1N756ATR Zener Diode Equivalent & Substitute Parts

Part Overview

The 1N756ATR is an 8.2 V, 500 mW Zener diode manufactured by onsemi in DO-35 axial through-hole packaging. This component is classified as obsolete, with 707 units currently in stock. The diode operates across a temperature range of -65°C to 200°C and maintains ±5% voltage tolerance. Due to its obsolete status, identifying equivalent and substitute parts is essential for design continuity, long-term supply chain planning, and system reliability in applications requiring 8.2 V voltage regulation or protection circuits.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	8.2	V
Tolerance	±5%	-
Power - Maximum	500	mW
Impedance (Maximum)	8	Ohms
Current - Reverse Leakage @ Vr	100 nA @ 1 V	-
Voltage - Forward (Maximum) @ If	1.5 V @ 200 mA	-
Operating Temperature Range	-65 to 200	°C
Mounting Type	Through Hole	-
Package / Case	DO-204AH, DO-35, Axial	-
Product Status	Obsolete	-

Substitute Part Grouping Explanation

Substitution of the 1N756ATR is determined by strict alignment of electrical and mechanical parameters. The critical parameters governing substitutability are:

Electrical Parameters:

Zener voltage (Vz): Must be 8.2 V nominal
Voltage tolerance: ±5% or tighter
Power dissipation: Minimum 500 mW (higher ratings acceptable for higher-power applications)
Impedance: Maximum 8 Ohms or lower (lower impedance preferred for improved regulation)
Reverse leakage current: Lower values indicate better performance
Forward voltage: Compatibility at 200 mA forward current
Operating temperature: Minimum -65°C to 200°C range (or compatible subset)

Mechanical Parameters:

Mounting type: Through hole only
Package options: DO-35 (DO-204AH) primary; DO-7 (DO-204AA) and DO-41 (DO-204AL) acceptable for form-factor flexibility
Lead configuration: Axial leads

Substitute parts are categorized as follows:

Direct Equivalents (Same electrical and package specifications): 1N5237B, BZX79C8V2, 1N5237BTR, 1N756A-1

Parametric Equivalents (Same electrical specifications, different package): 1N756A (DO-7 package)

Higher Power Alternatives (Same voltage/tolerance, increased power rating): 1N4738A (1 W, DO-41), 1N5065 (3 W, Axial), 1N5923BP-TP (1.5 W, DO-41)

Base Part Reference: 1N756 (±10% tolerance variant)

Incomplete Data: 1N959B (insufficient parameter specification for full comparison)

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Tolerance	Power (mW)	Zzt (Ohms)	Package	Temp Range (°C)	Status
1N756ATR	onsemi	8.2	±5%	500	8	DO-35	-65 to 200	Obsolete
1N5237B	Microchip Technology	8.2	±5%	500	8	DO-35	-65 to 175	Active
BZX79C8V2	Taiwan Semiconductor Corporation	8.2	±5%	500	15	DO-35	-65 to 175	Active
1N5237BTR	Fairchild Semiconductor	8.2	±5%	500	8	DO-35	-65 to 200	Active
1N756A-1	Microchip Technology	8.2	±5%	500	8	DO-35	-65 to 175	Active
1N756A	Microchip Technology	8.2	±5%	500	8	DO-7	-65 to 175	Active
1N4738A	Lumimax Optoelectronic Technology	8.2	±5%	1000	4.5	DO-41	-65 to 200	Active
1N5065	Microchip Technology	8.2	±5%	3000	3	Axial	-65 to 175	Active
1N5923BP-TP	Micro Commercial Co	8.2	±5%	1500	3.5	DO-41	-55 to 175	Active
1N756	Microchip Technology	8.2	±10%	500	8	DO-35	-65 to 175	Active

Engineering Selection Recommendations

For Direct Replacement (Same Package, Same Electrical Specifications):

1N5237BTR (Fairchild Semiconductor) is the primary recommended substitute. It maintains identical electrical parameters (8.2 V, ±5%, 500 mW, 8 Ohms impedance) and extends the operating temperature range to -65°C to 200°C, matching the original 1N756ATR specification. Product status is active with 59,930 units in stock. This part provides the highest compatibility for direct PCB substitution without design modification.

1N5237B (Microchip Technology) is a secondary direct equivalent with 36,365 units available. It matches all electrical parameters but operates to 175°C maximum, which is acceptable for most applications not requiring the full 200°C upper limit. This part is RoHS non-compliant.

1N756A-1 (Microchip Technology) is functionally equivalent with 614 units in stock. It maintains all electrical specifications and the DO-35 package. Operating temperature is -65°C to 175°C.

For Package-Flexible Applications (Same Electrical Specifications, Different Package):

1N756A (Microchip Technology) provides identical electrical performance in DO-7 (DO-204AA) axial package with 17,159 units available. This substitution requires PCB layout modification to accommodate the different package form factor.

For Higher Power Dissipation Requirements:

1N4738A (Lumimax Optoelectronic Technology) offers 1 W power rating in DO-41 package with improved impedance (4.5 Ohms). Suitable for applications requiring greater thermal headroom. 10,110 units in stock. RoHS compliant.

1N5923BP-TP (Micro Commercial Co) provides 1.5 W rating in DO-41 package with 3.5 Ohms impedance. 908 units available. RoHS3 compliant. Operating temperature minimum is -55°C (not -65°C).

1N5065 (Microchip Technology) delivers 3 W power dissipation for high-current regulation applications. 939 units in stock. Axial package configuration.

Compliance Considerations:

The original 1N756ATR has REACH Unaffected status. Substitute parts maintain this classification. RoHS compliance varies: 1N4738A and 1N5923BP-TP are RoHS3 compliant; BZX79C8V2 is ROHS3 compliant; 1N5237B, 1N756A, and 1N5237BTR are RoHS non-compliant. Select based on end-product regulatory requirements.

Not Recommended:

1N756 (±10% tolerance) introduces tighter voltage tolerance than the original ±5% specification and is not suitable for precision voltage regulation applications.

1N959B lacks sufficient parameter documentation for reliable substitution assessment.

Frequently Asked Questions (FAQ)

Q: Can I use 1N5237B as a direct replacement for 1N756ATR?

A: Yes, 1N5237B is electrically equivalent with identical 8.2 V, ±5%, 500 mW specifications and DO-35 package. The operating temperature range is -65°C to 175°C versus the original 200°C maximum. This is acceptable unless your application requires operation above 175°C. 1N5237B is currently in active production with high inventory availability.

Q: What is the difference between 1N5237BTR and 1N5237B?

A: Both parts are manufactured by different suppliers (Fairchild vs. Microchip) with identical electrical specifications. 1N5237BTR extends the operating temperature to 200°C, matching the original 1N756ATR specification. 1N5237BTR is the preferred choice for temperature-critical applications.

Q: Can I substitute a higher power Zener diode like 1N4738A (1 W) for the 500 mW 1N756ATR?

A: Yes, higher power ratings are acceptable substitutes. The 1N4738A maintains the 8.2 V nominal voltage and ±5% tolerance. The increased power dissipation (1 W vs. 500 mW) and lower impedance (4.5 Ohms vs. 8 Ohms) provide improved regulation characteristics. However, the package changes from DO-35 to DO-41, requiring PCB layout modification. This substitution is suitable for applications where thermal margin is beneficial.

Q: Does package type affect electrical performance?

A: Package type (DO-35, DO-7, DO-41) does not alter the core electrical specifications (Zener voltage, tolerance, power rating). Package selection is determined by PCB layout constraints, thermal management requirements, and mechanical space availability. All axial through-hole packages listed are electrically interchangeable if the electrical parameters match.

Q: What does impedance (Zzt) mean, and why does it vary between equivalent parts?

A: Impedance (Zzt) is the dynamic impedance of the Zener diode at the specified test current. Lower impedance indicates better voltage regulation stability and reduced output voltage ripple. The 1N756ATR specifies 8 Ohms maximum. Substitutes with lower impedance (such as 1N4738A at 4.5 Ohms or 1N5065 at 3 Ohms) provide superior regulation performance. Higher impedance (BZX79C8V2 at 15 Ohms) is acceptable but offers less stable regulation.

Q: Is RoHS compliance required for my application?

A: RoHS compliance depends on your end-product market and regulatory jurisdiction. If RoHS compliance is mandatory, select 1N4738A (RoHS compliant) or 1N5923BP-TP (RoHS3 compliant). If RoHS compliance is not required, all listed substitutes are acceptable. Verify your specific regulatory requirements before final part selection.

Q: Can I use 1N756 (±10% tolerance) instead of 1N756ATR (±5% tolerance)?

A: 1N756 is not recommended as a substitute. The ±10% tolerance is significantly looser than the original ±5% specification. This introduces unacceptable voltage variation in precision voltage regulation circuits. Use only if your application tolerates ±10% voltage deviation.

Q: What is the difference between reverse leakage current specifications across substitute parts?

A: Reverse leakage current indicates the small current flowing through the Zener diode when reverse-biased below the Zener voltage. Lower leakage current (1N756ATR at 100 nA @ 1 V, 1N756A-1 at 100 nA @ 1 V) indicates better performance in low-current applications. Higher leakage (BZX79C8V2 at 700 nA @ 5 V) is acceptable for most applications but may affect precision circuits. Leakage current is not a primary substitution criterion unless your circuit operates in extremely low-current regimes.

Q: Why is the 1N756ATR obsolete, and how long will substitutes remain available?

A: The 1N756ATR is classified as obsolete by onsemi, indicating end-of-life status. Recommended substitutes (1N5237BTR, 1N5237B, 1N756A-1) are in active production status with substantial inventory levels (36,365 to 59,930 units), ensuring long-term availability. Active-status parts typically remain available for 5-10 years minimum from major manufacturers.

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