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1N4746A-T Zener Diode 18V 1W Equivalent & Substitute Parts
Part Overview
The 1N4746A-T is a through-hole zener diode rated at 18 V nominal voltage with 1 W maximum power dissipation, manufactured by Diodes Incorporated in DO-41 axial package configuration. This component is classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design support and procurement. The 1N4746A-T maintains ROHS3 compliance and operates across the temperature range of -65°C to 175°C. Substitute parts must maintain electrical equivalence across voltage regulation, power handling, and thermal characteristics to ensure direct circuit compatibility.
Substiute Parts
Key Parameters
| Parameter | Value | Unit |
|---|---|---|
| Voltage - Zener (Nominal) | 18 | V |
| Tolerance | ±5 | % |
| Power - Maximum | 1 | W |
| Impedance (Maximum) | 20 | Ohms |
| Current - Reverse Leakage @ Vr | 5 | µA @ 13.7 V |
| Voltage - Forward (Maximum) @ If | 1.2 | V @ 200 mA |
| Operating Temperature Range | -65 to 175 | °C |
| Mounting Type | Through Hole | |
| Package / Case | DO-204AL, DO-41, Axial |
Substitute Part Grouping Explanation
Substitution of the 1N4746A-T is determined by strict equivalence across the following electrical and mechanical parameters:
Critical Substitution Parameters:
- Voltage - Zener (Nominal): 18 V
- Tolerance: ±5%
- Power - Maximum: 1 W
- Impedance (Maximum): 20 Ohms
- Current - Reverse Leakage @ Vr: 5 µA @ 13.7 V
- Voltage - Forward (Maximum) @ If: 1.2 V @ 200 mA
- Mounting Type: Through Hole
- Package / Case: DO-204AL, DO-41, Axial
All substitute parts listed maintain these electrical specifications. Operating temperature range variations are noted but do not preclude substitution where the application operates within the substitute part's specified range. Packaging format (Cut Tape, Tape & Reel, or Bulk) represents a procurement distinction rather than an electrical parameter and does not affect circuit compatibility.
Parameter Comparison
| Part Number | Manufacturer | Vz (V) | Tolerance (%) | Power (W) | Zzt (Ohms) | Vf @ If (V @ mA) | Temp Range (°C) | Product Status | RoHS Status |
|---|---|---|---|---|---|---|---|---|---|
| 1N4746A-T | Diodes Incorporated | 18 | ±5 | 1 | 20 | 1.2 @ 200 | -65 to 175 | Obsolete | ROHS3 Compliant |
| 1N4746A,113 | Nexperia USA Inc. | 18 | ±5 | 1 | 20 | 1.2 @ 200 | -65 to 200 | Active | ROHS3 Compliant |
| 1N4746AP/TR8 | Microchip Technology | 18 | ±5 | 1 | 20 | 1.2 @ 200 | -65 to 150 | Active | RoHS non-compliant |
| 1N4746ATR | onsemi | 18 | ±5 | 1 | 20 | Not specified | -65 to 200 | Active | ROHS3 Compliant |
| 1N4746A,133 | NXP USA Inc. | 18 | ±5 | 1 | 20 | 1.2 @ 200 | -65 to 200 | Active | Not specified |
| 1N4746A-T50A | onsemi | 18 | ±5 | 1 | 20 | Not specified | -65 to 200 | Active | ROHS3 Compliant |
| 1N4746A | Microchip Technology | 18 | ±5 | 1 | 20 | Not specified | -65 to 200 | Active | RoHS non-compliant |
| 1N4746A G | Microsemi Corporation | 18 | ±5 | 1 | 20 | 1.2 @ 200 | -65 to 175 | Active | RoHS non-compliant |
| 1N4746AGE3 | Microchip Technology | 18 | ±5 | 1 | 20 | 1.2 @ 200 | -65 to 175 | Active | ROHS3 Compliant |
| 1N4746AP/TR12 | Microchip Technology | 18 | ±5 | 1 | 20 | 1.2 @ 200 | -65 to 150 | Active | RoHS non-compliant |
Engineering Selection Recommendations
Primary Substitutes (Active Status, ROHS3 Compliant):
1N4746A,113 (Nexperia USA Inc.) and 1N4746ATR (onsemi) are the preferred direct substitutes. Both parts maintain full electrical equivalence to the 1N4746A-T across all critical parameters. 1N4746A,113 extends the operating temperature range to 200°C, providing enhanced thermal margin. 1N4746ATR offers equivalent performance with active product status and ROHS3 compliance. Both are available in high inventory quantities (125,300 and 27,300 units respectively).
Secondary Substitutes (Active Status, Extended Temperature Range):
1N4746A-T50A (onsemi) and 1N4746A,133 (NXP USA Inc.) provide active alternatives with extended operating temperature to 200°C. 1N4746A-T50A maintains ROHS3 compliance with 9,382 units in stock. 1N4746A,133 offers bulk packaging with 128,299 units available.
Alternative Substitutes (Active Status, Temperature-Dependent Selection):
1N4746AGE3 (Microchip Technology) maintains the original -65°C to 175°C temperature range with ROHS3 compliance and 1,116 units in stock. 1N4746A G (Microsemi Corporation) provides equivalent electrical performance with 993 units available, though RoHS non-compliant status requires compliance verification for new designs.
Packaging Considerations:
1N4746AP/TR8 and 1N4746AP/TR12 (Microchip Technology) are tape and reel packaged variants suitable for automated assembly. Both are RoHS non-compliant and operate to 150°C maximum, representing a reduced thermal margin compared to the original specification.
Compliance Status:
For applications requiring ROHS3 compliance, select from: 1N4746A,113, 1N4746ATR, 1N4746A-T50A, or 1N4746AGE3. For applications without RoHS requirements, all listed substitutes are electrically equivalent.
Frequently Asked Questions (FAQ)
Q: Can 1N4746A,113 directly replace 1N4746A-T in existing circuits?
A: Yes. 1N4746A,113 maintains identical electrical specifications across voltage regulation (18 V ±5%), power dissipation (1 W), impedance (20 Ohms maximum), and forward voltage characteristics. The extended operating temperature range (-65°C to 200°C versus -65°C to 175°C) provides additional thermal margin without affecting circuit operation.
Q: What is the difference between Cut Tape (CT) and Tape & Reel (TR) packaging?
A: Cut Tape and Tape & Reel represent procurement and handling formats only. Electrically and mechanically, the diodes are identical. Cut Tape is suitable for manual assembly and small-quantity applications. Tape & Reel packaging is optimized for automated pick-and-place assembly in high-volume production. Both formats use the same DO-41 axial package.
Q: Are all substitute parts compatible with the original DO-41 package footprint?
A: Yes. All listed substitutes use DO-204AL, DO-41, or Axial package designations, which are mechanically and electrically equivalent. The axial lead configuration and component body dimensions remain consistent across all substitutes, enabling direct board-level replacement without layout modification.
Q: Why do some substitutes specify different maximum operating temperatures?
A: Operating temperature range reflects the manufacturer's thermal characterization and qualification limits. The 1N4746A-T operates to 175°C maximum. Substitutes rated to 200°C (1N4746A,113, 1N4746ATR, 1N4746A-T50A, 1N4746A,133) provide extended thermal capability. Substitutes rated to 150°C (1N4746AP/TR8, 1N4746AP/TR12) represent a reduced thermal margin. Selection depends on the application's actual operating temperature requirements.
Q: Is RoHS compliance a critical factor for substitute selection?
A: RoHS compliance status depends on application requirements and regulatory jurisdiction. ROHS3-compliant substitutes include 1N4746A,113, 1N4746ATR, 1N4746A-T50A, and 1N4746AGE3. RoHS non-compliant alternatives (1N4746AP/TR8, 1N4746AP/TR12, 1N4746A, 1N4746A G) are electrically equivalent but require compliance verification for new product designs or regulated markets.
Q: What is the significance of the impedance (Zzt) parameter in zener diode selection?
A: Impedance (Zzt) of 20 Ohms maximum defines the dynamic resistance of the zener diode in the reverse-biased regulation region. All listed substitutes maintain this specification, ensuring equivalent voltage regulation performance and transient response characteristics in circuit applications.
Q: Can 1N4746A (base part number without suffix) be used as a substitute?
A: Yes. The base part number 1N4746A from Microchip Technology maintains full electrical equivalence. However, this variant is RoHS non-compliant and operates to 200°C maximum. Verify compliance requirements before selection. The part is available in 50,200 units.
Q: How does forward voltage (Vf) affect circuit performance?
A: Forward voltage of 1.2 V @ 200 mA is specified for several substitutes and matches the original 1N4746A-T specification. This parameter defines the voltage drop across the diode during forward conduction and affects circuit biasing and power dissipation calculations. Substitutes without specified Vf values maintain equivalent forward characteristics based on identical base part number and electrical classification.
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