What is Load Capacitance of A Crystal
When Designing circuits and while reading the datasheet of crystals, it usually talks about load Capacitance. Please help me to understand the function of load Capacitance and how it affects the oscillating circuit in my design. Usually it's rated in pico farads. What happens to the crystal if a load Capacitor is not added.
Solution:Jump to solution
load capacitors are not optional component; they are a fundamental part of the crystal oscillator design.
7 Replies
@pallavaggarwal @Petr Dvořák @Joseph Ogbonna, can you people help me clarify this.
The load capacitance ensures the optimal impedance condition of the crystal. The load capacitance is not only the chip capacitor device itself, but you need to calculate both trace capacitance and parasitic load capacitance of the IC input.
Without correct load capacitance, the crystal can be unstable and sensitive to outer conditions.
Solution
load capacitors are not optional component; they are a fundamental part of the crystal oscillator design.
They ensure that the oscillator operates at the correct frequency with stability and reliability, factors that are critical in most applications that require precise timing, such as microcontrollers, communication interfaces(USB, BLE), and digital clocks.
The specific value of the load capacitors is usually provided by the crystal manufacturer.
Do this mean that if am meant to use a cap of 12pF and i eventually use 8pF that the oscillation wont be stable
oo great, I get it now. I thought before that there is a default value we can use, like 12pF or 15pF.
I use the following calculation
wow, thanks for the information