Equivalent & Substitute Parts Reference for 1N4477US Zener Diode

Part Overview

The 1N4477US is a Zener diode produced by Microchip Technology, categorized under Diodes, Zener. It features a nominal Zener voltage of 33 V, a maximum power rating of 1.5 W, and a ±5% voltage tolerance. This component is supplied in a surface mount SQ-MELF, A package and maintains an active product status. Given inventory fluctuations, RoHS non-compliance, or changing project requirements, it is necessary to identify and document alternative models with strictly matching electrical and mechanical parameters.

Key Parameters

Parameter	Value
Voltage - Zener (Nom) (Vz)	33 V
Tolerance	±5%
Power - Max	1.5 W
Impedance (Max) (Zzt)	25 Ohms
Current - Reverse Leakage @ Vr	50 nA @ 26.4 V
Voltage - Forward (Vf) (Max) @ If	1.5 V @ 1 A
Operating Temperature	-65°C ~ 175°C (TJ)
Mounting Type	Surface Mount
Package / Case	SQ-MELF, A
Supplier Device Package	D-5A
RoHS Status	RoHS non-compliant
REACH Status	REACH Unaffected
Product Status	Active

Substitute Part Grouping Explanation

Substitution is determined strictly by matching the following key parameters: Voltage - Zener (Nom) (Vz), Tolerance, Power - Max, Impedance (Max) (Zzt), Current - Reverse Leakage @ Vr, Voltage - Forward (Vf) (Max) @ If, Operating Temperature, Mounting Type, Package / Case, and Product Status. Substitutes listed are categorized by equivalency in these parameters.

Parameter Comparison

Parameter	1N4477US	JANTX1N4477US
Manufacturer	Microchip Technology	Microchip Technology
Category	Diodes, Zener	Diodes, Zener
Packaging	Bulk	Bulk
Voltage - Zener (Nom) (Vz)	33 V	33 V
Tolerance	±5%	±5%
Power - Max	1.5 W	1.5 W
Impedance (Max) (Zzt)	25 Ohms	25 Ohms
Current - Reverse Leakage @ Vr	50 nA @ 26.4 V	50 nA @ 26.4 V
Voltage - Forward (Vf) (Max) @ If	1.5 V @ 1 A	1.5 V @ 1 A
Operating Temperature	-65°C ~ 175°C (TJ)	-65°C ~ 175°C (TJ)
Mounting Type	Surface Mount	Surface Mount
Package / Case	SQ-MELF, A	SQ-MELF, A
Supplier Device Package	D-5A	A, SQ-MELF
Product Status	Active	Active
REACH Status	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

Selection between 1N4477US and its parametric equivalent, JANTX1N4477US, can be based strictly on product status and supplied compliance details. Both parts are classified as “Active” and remain unaffected by REACH requirements. The original part 1N4477US is marked as RoHS non-compliant. No additional selection criteria are applicable beyond those explicitly documented.

Frequently Asked Questions (FAQ)

Q1: What parameters must match to substitute a Zener diode in this category?
A1: Substitution requires identical values for Voltage - Zener (Nom) (Vz), Tolerance, Power - Max, Impedance (Max) (Zzt), Current - Reverse Leakage @ Vr, Voltage - Forward (Vf) (Max) @ If, Operating Temperature, Mounting Type, and Package / Case.

Q2: Does package type affect substitution for surface-mount Zener diodes?
A2: Yes. The substitute must have the same package / case (here, SQ-MELF, A) and mounting type to ensure mechanical compatibility.

Q3: Can military-grade equivalents be used as substitutes for commercial grade diodes?
A3: If all specified key electrical and mechanical parameters match, military-grade equivalents such as JANTX1N4477US may be used in place of commercial parts for the same footprint and performance.

Q4: Should RoHS compliance be considered in substitution?
A4: RoHS compliance status must be verified according to project requirements. For 1N4477US, RoHS non-compliance is noted.

Q5: What is the significance of “Active” product status in substitution?
A5: “Active” indicates ongoing availability and manufacturer support, which is essential for reliable sourcing and substitution.

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