Dapu Microelectronics Crystal Oscillators (XO)

Dapu crystal oscillators support a wide frequency range from 1MHz to 200MHz for standard products. Low-frequency oscillators (32.768kHz) are available for real-time clock applications. High-frequency options up to 1.5GHz are available in PLL-based clock generators. The most common frequencies include 8MHz, 12MHz, 16MHz, 24MHz, 25MHz, 48MHz, and 50MHz for microcontroller and processor applications. Communication frequencies include 25MHz and 125MHz for Ethernet, 26MHz and 38.4MHz for cellular, and various frequencies for video and display applications. Custom frequencies can be programmed for volume orders.

Select standard frequencies for cost savings, custom frequencies for specific requirements. Contact us for custom frequency availability.

Dapu oscillators are available in various package options to meet different application requirements. Standard SMD packages include 2.0x1.6mm, 2.5x2.0mm, 3.2x2.5mm, 5.0x3.2mm, and 7.0x5.0mm ceramic packages. Smaller packages (1.6x1.2mm) are available for space-constrained applications. DIP packages (Half-size, Full-size) are available for through-hole mounting. Specialized packages include ceramic SMD with metal lids for better EMI performance. Automotive-grade packages meet AEC-Q200 requirements. The package selection affects cost, board space, and thermal characteristics. Smaller packages typically cost more but save PCB area.

Choose package based on board space constraints and cost budget. Standard 3.2x2.5mm offers good balance of size and cost.

Dapu crystal oscillators offer competitive jitter performance suitable for most applications. Standard XOs typically achieve 1-3ps RMS phase jitter (12kHz-20MHz integration range), adequate for general-purpose clocking. Low-jitter versions achieve <1ps RMS for high-speed SERDES and communication applications. Period jitter is typically <100ps peak-to-peak. The jitter performance depends on crystal quality, oscillator circuit design, and power supply noise. For applications requiring ultra-low jitter (<0.5ps), consider Dapu's premium low-jitter series or clock generators with integrated jitter attenuation. Phase noise plots are available for critical applications.

Select standard XO for <3ps jitter requirements, low-jitter series for <1ps requirements. Contact us for phase noise data.

Load capacitance (CL) is critical for crystal oscillator frequency accuracy. The total load capacitance seen by the crystal is calculated as: CL = (C1 * C2) / (C1 + C2) + Cs, where C1 and C2 are the external load capacitors, and Cs is the stray capacitance (typically 3-5pF). For example, if CL specification is 20pF and Cs is 4pF, then (C1 * C2) / (C1 + C2) = 16pF. If C1 = C2, then each capacitor should be 32pF. Dapu oscillators specify the required load capacitance in the datasheet. Using incorrect load capacitance causes frequency offset. Most Dapu oscillators have built-in load capacitors and don't require external calculation - check the datasheet for specific part numbers.

Use Dapu oscillators with built-in load caps to simplify design. For discrete crystals, follow the calculation formula above.

Dapu oscillators can drive multiple loads depending on output type and fanout capability. CMOS output oscillators can typically drive 10-15 standard CMOS loads (15pF each). For driving multiple loads, use a clock buffer or place loads close to the oscillator to minimize trace capacitance. LVCMOS outputs provide better drive capability than clipped sine outputs. For high fanout applications (>20 loads), use a dedicated clock distribution chip or zero-delay buffer. Differential outputs (LVDS, LVPECL) can drive multiple loads through proper termination. When driving multiple loads, ensure total capacitance doesn't exceed the oscillator's drive capability as specified in the datasheet.

For multiple loads, use clock buffers or place loads close to oscillator. Contact us for high fanout solutions.