9B-3.6864MAAJ-B Crystal Equivalent & Substitute Parts

Part Overview

The 9B-3.6864MAAJ-B is a 3.6864 MHz through-hole crystal oscillator manufactured by TXC CORPORATION, designed for fundamental mode operation with 18pF load capacitance and 150 Ohms equivalent series resistance (ESR). This component operates across the temperature range of -20°C to 70°C with ±30ppm frequency stability.

The 9B-3.6864MAAJ-B is classified as obsolete. Identifying equivalent substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this crystal frequency and package specification.

Key Parameters

Parameter	Value	Significance for Substitution
Frequency	3.6864 MHz	Critical - must match exactly for circuit timing
Frequency Stability	±30ppm	Critical - determines timing accuracy
Load Capacitance	18pF	Critical - must match for circuit resonance
ESR (Equivalent Series Resistance)	150 Ohms	Important - affects oscillator startup and power consumption
Operating Mode	Fundamental	Critical - determines frequency generation method
Package / Case	HC-49/US	Critical - must match for mechanical and electrical compatibility
Mounting Type	Through Hole	Critical - determines PCB assembly method
Operating Temperature Range	-20°C ~ 70°C	Important - must support application environment

Substitute Part Grouping Explanation

Substitute parts for the 9B-3.6864MAAJ-B are identified based on strict electrical and mechanical parameter matching. The following criteria determine substitution eligibility:

Critical Matching Parameters:

Frequency: 3.6864 MHz (exact match required)
Load Capacitance: 18pF (exact match required)
Package / Case: HC-49/US (exact match required)
Mounting Type: Through Hole (exact match required)
Operating Mode: Fundamental (exact match required)
Frequency Stability: ±30ppm (exact match required)
Operating Temperature Range: -20°C ~ 70°C (minimum requirement)

Allowable Variation Parameters:

ESR (Equivalent Series Resistance): Variation permitted within component design tolerances
Physical dimensions: Minor variations acceptable within HC-49/US package specification
Manufacturer: Different manufacturers acceptable if all electrical parameters match

The HC49US-FF3F18-3.6864MHZ manufactured by ILSI qualifies as a substitute based on matching all critical parameters while maintaining functional equivalence.

Parameter Comparison

Parameter	9B-3.6864MAAJ-B (TXC)	HC49US-FF3F18-3.6864MHZ (ILSI)	Match Status
Frequency	3.6864 MHz	3.6864 MHz	Exact Match
Frequency Stability	±30ppm	±30ppm	Exact Match
Frequency Tolerance	±30ppm	±30ppm	Exact Match
Load Capacitance	18pF	18pF	Exact Match
ESR (Equivalent Series Resistance)	150 Ohms	200 Ohms	Variation - Within Tolerance
Operating Mode	Fundamental	Fundamental	Exact Match
Operating Temperature Range	-20°C ~ 70°C	-20°C ~ 70°C	Exact Match
Mounting Type	Through Hole	Through Hole	Exact Match
Package / Case	HC-49/US	HC-49/US	Exact Match
Size / Dimension	0.453" L x 0.197" W (11.50mm x 5.00mm)	0.437" L x 0.185" W (11.10mm x 4.70mm)	Within Package Specification
Height - Seated (Max)	0.145" (3.68mm)	0.138" (3.50mm)	Within Package Specification
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Exact Match

Engineering Selection Recommendations

Primary Substitute: HC49US-FF3F18-3.6864MHZ (ILSI)

The HC49US-FF3F18-3.6864MHZ is functionally equivalent to the 9B-3.6864MAAJ-B for applications requiring a 3.6864 MHz crystal with 18pF load capacitance in HC-49/US through-hole package format.

Compliance Considerations:

Both parts maintain ROHS3 compliance, supporting environmental regulatory requirements
Both parts are classified under identical HTSUS code 8541.60.0030
Both parts carry EAR99 ECCN classification

Product Status Advantage: The HC49US-FF3F18-3.6864MHZ is classified as Active, providing superior long-term supply chain availability compared to the obsolete 9B-3.6864MAAJ-B. Current inventory of 1594 pieces supports immediate procurement requirements.

ESR Consideration: The HC49US-FF3F18-3.6864MHZ exhibits 200 Ohms ESR compared to 150 Ohms in the original part. This 50 Ohm increase remains within acceptable operating parameters for HC-49/US crystal applications and does not compromise circuit functionality when the oscillator circuit is properly designed for the specified load capacitance.

Frequently Asked Questions (FAQ)

Q: Can the HC49US-FF3F18-3.6864MHZ directly replace the 9B-3.6864MAAJ-B without circuit modification?

A: Yes. Both crystals operate at identical frequency (3.6864 MHz), load capacitance (18pF), frequency stability (±30ppm), and temperature range (-20°C ~ 70°C). The 50 Ohm ESR difference does not require circuit redesign when the oscillator is designed for 18pF load capacitance operation.

Q: What is the significance of the ESR difference between the two parts?

A: ESR (Equivalent Series Resistance) affects oscillator startup behavior and power consumption. The HC49US-FF3F18-3.6864MHZ at 200 Ohms versus the original 150 Ohms represents a 33% increase. For properly designed oscillator circuits with adequate drive capability, this variation remains within acceptable operating margins for HC-49/US package crystals.

Q: Are both parts physically compatible with existing PCB designs?

A: Both parts use HC-49/US through-hole package format with compatible pinout. Physical dimensions vary slightly within package specification (original: 11.50mm x 5.00mm; substitute: 11.10mm x 4.70mm). Both fit standard HC-49/US footprints without modification.

Q: What is the supply status difference between these parts?

A: The 9B-3.6864MAAJ-B is obsolete with 799 pieces in stock. The HC49US-FF3F18-3.6864MHZ is active with 1594 pieces available, providing superior long-term availability for ongoing production.

Q: Do both parts meet the same regulatory requirements?

A: Yes. Both parts are ROHS3 compliant and carry identical HTSUS classification (8541.60.0030) and ECCN designation (EAR99).

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message