Cap load settting of K32L2A41VLL1A for cap other than 2 pF, 4 pF, 8 pF, 16 pF

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Cap load settting of K32L2A41VLL1A for cap other than 2 pF, 4 pF, 8 pF, 16 pF

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jainish
Contributor II

Hi, I am using k32l2a41vll1a custom board. For external crystal's (ABS07- 32.768 kHz) capacitor load configuration, SCG_SOSCCFG register is provided and available capacitor load configuration for that register are 0 pF, 2 pF, 4 pF, 8 pF, 16 pF. 

jainish_0-1717140032145.png

 

And for FRDM-K32L2A4S, crystal has 12 pF load capacitor (DNP) and I have used same cap value in my custom board. But no configuration for 12 pF is there in SCG_SOSCCFG.

Please suggest proper configuration of SCG_SOSCCFG for 12 pF.

Currently I have have used 0 pF setting, is it valid or not?

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Pavel_Hernandez
NXP TechSupport
NXP TechSupport

Hello, my name is Pavel, and I will be supporting your case, I reviewed the Datasheet chapter 9.1.5 Crystal Oscillator, maybe this could help you.

"Internal load capacitors (Cx, Cy) are provided in the low frequency (32.786kHz) mode.
Use the SCxP bits in the SCG_SOSCCFG register to adjust the load capacitance for the
crystal. Typically, values of 10 pf to 16 pF are sufficient for 32.768 kHz crystals that
have a 12.5 pF CL specification. The internal load capacitor selection must not be used
for high frequency crystals and resonators. See crystal or resonator manufacturer's
recommendation for parameters about load capacitance and RF."

Best regards,
Pavel

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