FC4UTCBAF4.0-BAG100 Equivalent & Substitute Parts

Part Overview

The FC4UTCBAF4.0-BAG100 is a 4 MHz through-hole crystal oscillator manufactured by Fox Electronics in the HC-49/U package. This component operates at a fundamental frequency with ±30ppm tolerance and 100 Ohms equivalent series resistance (ESR). The part is currently classified as obsolete, making identification of equivalent and substitute parts essential for ongoing system support and component procurement.

Key Parameters

Parameter	Value
Frequency	4 MHz
Frequency Tolerance	±30ppm
Frequency Stability	±50ppm
ESR (Equivalent Series Resistance)	100 Ohms
Operating Mode	Fundamental
Operating Temperature Range	-20°C ~ 70°C
Mounting Type	Through Hole
Package / Case	HC-49/U
Load Capacitance	Series

Substitute Part Grouping Explanation

Substitution eligibility for the FC4UTCBAF4.0-BAG100 is determined by the following critical parameters:

Frequency: 4 MHz (exact match required)
Frequency Tolerance: ±30ppm (exact match required)
Frequency Stability: ±50ppm (exact match required)
Operating Mode: Fundamental (exact match required)
Operating Temperature Range: -20°C ~ 70°C (exact match required)
Load Capacitance: Series (exact match required)
Mounting Type: Through Hole (exact match required)

Two substitute parts meet these criteria. The FC4STCBAF4.0 differs in ESR (150 Ohms vs. 100 Ohms) and package variant (HC-49/US vs. HC-49/U), representing a near-equivalent with modified electrical characteristics. The MP04A from CTS-Frequency Controls maintains identical ESR and package specifications, providing a direct functional equivalent.

Parameter Comparison

Parameter	FC4UTCBAF4.0-BAG100	FC4STCBAF4.0	MP04A
Manufacturer	Fox Electronics	Fox Electronics	CTS-Frequency Controls
Frequency	4 MHz	4 MHz	4 MHz
Frequency Tolerance	±30ppm	±30ppm	±30ppm
Frequency Stability	±50ppm	±50ppm	±50ppm
ESR (Equivalent Series Resistance)	100 Ohms	150 Ohms	100 Ohms
Operating Mode	Fundamental	Fundamental	Fundamental
Operating Temperature Range	-20°C ~ 70°C	-20°C ~ 70°C	-20°C ~ 70°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package / Case	HC-49/U	HC-49/US	HC-49/U
Load Capacitance	Series	Series	Series
Product Status	Obsolete	Active	Active
RoHS Status	Not Specified	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

The MP04A from CTS-Frequency Controls is the preferred substitute for the FC4UTCBAF4.0-BAG100. Both parts maintain identical ESR specifications (100 Ohms) and HC-49/U package configuration, ensuring direct mechanical and electrical compatibility. The MP04A is currently in active production status with ROHS3 compliance certification and unlimited moisture sensitivity level rating, supporting long-term component availability and regulatory compliance.

The FC4STCBAF4.0 represents an alternative from the original manufacturer, Fox Electronics. This part maintains all critical frequency and operating parameters but introduces a 50 Ohm increase in ESR (150 Ohms) and uses the HC-49/US package variant. The FC4STCBAF4.0 is also in active production with ROHS3 compliance. Selection of this part requires circuit-level verification that the elevated ESR does not impact system performance.

Frequently Asked Questions (FAQ)

Q: Can the FC4STCBAF4.0 be used as a direct replacement for the FC4UTCBAF4.0-BAG100?

A: The FC4STCBAF4.0 maintains all critical frequency parameters (4 MHz, ±30ppm tolerance, ±50ppm stability) and operating temperature range. However, the ESR increases from 100 Ohms to 150 Ohms, and the package changes from HC-49/U to HC-49/US. Circuit verification is required to confirm that the higher ESR does not degrade system performance or introduce timing errors.

Q: What is the difference between HC-49/U and HC-49/US packages?

A: Both are through-hole crystal packages in the HC-49 family. The HC-49/U has a maximum seated height of 0.530" (13.46mm), while the HC-49/US has a maximum seated height of 0.142" (3.60mm). The HC-49/US is a lower-profile variant. Physical board layout and clearance requirements must be evaluated before substitution.

Q: Is the MP04A a direct equivalent to the FC4UTCBAF4.0-BAG100?

A: Yes. The MP04A matches all critical specifications: 4 MHz frequency, ±30ppm tolerance, ±50ppm stability, 100 Ohms ESR, HC-49/U package, and -20°C ~ 70°C operating temperature range. The MP04A is manufactured by CTS-Frequency Controls and is in active production with ROHS3 compliance.

Q: Why is the FC4UTCBAF4.0-BAG100 classified as obsolete?

A: The part is no longer in active production by Fox Electronics. Substitute parts must be identified for new designs or system maintenance. Both the FC4STCBAF4.0 and MP04A are actively manufactured alternatives.

Q: Are all substitute parts ROHS3 compliant?

A: The FC4STCBAF4.0 and MP04A are both ROHS3 compliant. The original FC4UTCBAF4.0-BAG100 RoHS status is not specified in the available documentation.

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