MPC5604 decoupling capacitors

[卓儒陈]

I designed a device with MPC5604,I have not solder the decoupling capacitors between VDD_BV/VDD_LV and GND,then I power on the device and download a program use PE.

The first time it suspend unexpectly and all memory shows XX XX XX,after that I try to download again it shows can not enter background mode.

So I guess problem is the capacitors,am I right, or may be other problem lead to this result? And how can I do to recover the chip.Thank you.

My email address is [email protected]

[PetrS]

Hi,

The decoupling capacitor on VDD_BV/VDD_LV pins are definitely necessary to decouple internal regulators and to cover current peaks. So please check the device datasheet to know what capacitors should be placed there.

Typically, if an erase/program operation is interrupted due to a brownout, simply repeating the flash erase operation will recover the the flash memory block(s).

The only exception is shadow flash. Shadow flash contains censorship control words. If the shadow flash is erased and censorship control words are not restored before next reset, the chip will be locked forever. No way to recover. To overcome this problem, this workaround can be used; http://www.freescale.com/files/32bit/doc/app_note/AN3787.pdf. Sure must be used before it happens.

Regards,

Petr