MPC5534 Latches at -30C

[bonzo]

I have a customer that has a re-design of a board using the MPC5534.

The previous version used a 10MHz crystal and internal PLL for 70MHz and 80MHz operation.  It functions over the entire temperature range with no failures down to -40C.

The new design uses an external 80MHz oscillator fed to XTAL and run in PLL-bypass mode.  At -30C, the part halts.  As it cools down, the output clock at ENGCLK starts to slow down until it stops.

Questions:

1.  Is it acceptable to drive EXTAL with a 3.3V  (assuming VDDES = 3.3V).  Or does the signal need to be attenuated or series resistor and/or capacitor coupling?

2.  Are Erratas e1151 and e488 applicable to using an external Oscillator? (see attached)

3.  Can we find out if what Fz and type of clock is used in the manufacturing test program by the ATE? 

--Brad

[lukaszadrapa]

Hi Brad,

1. From RM:

External components are not needed.

2. e1151 is something different. e488 talks about unintentional switch to bypass mode. As you want to use bypass mode, this erratum is not applicable.

3. I will try to ask around for more details.

I guess that the external oscillator works without any issues down to -40C and its output signal meets the specs at this temperature, right?

Regards,

Lukas

[bonzo]

The external 80MHz oscillator functions fine at -40C.

Customer has changed the Abacom oscillator to 12MHz in bypass mode and works down to -40C.  Next step is to use PLL to boost up to 80MHz, so does e488 apply?

[lukaszadrapa · Accepted solution]

PLL can't be used in bypass mode. It is turned off.

e488 applies when the configuration pins are used as GPIO (or other alternate function) in application. If the pins are used just for configuration, so they are only connected to pull-up or pull down-resistor all the time, then the e488 does not apply. Take a look at:

http://www.nxp.com/files/microcontrollers/doc/app_note/AN2613.pdf

Lukas