1N970B Zener Diode Equivalent & Substitute Parts

Part Overview

The 1N970B is a 24 V, 500 mW Zener diode manufactured by onsemi in a DO-35 axial through-hole package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The 1N970B operates across a temperature range of -65°C to 200°C with ±5% voltage tolerance and serves applications requiring precision voltage regulation and transient protection in electronic circuits.

Key Parameters

Parameter	Value
Voltage - Zener (Nom)	24 V
Power - Max	500 mW
Tolerance	±5%
Impedance (Max)	33 Ohms
Current - Reverse Leakage @ Vr	5 µA @ 18.2 V
Operating Temperature	-65°C ~ 200°C
Mounting Type	Through Hole
Package / Case	DO-35 (DO-204AH)

Substitute Part Grouping Explanation

Substitution of the 1N970B is determined by matching the following critical parameters: nominal Zener voltage (24 V), voltage tolerance (±5%), power dissipation capability, impedance characteristics, reverse leakage current specifications, and operating temperature range. Package compatibility and mounting type are secondary considerations that may require circuit board layout adjustments.

The substitute parts are grouped into two categories:

Parametric Equivalents maintain identical electrical specifications and package form factors, enabling direct replacement without circuit modification.

Functional Equivalents provide the same 24 V Zener voltage and ±5% tolerance but differ in power rating, package type, or impedance, requiring evaluation for specific application requirements.

Parameter Comparison

Parameter	1N970B (Main)	1N5252B	1N970A	1N4749A	1N5934BP-TP
Manufacturer	onsemi	Microchip Technology	Microchip Technology	Lumimax Optoelectronic Technology	Micro Commercial Co
Product Status	Obsolete	Active	Active	Active	Active
Voltage - Zener (Nom)	24 V	24 V	24 V	24 V	24 V
Tolerance	±5%	±5%	±10%	±5%	±5%
Power - Max	500 mW	500 mW	500 mW	1 W	1.5 W
Impedance (Max)	33 Ohms	33 Ohms	33 Ohms	25 Ohms	19 Ohms
Current - Reverse Leakage @ Vr	5 µA @ 18.2 V	100 nA @ 18 V	5 µA @ 18.2 V	5 µA @ 18.2 V	1 µA @ 18.2 V
Operating Temperature	-65°C ~ 200°C	-65°C ~ 175°C	-65°C ~ 175°C	-65°C ~ 200°C	-55°C ~ 175°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	DO-35 (DO-204AH)	DO-35 (DO-204AH)	DO-7 (DO-204AA)	DO-41 (DO-204AL)	DO-41 (DO-204AL)
RoHS Status	Not specified	RoHS non-compliant	RoHS non-compliant	RoHS Compliant	ROHS3 Compliant

Engineering Selection Recommendations

1N5252B (Microchip Technology) is the primary parametric equivalent for direct replacement. It maintains identical electrical specifications (24 V, 500 mW, ±5%, 33 Ohms impedance) and package form (DO-35). The 1N5252B is active in production and REACH compliant. The operating temperature range is reduced to -65°C to 175°C compared to the 1N970B's -65°C to 200°C maximum. Reverse leakage current is significantly lower at 100 nA versus 5 µA, representing improved performance. RoHS non-compliance status matches the original part.

1N970A (Microchip Technology) provides parametric equivalence in voltage (24 V), power (500 mW), and impedance (33 Ohms) with active product status. The tolerance is widened to ±10% and the package changes to DO-7, requiring circuit board layout modification. Operating temperature range is -65°C to 175°C. This option is suitable when package footprint changes are acceptable.

1N4749A (Lumimax Optoelectronic Technology) maintains 24 V nominal voltage and ±5% tolerance with increased power rating (1 W) and improved impedance (25 Ohms). The DO-41 package requires board layout adjustment. Operating temperature extends to 200°C, matching the original part's upper limit. RoHS compliance status is active. This option provides enhanced thermal performance for applications with higher power dissipation requirements.

1N5934BP-TP (Micro Commercial Co) offers the highest power rating (1.5 W) and lowest impedance (19 Ohms) among substitutes, with 24 V nominal voltage and ±5% tolerance. The DO-41 package requires board layout modification. Operating temperature range is -55°C to 175°C, with a reduced lower limit. ROHS3 compliance and tape & reel packaging indicate modern manufacturing standards. This option is selected for applications requiring maximum thermal headroom and lowest dynamic impedance.

Frequently Asked Questions (FAQ)

Q: Can the 1N5252B directly replace the 1N970B without circuit modification?

A: Yes. The 1N5252B is a parametric equivalent with identical voltage (24 V), power (500 mW), tolerance (±5%), impedance (33 Ohms), and package (DO-35). Direct PCB substitution is possible. The reduced operating temperature maximum (175°C versus 200°C) and improved reverse leakage (100 nA versus 5 µA) do not prevent substitution in standard applications.

Q: What is the primary difference between the 1N970A and 1N970B?

A: The 1N970A uses a DO-7 package instead of DO-35, requiring circuit board layout changes. The voltage tolerance is also widened to ±10% compared to ±5%. Electrical performance in voltage regulation and impedance remains equivalent at 24 V and 33 Ohms.

Q: When should I select the 1N4749A or 1N5934BP-TP over the 1N5252B?

A: Select 1N4749A (1 W) or 1N5934BP-TP (1.5 W) when circuit analysis indicates power dissipation exceeding 500 mW. The 1N4749A provides moderate power increase with improved impedance (25 Ohms). The 1N5934BP-TP offers maximum power capacity (1.5 W) and lowest impedance (19 Ohms) for demanding applications. Both require DO-41 package accommodation.

Q: Are there compliance differences between substitute options?

A: The 1N4749A is RoHS Compliant. The 1N5934BP-TP is ROHS3 Compliant. The 1N5252B and 1N970A are RoHS non-compliant. All parts are REACH Unaffected. Select based on end-product compliance requirements.

Q: How does reverse leakage current affect substitution?

A: The 1N5252B exhibits significantly lower reverse leakage (100 nA) compared to the 1N970B (5 µA). Lower leakage improves circuit performance in precision applications. The 1N5934BP-TP (1 µA) provides intermediate leakage characteristics. Higher leakage in the original 1N970B does not prevent substitution with lower-leakage alternatives.

Q: What package considerations apply to these substitutes?

A: The 1N5252B maintains the DO-35 axial package, requiring no board layout changes. The 1N970A uses DO-7, and the 1N4749A and 1N5934BP-TP use DO-41, both requiring different PCB hole spacing and lead positioning. Verify mechanical compatibility before selection.

Q: Can I use a higher-power substitute in a circuit designed for 500 mW?

A: Yes. Higher power-rated devices (1 W or 1.5 W) operate safely in 500 mW applications. The circuit will not exceed the device's power dissipation limit. Verify that impedance changes (lower impedance in higher-power devices) do not affect voltage regulation performance in your specific circuit topology.

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