Why Engineers Calculate Crystal Load Capacitance

Powering your ECS Inc. component for balanced, clean performance requires engineers to consider load capacitance and resistance. Experiment with values for optimal crystal load capacitance and identify the most accurate and stable signal.

To calculate the capacitive values for CL1/CL2 and Cs, we need the follow:

  1. Load capacitance of the crystal as stated on the Manufacturers datasheet.
  2. Estimated or measure the stray capacitance on your PC board. Typically, 2 ~ 5pF
  3. The calculated values given for CL1 and CL2 are mathematic. You will need to find the nearest standard value capacitors to the required value.

Example:
Crystal CL = 15pF = 
Cs – 2pF
(CL1 & CL2) and 2pF stray = (CS).

CL1 = CL2 =2(15 – 2)
15 – 2 = 13pF
13 x 2 = 26pF.
You will need two capacitors of this value to balance the circuit.

Need help determining an estimate for board resistance? ECS Inc. provides engineering support to ensure your product is ready for your innovative use case.