Hi all,

We have been using the following microcontroller (LPC3250FET296/01) for awhile from NXP. We currently seeing failures during our thermal test at 70C and sometimes fails at ambient temperature. Anyone has any suggestion on why the controller would reboot itself at certain temperature? What are potential causes for the controller to reboot/resetting? Any suggestions would be greatly appreciated.

Thanks,
WJ

 

hi WJ,
One possible cause is that if the internal oscillator fails due to the high temperature.
Have you tried a test by keeping the MCU cooled, with say a freezer aerosol spray.?
E

 

What is the microcontroller connected to when it fails?

 

What is the microcontroller connected to when it fails?

Hi,

Thanks for the reply. The microcontroller connects to a PC running a script that monitors whenever microcontroller is alive.

 

hi WJ,
One possible cause is that if the internal oscillator fails due to the high temperature.
Have you tried a test by keeping the MCU cooled, with say a freezer aerosol spray.?
E

Hi,

Thank you for your reply. We have used the freezer spray and works sometimes.

 

How is the reset pin connected?

 

Hi,

Thanks for the reply. The microcontroller connects to a PC running a script that monitors whenever microcontroller is alive.

What is the micrcontroller's power source? Have you checked that it is clean and stable? is it powered from the computer USB?

 

What is the micrcontroller's power source? Have you checked that it is clean and stable? is it powered from the computer USB?

So far the power source is clean and stable, the board (microcontroller) is powered via wall adapter using LDO to power the microcontroller.

 

So far the power source is clean and stable, the board (microcontroller) is powered via wall adapter using LDO to power the microcontroller.

Have you checked the power at the pins of the microcontroller while under test? Heating the board including the LDO will reduce the power dissapation abilities of the LDO and maybe it is going into thermal shutdown under load.

 

So far the power source is clean and stable, the board (microcontroller) is powered via wall adapter using LDO to power the microcontroller.

1) If enable pins on the micro are not connected (floating), they work sometimes and randomly cut out. Make sure all pins are connected correctly for reliable function

2) did you accidentally enable the watchdog timer and, if so, have no regular reset routine?

7.7.2 Watchdog timer
The watchdog timer block is clocked by the main peripheral clock, which clocks a 32-bit counter. A match register is compared to the Timer. When configured for watchdog functionality, a match drives the match output low. The match output is gated with an enable signal that gives the opportunity to generate two type of reset signal: one that only resets chip internally, and another that goes through a programmable pulse generator before it goes to the external pin RESOUT and to the internal chip reset.

3) does your project have an inductive load without appropriate diode protection?

4) are you driving any heavy loads that may be causing your supply voltage to sag?

5) is any pin in the micro carrying too much current and causing a shutdown? Be sure to have current limiting resistors on all pins (even if connected to a capacitive load or a Mosfet gate).