BZX55C11 Equivalent & Substitute Parts

Part Overview

The BZX55C11 is a Zener diode rated at 11 V nominal voltage with 500 mW power dissipation, manufactured by onsemi in the DO-35 through-hole package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The BZX55C11 operates across a temperature range of -65°C to 200°C and maintains ±5% voltage tolerance, suitable for voltage regulation and protection applications in electronic circuits.

Key Parameters

Parameter	Value
Voltage - Zener (Nom)	11 V
Tolerance	±5%
Power - Max	500 mW
Impedance (Max)	20 Ohms
Current - Reverse Leakage @ Vr	100 nA @ 8.5 V
Voltage - Forward (Vf) (Max) @ If	1.3 V @ 100 mA
Operating Temperature	-65°C ~ 200°C
Mounting Type	Through Hole
Package / Case	DO-204AH, DO-35, Axial
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the BZX55C11 is determined by strict alignment of electrical and mechanical parameters. The primary criteria for equivalence are:

Critical Parameters for Substitution:

Zener voltage: 11 V nominal
Voltage tolerance: ±5%
Power rating: 500 mW (direct equivalents) or 400 mW (reduced power alternatives)
Package type: DO-35 through-hole
Impedance: 20 Ohms maximum
Operating temperature range: -65°C minimum to 175°C or higher

Direct Equivalents maintain all electrical specifications including 500 mW power rating and identical impedance characteristics. These parts are interchangeable without circuit redesign.

Parametric Equivalents meet the core voltage and tolerance requirements with matching impedance and temperature ranges, differing only in packaging format (tape & reel versus cut tape).

Similar Parts share the same 11 V nominal voltage and ±5% tolerance but operate at reduced power levels (400 mW) and may use alternative package designations (ALF2). These require circuit evaluation to confirm suitability for the intended application.

Parameter Comparison

Part Number	Manufacturer	Product Status	Vz (Nom)	Tolerance	Power - Max	Zzt (Max)	Vf (Max) @ If	Temp Range	Package
BZX55C11	onsemi	Obsolete	11 V	±5%	500 mW	20 Ohms	1.3 V @ 100 mA	-65°C ~ 200°C	DO-35
1N5241B	Microchip Technology	Active	11 V	±5%	500 mW	22 Ohms	1.5 V @ 200 mA	-65°C ~ 175°C	DO-35
BZX79C11-T50A	onsemi	Active	11 V	±5%	500 mW	20 Ohms	1.5 V @ 100 mA	-65°C ~ 200°C	DO-35
BZX79C11	Taiwan Semiconductor Corporation	Active	11 V	±5%	500 mW	20 Ohms	1.5 V @ 100 mA	-65°C ~ 175°C	DO-35
BZX79-C11,113	Nexperia USA Inc.	Active	11 V	±5%	400 mW	20 Ohms	900 mV @ 10 mA	-65°C ~ 200°C	ALF2
BZX79-C11,133	Nexperia USA Inc.	Active	11 V	±5%	400 mW	20 Ohms	900 mV @ 10 mA	-65°C ~ 200°C	ALF2
BZX79-C11,143	NXP Semiconductors	Active	11 V	±5%	400 mW	20 Ohms	900 mV @ 10 mA	-65°C ~ 200°C	ALF2

Engineering Selection Recommendations

Direct Replacement (Active Status):

The BZX79C11-T50A (onsemi) and BZX79C11 (Taiwan Semiconductor Corporation) are the primary active alternatives to the obsolete BZX55C11. Both maintain the 11 V nominal voltage, ±5% tolerance, 500 mW power rating, and 20 Ohms impedance. The BZX79C11-T50A extends the upper operating temperature to 200°C, matching the original part specification. Both parts are RoHS3 compliant and REACH unaffected, meeting current regulatory requirements.

The 1N5241B (Microchip Technology) provides an active alternative with identical voltage and power specifications. The impedance increases to 22 Ohms and the maximum operating temperature reduces to 175°C. This part is suitable for applications where the reduced temperature range and slightly higher impedance do not impact circuit performance.

Reduced Power Alternatives:

The BZX79-C11,113, BZX79-C11,133, and BZX79-C11,143 variants operate at 400 mW maximum power, representing a 20% reduction from the original 500 mW specification. These parts maintain the 11 V voltage and ±5% tolerance with identical 20 Ohms impedance. All three are RoHS3 compliant and REACH unaffected. Selection among these variants depends on packaging availability and supplier preference, as electrical characteristics are equivalent. These parts are suitable only for applications where the reduced power dissipation capacity does not exceed circuit requirements.

Compliance and Availability:

All substitute parts listed carry REACH unaffected status and EAR99 ECCN classification, matching the original part's regulatory profile. Active status parts ensure ongoing availability and manufacturing support, eliminating obsolescence concerns associated with the BZX55C11.

Frequently Asked Questions (FAQ)

Q: Can the 1N5241B directly replace the BZX55C11 in all applications?

A: The 1N5241B maintains the critical 11 V nominal voltage, ±5% tolerance, and 500 mW power rating. The impedance increases from 20 Ohms to 22 Ohms, and the maximum operating temperature reduces from 200°C to 175°C. Direct replacement is valid for applications operating below 175°C where the 2 Ohms impedance increase does not affect circuit performance.

Q: What is the difference between BZX79C11-T50A and BZX79C11?

A: Both parts are parametric equivalents with identical electrical specifications: 11 V nominal voltage, ±5% tolerance, 500 mW power, and 20 Ohms impedance. The primary difference is packaging format. BZX79C11-T50A is supplied in cut tape, while BZX79C11 from Taiwan Semiconductor Corporation is supplied in tape & reel. The BZX79C11-T50A maintains the full -65°C to 200°C temperature range, while the Taiwan variant operates to 175°C.

Q: Are the BZX79-C11,113, BZX79-C11,133, and BZX79-C11,143 interchangeable?

A: These three parts are electrically equivalent with identical 11 V voltage, ±5% tolerance, 400 mW power rating, and 20 Ohms impedance. All operate across -65°C to 200°C. The designations reflect different packaging batches or supplier variants from Nexperia and NXP. Selection is based on supplier availability and packaging preference rather than electrical differences.

Q: Can I use a 400 mW part where a 500 mW part is specified?

A: The BZX79-C11 variants rated at 400 mW can replace the 500 mW BZX55C11 only if circuit analysis confirms that the maximum power dissipation does not exceed 400 mW under all operating conditions. The reduced power rating represents a 20% margin reduction and must be evaluated against the specific application's thermal and electrical requirements.

Q: What is the significance of the DO-35 and ALF2 package designations?

A: DO-35 and ALF2 are both through-hole axial package formats for Zener diodes. The BZX55C11, 1N5241B, BZX79C11-T50A, and BZX79C11 use DO-35 packaging. The BZX79-C11 variants (113, 133, 143) use ALF2 packaging. Both package types are mechanically compatible with standard through-hole PCB layouts, though physical dimensions may vary slightly. Verify PCB footprint compatibility before substitution.

Q: Are all substitute parts RoHS compliant?

A: Yes. The BZX79C11-T50A is RoHS3 compliant. The BZX79C11 from Taiwan Semiconductor Corporation is RoHS3 compliant. The BZX79-C11 variants (113, 133, 143) are RoHS3 compliant. The 1N5241B does not specify RoHS status in the provided data. All parts carry REACH unaffected status, indicating no conflict with REACH substance restrictions.

Q: What is the operating temperature consideration when selecting a substitute?

A: The BZX55C11 operates from -65°C to 200°C. The BZX79C11-T50A maintains this full range. The 1N5241B and BZX79C11 (Taiwan variant) operate to 175°C maximum. The BZX79-C11 variants extend to 200°C. For applications requiring operation above 175°C, select BZX79C11-T50A or the BZX79-C11 variants to maintain full temperature coverage.

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