LFXTAL078542 Equivalent & Substitute Parts

Part Overview

The LFXTAL078542 is a 4 MHz fundamental mode crystal oscillator manufactured by IQD Frequency Products. This surface mount device is specified for 20pF load capacitance with 130 Ohms equivalent series resistance (ESR) in an HC-49/US package. The part is currently active in production and RoHS3 compliant.

Substitute parts are necessary when the primary part experiences supply constraints, inventory limitations, or when design requirements permit alternative manufacturers with equivalent electrical and mechanical specifications. The substitute parts listed maintain compatibility with the original design through matching frequency, load capacitance, tolerance, operating temperature range, and package form factor.

Substiute Parts

LFXTAL078542

IQD Frequency ProductsIn Stock: 951LFXTAL078542 Datasheet

Current PartRFQ

ECS-40-20-5P-TR

ECS Inc.In Stock: 2762ECS-40-20-5P-TR Datasheet

SimilarRFQ

ECS-40-20-5PVX

ECS Inc.In Stock: 7154ECS-40-20-5PVX Datasheet

SimilarRFQ

ECS-40-20-5PX-TR

ECS Inc.In Stock: 5745ECS-40-20-5PX-TR Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the LFXTAL078542 is determined by the following critical parameters:

Mandatory Matching Parameters:

• Frequency: 4.0000 MHz
• Frequency Tolerance: ±30 ppm
• Load Capacitance: 20 pF
• Operating Mode: Fundamental
• Operating Temperature Range: -10°C to 70°C
• Package / Case: HC-49/US
• Mounting Type: Surface Mount

Allowable Variation Parameters:

• ESR (Equivalent Series Resistance): Substitute parts may have ESR values within the range of 130 to 150 Ohms
• Height - Seated (Max): Substitute parts may have height variations within the HC-49/US package specification range
• Frequency Stability: All substitute parts maintain ±50 ppm stability
• RoHS Compliance Status: Substitute parts may differ in RoHS compliance designation
• Product Status: Substitute parts may have different product lifecycle status (Active, Not For New Designs)

All three substitute parts (ECS-40-20-5P-TR, ECS-40-20-5PVX, ECS-40-20-5PX-TR) meet the mandatory matching parameters and fall within allowable variation ranges.

Parameter Comparison

Engineering Selection Recommendations

Primary Selection: LFXTAL078542

The LFXTAL078542 remains the preferred selection for new designs. This part is actively manufactured, RoHS3 compliant, and features the lowest ESR specification (130 Ohms) among all equivalent options. The part is available in standard Tape & Reel packaging with 858 units in current inventory.

Secondary Selection: ECS-40-20-5PVX

The ECS-40-20-5PVX is the recommended substitute when LFXTAL078542 availability is constrained. This part is actively manufactured, RoHS3 compliant, and maintains all critical electrical parameters. The ECS-40-20-5PVX features a reduced seated height of 2.60 mm, which may provide advantages in space-constrained applications. Inventory availability is high at 7046 units.

Tertiary Selection: ECS-40-20-5PX-TR

The ECS-40-20-5PX-TR is an alternative substitute with active product status and RoHS3 compliance. This part is available in Cut Tape and Digi-Reel packaging options with 5659 units in inventory. The seated height matches the original specification at 4.30 mm.

Not Recommended for New Designs: ECS-40-20-5P-TR

The ECS-40-20-5P-TR carries a "Not For New Designs" product status designation and is RoHS non-compliant. This part should not be selected for new design implementations. Use only when existing designs require continuation with previously qualified components.

Frequently Asked Questions (FAQ)

Q: Can ECS-40-20-5PVX be used as a direct replacement for LFXTAL078542?

A: Yes. The ECS-40-20-5PVX meets all mandatory electrical parameters: 4.0000 MHz frequency, ±30 ppm tolerance, 20 pF load capacitance, and -10°C to 70°C operating range. The part is RoHS3 compliant and actively manufactured. The 20 Ohm ESR increase (150 Ohms vs. 130 Ohms) and 1.70 mm height reduction are within acceptable variation ranges for HC-49/US package specifications.

Q: What is the difference between the three ECS substitute parts?

A: All three ECS parts (ECS-40-20-5P-TR, ECS-40-20-5PVX, ECS-40-20-5PX-TR) share identical electrical specifications. The primary differences are: (1) ECS-40-20-5P-TR has "Not For New Designs" status and is RoHS non-compliant; (2) ECS-40-20-5PVX has a reduced seated height of 2.60 mm; (3) ECS-40-20-5PX-TR is available in Cut Tape and Digi-Reel packaging. For new designs, select either ECS-40-20-5PVX or ECS-40-20-5PX-TR.

Q: Does the 20 Ohm ESR difference between LFXTAL078542 (130 Ohms) and ECS substitutes (150 Ohms) affect circuit performance?

A: ESR variation within the 130 to 150 Ohm range is a permitted parameter variation for HC-49/US package crystals. Both values fall within standard crystal oscillator design tolerances. Circuit design margins established for 130 Ohm ESR accommodate the 150 Ohm specification of substitute parts.

Q: Can ECS-40-20-5P-TR be used in new product designs?

A: No. The ECS-40-20-5P-TR carries explicit "Not For New Designs" product status. This designation indicates the manufacturer does not recommend this part for new design implementations. Select ECS-40-20-5PVX or ECS-40-20-5PX-TR for new designs.

Q: What are the packaging differences between substitute parts?

A: LFXTAL078542 and ECS-40-20-5P-TR and ECS-40-20-5PVX are supplied in Tape & Reel (TR) packaging. ECS-40-20-5PX-TR is available in Cut Tape (CT) and Digi-Reel® packaging options. Tape & Reel packaging is standard for high-volume production; Cut Tape and Digi-Reel are suitable for lower-volume or mixed-component assembly operations.

Q: Is RoHS3 compliance required for my application?

A: RoHS3 compliance is mandatory for products sold in the European Union and many other regulated markets. LFXTAL078542, ECS-40-20-5PVX, and ECS-40-20-5PX-TR are all RoHS3 compliant. ECS-40-20-5P-TR is RoHS non-compliant and should not be used in applications requiring regulatory compliance.

Q: Are all substitute parts available in the same quantities?

A: No. Current inventory levels vary: LFXTAL078542 (858 units), ECS-40-20-5P-TR (2661 units), ECS-40-20-5PVX (7046 units), ECS-40-20-5PX-TR (5659 units). ECS-40-20-5PVX offers the highest inventory availability.