S12XHY128 self clock and PLL

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S12XHY128 self clock and PLL

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binli
NXP Employee
NXP Employee

Hi:

 

As S12XHY series, we have self clock mode: if CME=1 and SCME=1. But i test with customer board, found that if adding some interference, it seems that can make both Oscillator circuit and PLL circuit down. Means that when CM check there is unstable in Osc. and try to swtich to self clock mode, but found there is some problems for PLL and MCU goes down. So result in MCU broke dowm.

 

Is it possible? Thanks.

If yes. And i guess the interference goes through VDD/SS PLL. I check the RM and found that

'9.2.7 VREGEN—Optional Regulator Enable Pin
This optional signal is used to shutdown VREG_3V3. In that case, VDD/VSS and VDDPLL/VSSPLL
must be provided externally. Shutdown mode is entered with VREGEN being low. If VREGEN is high,
the VREG_3V3 is either in Full Performance Mode or in Reduced Power Mode.
For the connectivity of VREGEN, see device specification.'

I want to supply VDD/SS PLL externally. Do you know how we can set VREGEN? Although i guess may be it shouldn't open to customer. I hope can get some clue from you. Thanks.

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iggi
NXP Employee
NXP Employee

Hi Box,

It would be good if you can share the schematic and layout, or just part of it which is critical for this issue.

Also, we would like to check the clock configuration in your SW application.

Then we can move on with the investigation.

If you cannot share this publicly, follow the instruction in below guide to open a ticket:
How to submit a new question for NXP Support 

Regards,

iggi

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