ECS-36-20-28AX-TR 3.6864 MHz Crystal Equivalent & Substitute Parts

Part Overview

The ECS-36-20-28AX-TR is a 3.6864 MHz surface mount crystal oscillator in HC-49/US package with 20pF load capacitance and 200 Ohms ESR. This part is classified as Active product status and is RoHS3 compliant. Substitute parts are necessary when the primary part reaches end-of-life status, inventory constraints occur, or design requirements necessitate alternative electrical or mechanical characteristics within the same frequency and load capacitance specification.

Key Parameters

Parameter	Value
Frequency	3.6864 MHz
Frequency Tolerance	±30ppm
Load Capacitance	20pF
ESR (Equivalent Series Resistance)	200 Ohms
Package / Case	HC-49/US
Operating Temperature Range	-10°C ~ 70°C
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility is determined by the following critical parameters:

Frequency: All substitute parts must operate at 3.6864 MHz
Frequency Tolerance: All parts maintain ±30ppm tolerance
Load Capacitance: All parts specify 20pF load capacitance
Package / Case: All parts use HC-49/US package for mechanical and electrical compatibility
Operating Temperature Range: All parts support -10°C ~ 70°C operating window
Mounting Type: All parts are surface mount compatible

Substitute parts are grouped into two categories based on ESR specification:

200 Ohms ESR Group: ECS-36-20-28A-TR (parametric equivalent, identical electrical characteristics)
150 Ohms ESR Group: ECS-36-20-5P-TR, ECS-36-20-5PX-TR, ECS-36-20-5PVX (lower ESR alternative)

Parameter Comparison

Part Number	Frequency	Frequency Tolerance	Load Capacitance	ESR	Package	Mounting	Temperature Range	Product Status	RoHS Status	Packaging Type
ECS-36-20-28AX-TR	3.6864 MHz	±30ppm	20pF	200 Ω	HC-49/US	Surface Mount	-10°C ~ 70°C	Active	ROHS3 Compliant	Tape & Reel
ECS-36-20-28A-TR	3.6864 MHz	±30ppm	20pF	200 Ω	HC-49/US	Surface Mount	-10°C ~ 70°C	Not For New Designs	RoHS non-compliant	Tape & Reel
ECS-36-20-5P-TR	3.6864 MHz	±30ppm	20pF	150 Ω	HC-49/US	Surface Mount	-10°C ~ 70°C	Not For New Designs	RoHS non-compliant	Tape & Reel
ECS-36-20-5PX-TR	3.6864 MHz	±30ppm	20pF	150 Ω	HC-49/US	Surface Mount	-10°C ~ 70°C	Active	ROHS3 Compliant	Tape & Reel
ECS-36-20-5PVX	3.6864 MHz	±30ppm	20pF	150 Ω	HC-49/US	Surface Mount	-10°C ~ 70°C	Active	ROHS3 Compliant	Cut Tape

Engineering Selection Recommendations

Primary Substitute (Parametric Equivalent): ECS-36-20-28A-TR provides identical electrical and mechanical specifications with 200 Ohms ESR. However, this part carries "Not For New Designs" status and is RoHS non-compliant, limiting its use to legacy system maintenance only.

Recommended Active Substitutes: ECS-36-20-5PX-TR and ECS-36-20-5PVX are both Active status parts with ROHS3 compliance. These parts feature 150 Ohms ESR, which is lower than the primary part. The lower ESR may improve circuit performance in applications sensitive to crystal impedance characteristics. ECS-36-20-5PX-TR is supplied in Tape & Reel packaging, while ECS-36-20-5PVX is supplied in Cut Tape packaging.

Legacy Alternative: ECS-36-20-5P-TR is classified as "Not For New Designs" and is RoHS non-compliant, suitable only for replacement in existing systems where the original part is no longer available.

Frequently Asked Questions (FAQ)

Q: Can ECS-36-20-5PX-TR replace ECS-36-20-28AX-TR directly?

A: Yes, from a functional standpoint. Both parts operate at 3.6864 MHz with ±30ppm tolerance and 20pF load capacitance in HC-49/US package. The primary difference is ESR: ECS-36-20-5PX-TR has 150 Ohms versus 200 Ohms in the original part. This lower ESR typically results in improved frequency stability and reduced power consumption. ECS-36-20-5PX-TR is Active status and ROHS3 compliant, making it the preferred choice for new designs.

Q: What is the difference between ECS-36-20-5PX-TR and ECS-36-20-5PVX?

A: Both parts are electrically identical with 3.6864 MHz frequency, ±30ppm tolerance, 20pF load capacitance, and 150 Ohms ESR. The difference is packaging: ECS-36-20-5PX-TR is supplied in Tape & Reel (TR) format for automated assembly, while ECS-36-20-5PVX is supplied in Cut Tape (CT) format. Additionally, ECS-36-20-5PVX has a lower maximum seated height of 2.60mm compared to 4.30mm for ECS-36-20-5PX-TR, which may be relevant for space-constrained applications.

Q: Why should I avoid ECS-36-20-28A-TR?

A: ECS-36-20-28A-TR is marked "Not For New Designs" and is RoHS non-compliant. While it provides parametric equivalence with 200 Ohms ESR matching the original part, it should only be used for replacement in legacy systems where the original ECS-36-20-28AX-TR is unavailable. For new designs, select ECS-36-20-5PX-TR or ECS-36-20-5PVX.

Q: Are all substitute parts in the same HC-49/US package?

A: Yes, all substitute parts use HC-49/US package, ensuring mechanical compatibility with the original design. However, physical dimensions vary slightly. The original ECS-36-20-28AX-TR measures 0.492" L x 0.191" W with 0.197" maximum seated height. Substitute parts with 150 Ohms ESR measure 0.449" L x 0.189" W, with seated heights ranging from 0.102" to 0.169" depending on the specific part number.

Q: What is the impact of lower ESR on circuit performance?

A: Lower ESR in the 150 Ohms group (ECS-36-20-5PX-TR, ECS-36-20-5PVX, ECS-36-20-5P-TR) compared to 200 Ohms in the original part generally improves frequency stability, reduces phase noise, and decreases power consumption in the oscillator circuit. The frequency tolerance remains ±30ppm across all parts, so accuracy is maintained.

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