Hi all,

Our 7S board has low slew rate power supply which has 1V/Sec.
It fail boot some time and then it can't re-start by reset button.
it can only start by off-on power supply.

Also, schematic check list document of ATMEL is recommending
6V/ms high slew rate supply.
But in real world , if entire circuit has heavy load capacitor , it can
disturb slew rate of power supply.

I've debugged in PLL setup routine in startup code of IAR compiler.
but I can't solve this problem.
I guess the Slow Clock Oscillator failed oscillation on low slew rate power input. but i can't probe whether it fail or not.

How can i probe operation of the Slow Clock Oscillator ?


Thanks,
K.S.Lee

hello,
bad news for you: the 6v/ms is a must.
your power supply has to fulfill this requirement, there is no workaround!

take a look at the first issue if this link:
http://support.atmel.no/bin/customer?=& ... try&id=726

regards
gerhard

Thank you for your advice.

I decided compensation circuit for low slew rate power supply.

simple Reset IC + LDO built in Enable pin.

if reset ic has 3V threshold voltage, it can control LDO
for correct slew rate power supply.

low slew rate environment is suggested for SAM7S and MSP430 both.

best regards,
K.S.Lee