AEC-Q200 28 MHz crystal for automotive and thermal environments
The ECS-286.3-12-33Q-JES-TR: The ECX-33Q at 28.63636 MHz carries AEC-Q200 qualification, which means it passed the automotive stress tests — temperature cycling, board flex, and moisture resistance — required for safety-critical and under-hood assemblies. ±20 ppm frequency tolerance at room temperature plus ±50 ppm stability over the full temperature range keeps the accumulated timing error inside the UART baud-rate budget for CAN-FD and LIN nodes — most automotive MCUs tolerate ±1 % clock error, and this crystal holds roughly a tenth of that across the operating band.
4-SMD package and clock-source fit
The no-lead (QFN-style) construction reduces lead inductance compared to a hermetic HC-49 package, which matters at 28 MHz because the crystal's series resonance sits well above the fundamental crystal bandwidth where shunt capacitance dominates. 40 Ω ESR at 28.63636 MHz is typical for this frequency and load capacitance. The MCU's oscillator gain (gm) must exceed the crystal's motional resistance by a comfortable margin for reliable startup — check the MCU's crystal driver specification against this ESR to confirm start-up margins, particularly at cold temperatures where ESR rises.