RE : 32.768 kHz Crystal Oscillator

[Roshan Prajapati]

Hi,

We have designed the custom PCB where 32.768 kHz crystal oscillator is required. Some how we have managed the component (MFR PART NO. TF325J32K7680) suggested by Nordic team for our initial (development stage) custom board.

Now we would require this same component in bulk for production. Unfortunately, there is no stock of TF325J32K7680 crystal oscillator but we have managed to find the alternate component which is having same frequency 32.768 kHz. But, Load capacitance is varying.

I just want to know, whether we can use the alternate component which is having capacitance around 12.5pF. Find the below configurations of original and alternate component and let me know we can use this alternate Crystal or not.

NOTE: Our board is designed based on original crystal suggested by Nordic team.

Original:

Alternate:

Best Regards,

Roshan.

[Jared]

Hi, 

I just want to know, whether we can use the alternate component which is having capacitance around 12.5pF

 You can use it, but you would have to adjust the parallel load capacitors to 21 pF.

regards

Jared

[Roshan Prajapati]

Hi Jared,

Thanks for your response. Are you talking about the below parallel load capacitors C20 & C23? If yes, then both C20 & C23 should have 21 pF or 21pF by summing both capacitors? This question may be silly but, I have no idea on this. Kindly, help me out.

Best Regards,

Roshan R.

[Jared]

Hi, 

Roshan Prajapati said:

then both C20 & C23 should have 21 pF

This is the correct one. 

regards

Jared 

[Roshan Prajapati]

Jared said:

This is the correct one

Ok Jared. Thank You So much!!

[Jared]

No, problem. FYI: we offer free design reviews, which means that one of our HW engineer will review your schematic and PCB layout file and comment on anything that should be changed. Just create a new private ticket and add your design files for a design review.

regards

Jared