BZX55C10 Equivalent & Substitute Parts

Part Overview

The BZX55C10 is a 10 V, 500 mW Zener diode manufactured by onsemi in DO-35 (DO-204AH) axial through-hole packaging. This component is classified as obsolete, though 1700 pieces remain in stock. The BZX55C10 functions as a voltage regulator and protective element in electronic circuits requiring precise voltage reference or transient suppression at 10 V nominal.

Due to the obsolete product status, equivalent and substitute parts are necessary for new designs, long-term availability assurance, and procurement flexibility. Active alternatives with identical or compatible electrical specifications are available from multiple manufacturers.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nom)	10	V
Tolerance	±5%	%
Power - Max	500	mW
Impedance (Max)	15	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 7.5 V	nA
Voltage - Forward (Vf) (Max) @ If	1.3 V @ 100 mA	V
Operating Temperature Range	-65°C to 200°C	°C
Mounting Type	Through Hole	—
Package / Case	DO-35 (DO-204AH)	—

Substitute Part Grouping Explanation

Substitution eligibility for the BZX55C10 is determined by the following critical parameters:

Zener Voltage (Vz): Must be 10 V nominal
Tolerance: Must be ±5%
Power Rating: Must be 500 mW
Package Type: DO-35 (DO-204AH) axial through-hole for direct mechanical compatibility
Operating Temperature Range: Must support -65°C to 200°C or equivalent industrial range
Mounting Type: Through-hole configuration

Substitute parts are grouped into two categories:

Direct Substitutes (Package-Compatible): Parts meeting all electrical specifications and housed in DO-35 packaging, enabling direct board-level replacement without layout modification.

Similar Substitutes (Electrical Equivalents with Package Variation): Parts meeting all electrical specifications but housed in alternative through-hole packages (DO-7), requiring mechanical accommodation but maintaining full functional equivalence.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Tolerance	Power (Max)	Zzt (Max)	Package	Product Status	Temp Range
BZX55C10	onsemi	10 V	±5%	500 mW	15 Ω	DO-35	Obsolete	-65°C to 200°C
1N5240B	Microchip Technology	10 V	±5%	500 mW	17 Ω	DO-35	Active	-65°C to 175°C
BZX79C10-T50A	onsemi	10 V	±5%	500 mW	20 Ω	DO-35	Active	-65°C to 200°C
1N5240BTR	Fairchild Semiconductor	10 V	±5%	500 mW	17 Ω	DO-35	Active	-65°C to 200°C
BZX79C10	Taiwan Semiconductor Corporation	10 V	±5%	500 mW	20 Ω	DO-35	Active	-65°C to 175°C
1N961B	Microchip Technology	10 V	±5%	500 mW	8.5 Ω	DO-7	Active	-65°C to 175°C
1N961B-1	Microchip Technology	10 V	±5%	500 mW	8.5 Ω	DO-35	Active	-65°C to 175°C

Engineering Selection Recommendations

For Direct Board-Level Replacement (DO-35 Package)

The following parts provide direct substitution with identical mechanical fit:

1N5240B (Microchip Technology): Active product status with full electrical compatibility. Operating temperature range of -65°C to 175°C covers standard industrial applications. RoHS non-compliant status should be verified against procurement requirements.
BZX79C10-T50A (onsemi): Active product with ROHS3 compliance. Maintains full -65°C to 200°C operating range matching the original BZX55C10. Available in Cut Tape packaging with 9341 pieces in stock, providing superior long-term availability.
1N5240BTR (Fairchild Semiconductor): Active product with -65°C to 200°C operating range. Highest inventory availability (40764 pieces) ensures procurement security. Compliance certifications should be verified for specific applications.
BZX79C10 (Taiwan Semiconductor Corporation): Active product with ROHS3 compliance. Electrical specifications and operating range (-65°C to 175°C) support standard applications. Available in Tape & Reel packaging.

For Applications Tolerating Package Variation (DO-7 Alternative)

1N961B-1 (Microchip Technology): Active product in DO-35 packaging with identical electrical specifications. Lower impedance (8.5 Ω) provides improved voltage regulation characteristics in some circuit topologies.
1N961B (Microchip Technology): Functionally equivalent but housed in DO-7 package. Requires PCB layout modification but offers lower impedance performance. Not recommended for direct replacement without design review.

Compliance Considerations

BZX79C10-T50A and BZX79C10 variants carry ROHS3 compliance certification, suitable for applications subject to RoHS directives. All listed substitutes maintain REACH Unaffected status and EAR99 export classification consistent with the original part.

Frequently Asked Questions (FAQ)

Q: Can 1N5240B directly replace BZX55C10 on existing PCBs?

A: Yes. Both parts are housed in DO-35 (DO-204AH) axial through-hole packaging with identical pinout and lead spacing. Electrical specifications (10 V, 500 mW, ±5%) are fully compatible. The operating temperature range of 1N5240B (-65°C to 175°C) covers standard industrial applications, though it does not extend to the full 200°C upper limit of the original part.

Q: What is the difference between BZX79C10-T50A and BZX79C10?

A: Both parts are manufactured by onsemi with identical electrical specifications and DO-35 packaging. The primary difference is packaging format: BZX79C10-T50A is supplied in Cut Tape (CT), while BZX79C10 from Taiwan Semiconductor Corporation is supplied in Tape & Reel (TR). Electrical performance is equivalent.

Q: Why does 1N961B-1 have lower impedance (8.5 Ω) than the original BZX55C10 (15 Ω)?

A: Lower impedance indicates improved dynamic response and voltage regulation characteristics. This is a performance advantage in applications requiring fast transient suppression or precise voltage reference stability. The part remains electrically compatible for standard 10 V Zener applications.

Q: Is 1N961B suitable as a substitute despite its DO-7 package?

A: 1N961B is electrically equivalent but requires PCB layout modification due to its DO-7 package geometry. Direct board-level replacement is not possible without rework. Use only when design flexibility permits package accommodation or when superior impedance characteristics (8.5 Ω) provide circuit performance benefits.

Q: Which substitute offers the best long-term availability?

A: 1N5240BTR from Fairchild Semiconductor has the highest inventory (40764 pieces) and active product status, providing maximum procurement security. BZX79C10-T50A from onsemi (9341 pieces) offers strong availability with ROHS3 compliance and extended temperature range support.

Q: Are all substitutes RoHS compliant?

A: No. 1N5240B and 1N961B are RoHS non-compliant. BZX79C10-T50A and BZX79C10 are ROHS3 compliant. Verify compliance requirements for your specific application before selection.

Q: What is the impact of operating temperature range differences?

A: The original BZX55C10 supports -65°C to 200°C. Substitutes 1N5240B, BZX79C10, and 1N961B support -65°C to 175°C. For applications operating above 175°C, use BZX79C10-T50A or 1N5240BTR, which maintain the full 200°C upper limit.

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