shutoff Oscillator Watchdog(OWD) but still use the PLL fuction

[4310239955_st]

Posted on November 30, 2006 at 06:17

shutoff Oscillator Watchdog(OWD) but still use the PLL fuction

[4310239955_st]

Posted on May 19, 2005 at 07:08

Hello,

we are using the ST10R272 in our industrial controller.

We are working with a 11Mhz crystal and multiply this by 4 with the PLL-function.

If we test the controller in our EMC lab we can trigger a

OWD by applying ESD(electrostatic discharge) on to the controller.

(probably some PLL-pulses are being missing due to the high discharged voltage). Is there a possibility to shutoff the OWD-fuction but still use the PLL-funtion?

[4310239955_st]

Posted on May 19, 2005 at 08:34

Hello,

thanks for your quick reply!

We are not perturbing the entry of the PLL on purpose.

What we do is applying an electrostatic discharge(ESD) onto the housing of our industrial controller. Probably due to the internal tracking of our PCB's some of this ESD-signal is perturbing the PLL.

(Maybe the PCB-tracks of the crystal or too close to other PCB-tracks) We probably can solve this problem by re-tracking the PCB, but its not so easy to find out which tracks or causing this problem. That's why I was wondering if we can shutt-off this fail safe mechanism in software but can we than still use the PLL-function? In other words: can we use this PLL-function without the fail safe mechanism?

regards,

Jan

[najoua]

Posted on May 19, 2005 at 14:10

Hi,

When the OWD is disabled, the CPU clock is always fed from the oscillator input and the PLL is switched off.

[4310239955_st]

Posted on May 20, 2005 at 06:40

Good morning,

too bad, we will have to find another solution!

thanks for your help,

Jan

[4310239955_st]

Posted on November 30, 2006 at 06:17

A while ago I asked a question about the OWD function (see previous questions) We have redesigned the PCB and are now using an external Oscillator of 44.2368MHz. We have disabled the OWD function in software.

To test this I've removed the input oscillator signal from the ST10 but

we still get the PLL unlock error. Do you have any idea what we are doing wrong? Normally with the OWD disabled the PLL should be turned of!?!