QT49S-3.6864MAHJ-T

Overview

The QT49S-3.6864MAHJ-T is a surface-mount quartz crystal resonator manufactured by QST, operating at a fundamental frequency of 3.6864 MHz. It features a frequency tolerance and stability of ±30 ppm at 25°C. The component utilizes an 18 pF load capacitance and exhibits an equivalent series resistance (ESR) of 150 Ohms. Designed for base mode operation, it supports a wide operating temperature range from -40°C to +85°C. The physical package is HC-49/US style with SMD termination, measuring 12.7 mm in length, 4.8 mm in width, and 3.8 mm in height. It is RoHS3 compliant and classified under MSL Level 1.

Feature Summary

• Surface-mount construction in HC-49/US form factor
• High frequency stability within ±30 ppm tolerance
• Wide industrial temperature range capability
• Base mode fundamental resonance operation

Applications

• Microcontroller clock sources
• Real-time clock circuits
• Communication interface timing
• Embedded system oscillators

Procurement Notes

Verify the specific suffix 'MAHJ-T' against official QST documentation to confirm the exact pin configuration and termination type. Ensure the selected variant matches the required load capacitance of 18pF for circuit compatibility. Cross-reference the datasheet for any recent revisions that may impact mechanical dimensions or electrical parameters before finalizing procurement.

Selection Notes

Select this component when a standard HC-49/US footprint is required in a surface-mount design. The 150 Ohm ESR value must be compatible with the oscillator circuit's drive level requirements. Consider the ±30 ppm stability sufficient for general digital logic timing but verify if tighter tolerances are needed for precision applications. Ensure the operating environment stays within the specified -40°C to +85°C range.

Part Context

This part belongs to the QT49S series of quartz crystals from QST. The series offers various frequencies and packages, with the MAHJ-T suffix denoting specific SMD termination characteristics. It serves as a direct replacement for through-hole HC-49/US crystals in modern PCB layouts requiring reduced profile and automated assembly compatibility.

Replacement Considerations

Public confirmed substitute part numbers include QT49S-3.6864MAGJ-T and QT49S-3.6864MAAJ-T. Verify that these alternatives maintain identical electrical parameters, specifically the 18pF load capacitance and 150 Ohm ESR, before substitution.