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One problem about XFC pin  capacitor on MPC8260A?

Question asked by meng junling on Jun 29, 2015
Latest reply on Oct 25, 2015 by meng junling

One problem aboutXFC pin  capacitor on MPC8260A?

 

I have debug the MPC8260ACZUMHB(266/166/66Mhz) succesfully, read PVR(00810101) and IMMR value(0024), the values indicate the chip is 0.29um(HiP3) version.

but now CPU changes to MPC8260ACZUMIB(266/200/66Mhz), the PVRand IMMR value(0062) indicate the chip is 0.25um(HiP4) version.

the same programm can't boot correctly, I try to change the XFC capacitor according MPC8260 Reference Manual, it still can't boot sucessfully, the UART(SMC1) outputs nothing.

 

XFC capacitor(0.25um)

min                                recommended                        max

MF*580-100                  MF*680-120                        MF*780-140

 

Aiso, I try to change core frequency and core voltage dependent on core frequency.

when core frequency is less than and equal to 200Mhz, the VDDL is set to 1.8V,

core frequency is greater than and equal to 233Mhz, the VDDL is set to 2.0V.

 

For example,

the frequency setting is 200/133/66, MF=2, XFC pin capacitor(1500pF), VDDL(1.8V).

or the frequency setting is 200/133/66,,MF=2, XFC pin capacitor(1500pF), VDDL(2.0V).

or the frequency setting is 266/166/66, MF=5, XFC pin capacitor(3500pF), VDDL(2.0V).

 

No matter which setting I select, the CPU can't boot succesfully, and UART outputs nothing.

 

Please help me to resolve the problem!

Thanks

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