA to 5 µA), and impedance (19 to 70 Ohms). The 1N5934BRNG offers superior power handling and lower leakage. The BZX79-B24,113 provides lower leakage but reduced power capacity. Selection depends on circuit requirements for power dissipation, leakage current tolerance, and impedance characteristics.

Q: Are all substitute parts RoHS3 compliant?

A: The 1N4749A-T50A and 1N5934BRNG explicitly carry ROHS3 compliance certification. The 1N4749A (Lumimax) and 1N4749ATR (Fairchild) specify RoHS compliance without specific version designation. The BZX79-B24,113 does not specify RoHS status. Compliance verification with the specific manufacturer is recommended for regulated applications.

Q: Can substitute parts operate at the full -55°C to 175°C temperature range of the BZX85B24-TAP?

A: All substitute parts operate across -65°C to 200°C, which encompasses and exceeds the original -55°C to 175°C specification. Extended temperature range capability of substitute parts provides additional thermal margin for demanding applications.

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

A: The BZX85B24-TAP and BZX79-B24,113 specify ±2% tolerance, providing tighter voltage regulation accuracy. The 1N4749A series and 1N5934BRNG specify ±5% tolerance, acceptable for most voltage regulation and protection circuits but with wider voltage variation. Applications requiring precision voltage reference should prioritize ±2% tolerance devices.

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