ABLSG-4.000MHZ-D2Y-T is a 4.000 MHz fundamental-mode AT-cut crystal oscillator housed in a low-profile HC/49US (AT49) surface-mount package with a grounded third lead for EMI mitigation. The device features a compact form factor of 11.4 × 4.7 × 4.2 mm and is hermetically sealed with no moisture sensitivity (MSL = N/A). It operates over a temperature range of 0°C to +70°C with frequency stability of ±30 ppm over the operating temperature range (referenced to +25°C), and maintains a frequency tolerance of ±20 ppm. The crystal exhibits an equivalent series resistance (ESR) of 180 O, a shunt capacitance of 7 pF maximum, and a load capacitance of 18 pF, with a typical drive level of 100 µW. This grounded-lead design makes it ideal for EMI-sensitive applications including computers, modems, microprocessors, medical electronics, and wireless systems, while the IR-reflow capability and tight stability ensure reliable performance in modern manufacturing environments.