BZX85C20 Equivalent & Substitute Parts

Part Overview

The BZX85C20 is a 20 V, 1 W Zener diode manufactured by onsemi in DO-204AL (DO-41) axial through-hole package. This component is classified as obsolete, though 46,032 pieces remain in stock as new original inventory. The BZX85C20 operates across a temperature range of -65°C to 200°C with ±6% voltage tolerance and is suitable for voltage regulation and protection applications in electronic circuits.

Due to its obsolete product status, identifying equivalent and substitute parts is necessary for design continuity, long-term supply chain planning, and new production runs. Substitute parts must maintain electrical compatibility while meeting current manufacturing and compliance standards.

Key Parameters

Parameter	BZX85C20 Specification
Voltage - Zener (Nom)	20 V
Power - Max	1 W
Tolerance	±6%
Impedance (Max)	24 Ohms
Current - Reverse Leakage @ Vr	500 nA @ 14 V
Voltage - Forward (Vf) (Max) @ If	1.2 V @ 200 mA
Operating Temperature	-65°C ~ 200°C
Mounting Type	Through Hole
Package / Case	DO-204AL, DO-41, Axial
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the BZX85C20 is determined by the following critical parameters:

Primary Matching Criteria:

Zener voltage: 20 V nominal
Power dissipation: 1 W maximum (or higher)
Package type: DO-204AL, DO-41, or equivalent axial through-hole configuration
Mounting type: Through hole

Secondary Compatibility Factors:

Voltage tolerance: ±6% or tighter (±5%, ±2%)
Operating temperature range: Must encompass or match -65°C to 200°C
Impedance (Zzt): Maximum 24 Ohms or lower
Forward voltage and reverse leakage characteristics within acceptable limits

Substitute parts are grouped into two categories:

Category A - Direct Equivalents (1 W Power Rating): Parts with 1 W power dissipation, 20 V nominal voltage, and DO-41 or DO-204AL packaging. These provide direct functional replacement with minimal circuit redesign.

Category B - Higher Power Alternatives (≥1 W): Parts with power ratings exceeding 1 W, suitable for applications requiring enhanced thermal margin or higher current handling. These require verification of circuit board thermal management.

Category C - Lower Power Alternatives (500 mW): Parts with 500 mW power rating. These are suitable only for applications where the original 1 W specification includes design margin and actual power dissipation remains below 500 mW.

Parameter Comparison

Part Number	Manufacturer	Vz (Nom)	Power (Max)	Tolerance	Zzt (Max)	Package	Temp Range	Product Status
BZX85C20	onsemi	20 V	1 W	±6%	24 Ohms	DO-41	-65°C ~ 200°C	Obsolete
1N4747A	Lumimax Optoelectronic Technology	20 V	1 W	±5%	22 Ohms	DO-41G	-65°C ~ 200°C	Active
1N5250B	Microchip Technology	20 V	500 mW	±5%	25 Ohms	DO-35	-65°C ~ 175°C	Active
1N5932BRLG	onsemi	20 V	3 W	±5%	14 Ohms	Axial	-65°C ~ 200°C	Active
1EZ20D5-TP	Micro Commercial Co	20 V	500 mW	±5%	22 Ohms	DO-41	-55°C ~ 150°C	Active
1N3027B-1	Microchip Technology	20 V	1 W	±5%	22 Ohms	DO-41	-55°C ~ 175°C	Active
1N4747A TR PBFREE	Central Semiconductor Corp	20 V	1 W	±5%	22 Ohms	DO-41	-65°C ~ 200°C	Active
1N4747CE3/TR13	Microchip Technology	20 V	1 W	±2%	22 Ohms	DO-41	-65°C ~ 150°C	Active
1N4747CP/TR12	Microchip Technology	20 V	1 W	±2%	22 Ohms	DO-41	-65°C ~ 150°C	Active
1N4747CP/TR8	Microchip Technology	20 V	1 W	±2%	22 Ohms	DO-41	-65°C ~ 150°C	Active
1N4747CPE3/TR12	Microchip Technology	20 V	1 W	±2%	22 Ohms	DO-41	-65°C ~ 150°C	Active

Engineering Selection Recommendations

For Direct Replacement (Preferred):

The 1N4747A TR PBFREE (Central Semiconductor Corp) and 1N4747A (Lumimax Optoelectronic Technology) are the primary direct substitutes. Both maintain 1 W power rating, 20 V nominal voltage, DO-41 package configuration, and full -65°C to 200°C operating temperature range. The 1N4747A TR PBFREE carries ROHS3 compliance and is actively manufactured, ensuring long-term availability. The ±5% tolerance is tighter than the original ±6%, providing improved voltage regulation accuracy.

For Enhanced Thermal Performance:

The 1N5932BRLG (onsemi) offers 3 W power dissipation with identical voltage and temperature specifications. This part is suitable for applications requiring additional thermal margin or where circuit board layout permits larger component footprints. The lower impedance (14 Ohms) provides superior dynamic response characteristics.

For Temperature-Constrained Applications:

The 1N4747CE3/TR13 and 1N4747CP/TR12 (Microchip Technology) provide ±2% voltage tolerance with active product status and ROHS3 compliance. However, the maximum operating temperature is limited to 150°C, making these unsuitable for applications requiring the full -65°C to 200°C range of the original BZX85C20.

For Lower Power Budgets:

The 1EZ20D5-TP (Micro Commercial Co) and 1N5250B (Microchip Technology) are rated at 500 mW. These parts are suitable only when circuit analysis confirms actual power dissipation remains below 500 mW with adequate safety margin. The 1EZ20D5-TP operates to 150°C maximum; the 1N5250B to 175°C maximum.

Compliance Considerations:

All substitute parts carry REACH Unaffected status. RoHS compliance varies: 1N4747A TR PBFREE, 1N5932BRLG, 1N4747CE3/TR13, and 1N4747CPE3/TR12 are ROHS3 compliant. The 1N5250B and 1N3027B-1 are RoHS non-compliant. Select based on end-product regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can the 1N5250B (500 mW) replace the BZX85C20 (1 W)?

A: The 1N5250B is suitable only if circuit analysis confirms actual power dissipation remains below 500 mW with adequate design margin. The original 1 W specification must not be assumed as a requirement; verify actual operating conditions. If the circuit is designed for 1 W operation, use a 1 W rated substitute.

Q: What is the difference between DO-41 and DO-35 packages?

A: Both are axial through-hole packages for Zener diodes. DO-41 (DO-204AL) and DO-35 (DO-204AH) differ in physical dimensions and thermal characteristics. The 1N5250B uses DO-35 packaging. Verify PCB footprint compatibility before substitution.

Q: Why do some substitutes have ±2% tolerance while the original has ±6%?

A: Tighter tolerance (±2%) indicates improved manufacturing precision and voltage regulation accuracy. Parts with ±2% tolerance (1N4747CE3/TR13, 1N4747CP/TR12, 1N4747CP/TR8, 1N4747CPE3/TR12) are direct improvements in voltage stability and are electrically compatible with circuits designed for ±6% tolerance.

Q: Is the 1N5932BRLG (3 W) a suitable substitute?

A: Yes, the 1N5932BRLG is electrically compatible and provides enhanced thermal performance. The higher power rating allows greater current handling and thermal margin. Verify that circuit board layout and thermal management accommodate the larger component footprint typical of 3 W Zener diodes.

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

A: The BZX85C20 operates to 200°C maximum. Substitutes with lower maximum temperatures (1EZ20D5-TP at 150°C, 1N4747CE3/TR13 at 150°C, 1N5250B at 175°C) are unsuitable for applications requiring full 200°C operation. Verify actual operating temperature requirements before selection.

Q: Are all substitute parts actively manufactured?

A: All listed substitutes carry Active product status except the original BZX85C20 (Obsolete). Active status ensures continued availability and manufacturing support. For long-term supply chain planning, prioritize parts with Active status and established manufacturer support.

Q: What does ROHS3 compliance mean?

A: ROHS3 compliance indicates conformance to the Restriction of Hazardous Substances Directive 3, restricting lead, cadmium, mercury, and other hazardous materials. Select ROHS3 compliant parts (1N4747A TR PBFREE, 1N5932BRLG, 1N4747CE3/TR13, 1N4747CPE3/TR12) for end products subject to EU or equivalent regulatory requirements.

Q: Can I use 1N4747A variants interchangeably?

A: The 1N4747A base part number is available from multiple manufacturers and in various packaging configurations (tape & reel, cut tape, bulk). All variants with identical electrical specifications (20 V, 1 W, ±5% tolerance) are electrically interchangeable. Verify packaging and reel specifications match procurement requirements.

Q: What is impedance (Zzt) and why does it matter?

A: Impedance (Zzt) is the dynamic impedance of the Zener diode at rated current. Lower impedance indicates better voltage regulation and faster response to load changes. The BZX85C20 specifies 24 Ohms maximum; most substitutes offer 22 Ohms or lower, providing equal or superior performance.

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