Hi,
F5324 faced one problem from customer site, when XT2 12MHz (passive) is used for MCLK, the system can not pass ESD 8KV, group pulse 2KV. Reset and crash always happen.
But in these cases, F5324 can pass:
1) Internal DCO instead of XT2;
2) XT1 32K;
3) XT2 active 12MHz.
Note: XT2 is the only solution for customer funtion request. The PCB is small size.
Hope to get your support.
Regards,
Jordan
I don't think there is a solution.
In all cases where the device passes the 8kV test, MCLK is either driven by internal DCO or by a stable external clock signal.
In case of the 12MHz passive XT2 (a crystal), the ESD causes the crystal to turn into an e.g. 48MHz crystal for one cycle. Which will of course crash the MSP.
A possible solution would be to use a 24MHz crystal isntead and use a /2 divider for MCLK. THen MCLK will be the averaged result of two crystal cycles (4 would be even better, but I don't knwo whether an 48MHz crystal can be used at all) and the result will likely be still in the allowed operating range.
BTW: the same problem can happen when you switch teh RSEL value for the DCO: one erroneously short clock cycle that may crash the MSP. Solution is the same: use a MCLK divider during the switch)
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Jordan Zhou Hi, F5324 faced one problem from customer site, when XT2 12MHz (passive) is used for MCLK, the system can not pass ESD 8KV, group pulse 2KV. Reset and crash always happen.
Hi Jordan, ESD failure can result from a set of different path, if all part of circuits are ok I can think about ungrounded XTAL case or bad layout around xtal pins coupling EMF to oscillator tracks. To be of some help the layout of ground and oscillator tracks are needed to inspect for weak ESD/EMF screening.
Regards
Roberto
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Thanks for your reply. I'll try with 24MHz and 2 divider.
Can you help to provide some info about MSP430F5xx and MSP430F2xx XT2 difference.
As I know, the voltage amplitude on F247 XT2 is over 1V; while F5324 is lower than 0.5V. Why is the difference?
Thanks.