Circuit board assembly, circuit board design, and circuit board processing manufacturer explain whether the capacitance of circuit board design is close to the chip or the crystal oscillator is close to the chip
Ask how to place the crystal oscillator when it is not required to be far from the CPU, and whether it has any special requirements for wiring??
Of course, the closer you are to the CPU, the better. Don't take important signal lines under the crystal oscillator. It is an interference source. The clock signal should not be perforated as much as possible. The clock signal should not cross the division plane. These factors will cause impedance changes, whICh will affect the signal quality. It is also better to cover the copper surface of the ground network of the crystal oscillator...
It is better for the crystal oscillator to be close to the cpu, because it can ensure the shortest routing (to form a differential line), and the adjacent layers below the crystal oscillator should not have signal lines passing through...
It should also be noted that it should not be too close to the edge of the board.
The crystal oscillator (quartz crystal resonator) is closer to the chip (for those with high frequency accuracy requirements, the closer the better), because the distribution parameters of the circuit board will affect the accuracy of the frequency.
The resonant frequency of the oscillating circuit is closely related to the capacitance (calLED the load capacitance of the crystal) equivalent between the quartz crystal resonator pins, and its change will directly cause the resonant frequency change of the oscillating circuit.
The closer to the CPU, the better. It is also good to consider the process, whether there is interference between components, and whether it is convenient to weld. The inductance and capacitor of the crystal oscillator shall be close to its power supply pin as far as possible. The wiring shall be short and straight as far as possible, and no via shall be allowed. Finally, it can be processed in a three-dimensional way. In case of crystals, pay attention to the placement of capacitors and the grounding of differential wiring.
Of course, the shorter the wiring, the better.
Modular design: Capacitor and crystal oscillator are a module that should be closer. As a part of the clock of the microcontroller (crystal oscillator and capacitor module), the design requirements should be stricter. Try to determine the position at the beginning of the design, and pay attention to shielding interference to a certain extent. The distance between the microcontroller and the clock module should be closer. If the clock is far away, the clock is unstable and it is easy for the crystal oscillator to fail to vibrate. The circuit board assembly, circuit board design, and circuit board processing manufacturers explain whether the capacitance of circuit board design is close to the chip or the crystal oscillator is close to the chip.