SML4749HE3_A/I Zener Diode Equivalent & Substitute Parts

Part Overview

The SML4749HE3_A/I is a 24 V, 1 W surface mount zener diode manufactured by Vishay General Semiconductor - Diodes Division in the DO-214AC (SMA) package. This component is classified as an active product with automotive-grade qualification (AEC-Q101) and is RoHS3 compliant. The part is available in tape and reel packaging with 767 pieces currently in stock.

Substitute parts are identified when equivalent electrical performance and mechanical compatibility are maintained across the specified parameter set. Alternative part numbers within the SML4749 series provide options for different tolerance grades, packaging configurations, or inventory availability while preserving core functional characteristics.

Key Parameters

Parameter	Value	Unit
Voltage - Zener (Nominal)	24	V
Power - Maximum	1	W
Tolerance	±10%	-
Impedance (Maximum)	25	Ohms
Current - Reverse Leakage @ Vr	5	µA @ 18.2 V
Operating Temperature	150	°C
Package / Case	DO-214AC (SMA)	-
Mounting Type	Surface Mount	-
Grade	Automotive	-
Qualification	AEC-Q101	-
RoHS Status	ROHS3 Compliant	-
Moisture Sensitivity Level	1 (Unlimited)	-

Substitute Part Grouping Explanation

Substitution eligibility for zener diodes is determined by matching the following critical parameters:

Primary Matching Criteria:

Zener voltage (Vz): 24 V nominal
Maximum power dissipation: 1 W
Package type: DO-214AC (SMA) surface mount
Impedance (Zzt): 25 Ohms maximum
Reverse leakage current: 5 µA @ 18.2 V
Operating temperature: 150°C maximum

Secondary Considerations:

Tolerance grade (±10% or ±5%)
Automotive qualification status (AEC-Q101)
Compliance certifications (RoHS3, REACH)

All identified substitute parts maintain identical electrical performance specifications and package compatibility with the primary part SML4749HE3_A/I. Variations in tolerance grade and automotive qualification are noted where applicable.

Parameter Comparison

Part Number	Manufacturer	Vz (V)	Power (W)	Tolerance	Zzt (Ohms)	Reverse Leakage (µA @ 18.2V)	Temp (°C)	Package	Grade	AEC-Q101	Inventory (Pcs)
SML4749HE3_A/I	Vishay	24	1	±10%	25	5	150	DO-214AC	Automotive	Yes	767
SML4749-E3/5A	Vishay	24	1	±10%	25	5	150	DO-214AC	-	-	8619
SML4749-E3/61	Vishay	24	1	±10%	25	5	150	DO-214AC	-	-	1900
SML4749A-E3/5A	Vishay	24	1	±5%	25	5	150	DO-214AC	-	-	2754
SML4749AHE3_A/H	Vishay	24	1	±5%	25	5	150	DO-214AC	Automotive	Yes	2509

Engineering Selection Recommendations

SML4749-E3/5A and SML4749-E3/61

These parts are parametric equivalents with ±10% tolerance matching the primary part specification. Both maintain identical electrical characteristics and package compatibility. SML4749-E3/5A offers the highest inventory availability at 8619 pieces. These parts do not carry automotive grade or AEC-Q101 qualification.

SML4749A-E3/5A

This part provides tighter tolerance (±5%) compared to the primary part (±10%) while maintaining all other electrical and mechanical specifications. Automotive grade and AEC-Q101 qualification are not specified for this variant. Inventory availability is 2754 pieces.

SML4749AHE3_A/H

This part is a direct functional equivalent with automotive-grade qualification and AEC-Q101 certification matching the primary part. The tolerance is tighter at ±5%. This variant is suitable for applications requiring automotive-level reliability and compliance. Inventory availability is 2509 pieces.

Selection between substitute parts depends on application requirements for tolerance precision, automotive qualification necessity, and inventory lead time considerations. All substitutes are RoHS3 compliant and maintain MSL 1 (Unlimited) moisture sensitivity rating.

Frequently Asked Questions (FAQ)

Q: Can SML4749-E3/5A be used as a direct replacement for SML4749HE3_A/I?

A: SML4749-E3/5A is a parametric equivalent with identical electrical specifications (24 V, 1 W, ±10% tolerance, DO-214AC package). The primary difference is the absence of automotive grade designation and AEC-Q101 qualification. For non-automotive applications, this part provides full functional equivalence.

Q: What is the difference between ±10% and ±5% tolerance variants?

A: Tolerance refers to the allowable deviation of the zener voltage from the nominal 24 V specification. The ±10% tolerance (SML4749HE3_A/I, SML4749-E3/5A, SML4749-E3/61) permits voltage variation between 21.6 V and 26.4 V. The ±5% tolerance (SML4749A-E3/5A, SML4749AHE3_A/H) restricts variation to 22.8 V and 25.2 V, providing greater precision for voltage regulation applications.

Q: Is AEC-Q101 qualification required for my application?

A: AEC-Q101 qualification indicates the part meets automotive industry reliability standards. This certification is mandatory for automotive applications and recommended for industrial or mission-critical systems. For consumer or general-purpose applications, non-qualified variants (SML4749-E3/5A, SML4749-E3/61, SML4749A-E3/5A) are functionally equivalent.

Q: Are all substitute parts in the same DO-214AC package?

A: Yes. All identified substitute parts use the DO-214AC (SMA) surface mount package with identical mechanical dimensions and land pattern compatibility. No PCB layout modifications are required when substituting between these parts.

Q: What inventory considerations apply to part selection?

A: SML4749-E3/5A has the highest stock level at 8619 pieces, followed by SML4749A-E3/5A at 2754 pieces and SML4749AHE3_A/H at 2509 pieces. The primary part SML4749HE3_A/I has 767 pieces available. Inventory levels influence lead time and procurement strategy.

Q: Can I substitute a ±5% tolerance part for a ±10% tolerance requirement?

A: Yes. A ±5% tolerance part (SML4749A-E3/5A or SML4749AHE3_A/H) exceeds the performance of a ±10% tolerance specification and is fully compatible. The tighter tolerance provides improved voltage regulation accuracy without compromising functionality.

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