About External Crystal Circuit for MKW01

[luws]

Hi dear,

I design a MKW01Z128CHN board refer to KW01-9032 demo board and MKW01 datasheet Chapter 9 " Typical Applications Circuit", with a oscillation circuit including a 32MHz crystal (100ppm, 3225), two 11pF capacitance (C7 and C4, 0402).  I use 265 degrees heat gun to solder the MCU and crystal manually. Then I found the clock circuit do not work as followed:  

1. When I use J-Link, most time it cannot connect to target. Only a few times I can flash the code into the target. When I use debug function, after download the code, it cannot start working.

2. When the MCU work standalone without J-Link, most time the crystal cannot start oscillation. Some time I touch the board can start the oscillation and the MCU will work OK. 

Besides, I found VR_DIG and VR_ANA have no stable output.

Can you help me to analyze the phenomenon: Is it (1) because of my solder artwork? Or (2) because of the parameter of C21 and C22? Or (3) because of my PCB layout trace of oscillation circuit?

The schematic diagram and PCB layout are as attached, together with KDS Jlink config. 

Thanks a lot! Looking forward to your reply.

[mario_castaneda]

Hi Wenshaui,

Besides, I found VR_DIG and VR_ANA have no stable output.

This output value is not recommended for reference on your circuit.

Mario

[luws]

Hi Mario,

Thank you for your reply.

OK, I will not use these pins for reference.

Finally, I found my crystal cap load is 18pF, and need two 24pF for external loads. I also tune down solder temperature at 260 degrees, to replace a new MKW01 chip. Now the circuit works well.

Can I have your e-mail address for further discussion? My e-mail is luws@mail.tsinghua.edu.cn

Thanks.

[mario_castaneda]

Hi Wenshuai,

You can request support following the next link

Support|NXP 

Regards,

Maro