1N5991B-TP Zener Diode Equivalent & Substitute Parts

Part Overview

The 1N5991B-TP is a 4.3 V, 500 mW Zener diode manufactured by Micro Commercial Co in DO-35 through-hole package. This component is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and production continuity. Equivalent parts maintain identical electrical and mechanical specifications, while substitute parts provide functional alternatives within acceptable parameter tolerances for 4.3 V Zener diode applications.

Substiute Parts

1N5991B-TP

Micro Commercial CoIn Stock: 10191N5991B-TP Datasheet

Current PartRFQ

1N5991B TR PBFREE

Central Semiconductor CorpIn Stock: 7051N5991B TR PBFREE Datasheet

DirectRFQ

1N5229B TR PBFREE

Central Semiconductor CorpIn Stock: 7961N5229B TR PBFREE Datasheet

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1N5229B-T

Diodes IncorporatedIn Stock: 22051N5229B-T Datasheet

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1N5991B

Microchip TechnologyIn Stock: 10481N5991B Datasheet

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1N5991D

Microchip TechnologyIn Stock: 11161N5991D Datasheet

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TZX4V3D-TAP

Vishay General Semiconductor - Diodes DivisionIn Stock: 30733TZX4V3D-TAP Datasheet

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TZX4V3D-TR

Vishay General Semiconductor - Diodes DivisionIn Stock: 847TZX4V3D-TR Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 1N5991B-TP is determined by the following critical parameters:

Primary Substitution Criteria:

• Zener voltage: 4.3 V nominal
• Power dissipation: 500 mW maximum
• Package type: DO-35 through-hole axial configuration
• Operating temperature range compatibility
• Reverse leakage current: 5 µA @ 1 V

Secondary Compatibility Factors:

• Impedance (Zzt): Maximum 88 Ohms to 100 Ohms acceptable
• Forward voltage: 1.1 V to 1.5 V @ specified current
• Tolerance: ±1% to ±5% acceptable
• RoHS and REACH compliance status

Parts are grouped into two categories: Direct Equivalents (identical specifications from different manufacturers) and Functional Substitutes (minor parameter variations within acceptable engineering tolerances).

Parameter Comparison

Engineering Selection Recommendations

Direct Equivalents (Identical Specifications):

The 1N5991B TR PBFREE from Central Semiconductor Corp is the primary direct equivalent. It maintains all critical electrical parameters of the original 1N5991B-TP, including 4.3 V nominal Zener voltage, ±5% tolerance, 500 mW power rating, and 88 Ohms maximum impedance. This part is active and ROHS3 compliant, providing immediate replacement capability with tape and reel packaging for automated assembly.

The 1N5991B from Microchip Technology is functionally equivalent with identical impedance (88 Ohms) and electrical characteristics. However, the maximum operating temperature is reduced to 175°C compared to the original 200°C specification. This part is available in bulk packaging and is active, though RoHS non-compliant.

The 1N5991D from Microchip Technology offers improved tolerance (±1% versus ±5%), maintaining the same 88 Ohms impedance and 500 mW power rating. Operating temperature is 175°C maximum. This part is suitable for applications requiring tighter voltage tolerance specifications.

Functional Substitutes (Parameter Variations):

The 1N5229B TR PBFREE and 1N5229B-T are functional substitutes with identical Zener voltage and power rating but reduced impedance (22 Ohms versus 88 Ohms) and improved forward voltage characteristics (1.1 V @ 200 mA versus 1.5 V @ 100 mA). These parts are active and ROHS3 compliant. The lower impedance provides superior voltage regulation performance in applications where dynamic impedance is critical.

The TZX4V3D-TAP and TZX4V3D-TR from Vishay are automotive-grade substitutes (AEC-Q101 qualified) with 4.3 V Zener voltage and 500 mW power rating. Impedance is slightly higher at 100 Ohms maximum, and operating temperature is limited to 175°C. These parts are ROHS3 compliant and suitable for automotive and high-reliability applications.

Compliance Considerations:

For applications requiring ROHS3 compliance, select from: 1N5991B TR PBFREE, 1N5229B TR PBFREE, 1N5229B-T, TZX4V3D-TAP, or TZX4V3D-TR. The Microchip 1N5991B and 1N5991D are RoHS non-compliant and should be used only in applications where RoHS exemptions apply.

For applications requiring automotive qualification, TZX4V3D-TAP and TZX4V3D-TR are AEC-Q101 qualified and recommended.

Frequently Asked Questions (FAQ)

Q: Can I use 1N5229B parts as a direct replacement for 1N5991B-TP?

A: The 1N5229B series is a functional substitute, not a direct equivalent. While both maintain 4.3 V Zener voltage and 500 mW power rating, the 1N5229B has significantly lower impedance (22 Ohms versus 88 Ohms) and different forward voltage characteristics. This substitution is acceptable in applications where lower dynamic impedance improves performance, but circuit validation is required for designs dependent on the original 88 Ohms impedance specification.

Q: What is the difference between 1N5991B and 1N5991D?

A: Both parts are manufactured by Microchip Technology with identical electrical characteristics except for tolerance. The 1N5991B has ±5% tolerance, while the 1N5991D has ±1% tolerance. The 1N5991D is suitable for applications requiring tighter Zener voltage control. Both have maximum operating temperature of 175°C and 88 Ohms impedance.

Q: Are TZX4V3D parts suitable for non-automotive applications?

A: Yes. TZX4V3D-TAP and TZX4V3D-TR are automotive-qualified (AEC-Q101) but are fully functional in non-automotive applications. The automotive qualification indicates higher reliability and quality standards, making these parts suitable for any application requiring robust performance. The primary consideration is the 175°C maximum operating temperature versus the original 200°C specification.

Q: What packaging options are available?

A: Substitute parts are available in multiple packaging formats: Tape & Reel (TR) for automated assembly, Cut Tape (CT) for semi-automated or manual assembly, and Bulk for manual insertion. The 1N5991B TR PBFREE, 1N5229B TR PBFREE, and TZX4V3D-TR are tape and reel packaged. The 1N5229B-T, 1N5991B, and 1N5991D are bulk packaged. The TZX4V3D-TAP is cut tape packaged.

Q: Which substitute part has the lowest impedance?

A: The 1N5229B series (both TR PBFREE and -T variants) has the lowest impedance at 22 Ohms maximum, compared to 88 Ohms for the original 1N5991B-TP. Lower impedance provides better voltage regulation and faster transient response in applications with varying load conditions.

Q: Is the operating temperature range important for my application?

A: The original 1N5991B-TP operates from -65°C to 200°C. Most active substitutes (1N5991B, 1N5991D, TZX4V3D-TAP, TZX4V3D-TR) are limited to 175°C maximum. If your application requires operation above 175°C, the 1N5991B TR PBFREE from Central Semiconductor Corp maintains the full -65°C to 200°C range. Verify your circuit's maximum operating temperature requirement before selection.

Q: What does ROHS3 compliance mean?

A: ROHS3 compliance indicates the part meets the Restriction of Hazardous Substances Directive, restricting lead, cadmium, mercury, and other hazardous materials. For new designs and applications subject to environmental regulations, select ROHS3-compliant parts: 1N5991B TR PBFREE, 1N5229B TR PBFREE, 1N5229B-T, TZX4V3D-TAP, or TZX4V3D-TR.

Q: Can I mix different substitute parts in the same circuit board?

A: All listed substitute parts are functionally compatible for 4.3 V Zener diode applications. However, mixing parts with different impedance values (88 Ohms versus 22 Ohms versus 100 Ohms) in parallel or series configurations may produce uneven current distribution. For consistency and predictable circuit behavior, use a single part number across the entire assembly.