In SX Microcontrollers, SX/B Compiler and SX-Key Tool, tdodds wrote:

I have recently gotten several SX18s to use in some industrial control applications. The first project I have working is a PWM motor controller. It works just fine, except that I occasionally have been having problems with software lockups during testing. With further investigation, I have found that if the power supply voltage is lowered from normal operaton to between 1.4 and 1 volt and then raised again, the processor will lock up every time. If the voltage is lowered to zero and then back up, the processor resumes operation. This will cause a problem on a power glitch if the duration is just the right width to discharge the power supply capacitor to 1.4 volts but not to zero (I have verified this on four different SX18 chips). This doesn't happen on the SX28, and I don't have any SX20s on-hand to try. It behaves this way on my software or on just a four line LED-blink program.

Has anybody seen this problem before, or know of a simple (cheap) circuit that will knock the voltage to the processor to zero if the voltage drops below 4 volts or so (a workaround)???

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