19.6608 MHz fundamental — clock crystal for industrial embedded designs
The ECS-196.6-18-23A-EN-TR: The ECX-64A series crystal at 19.6608 MHz is a surface-mount fundamental-mode unit specified with an 18pF load capacitance — the most common load rating for UART, SPI-bus, and RTC reference clocks in 3.3V MCU and SoC designs.
±80 ppm total frequency budget — where the tolerance and stability stack
The ±30ppm initial tolerance and ±50ppm frequency stability combine for roughly an ±80ppm total frequency budget across temperature. For a UART running at 19.6608 MHz, that worst-case deviation stays within the standard ±1.5% baud-rate error limit across the full operating temperature range — but a design targeting sub-0.5% timing margin at temperature extremes should run a bench verification at temperature before locking the BOM. Equivalent Series Resistance is listed at 60 Ω, which sets the drive level the oscillator circuit must supply to keep the crystal in series resonance. Most MCU internal oscillators comfortably drive a 60 Ω crystal at the standard 100 µW drive level — but connecting this to a high-gain Pierce oscillator without checking the oscillator's recommended crystal ESR range is the most common cause of intermittent start-up failures in production spin.
2-SMD no-lead package — footprint and profile for dense board layouts
Land-pattern tolerance on the two mounting pads is forgiving compared to a true QFN with a centre thermal pad — solder-volume control matters more than pad geometry for a reliable reflow joint on this footprint. Fundamental-mode operation means the crystal oscillates at its natural resonant frequency with no overtone suppression needed — simpler oscillator circuit, lower component count, and better phase-noise performance than an overtone-stabilised design at this frequency. The 19.6608 MHz fundamental sits well within the range where the third-overtone would be the nearest spurious mode, far enough in frequency that it does not pull the fundamental.
Packaging and reel handling — Tape & Reel versus Cut Tape
Supplied on Tape & Reel (TR) with a Cut Tape (CT) option, the part ships on a standard 7- or 13-inch reel compatible with standard SMT pick-and-place feeders. The 2-SMD no-lead construction has a moderate moisture-sensitivity level — before reflow, a bake or dry-bag seal protocol consistent with the assembly house standard is the prudent call if the reel has been open longer than the floor-life limit for the package.