Brown Outs and Microcontroller ICs

No such thing as far as I'm concerned.
A voltage dip may be low enough to cause the microcontroller to do a reset, or negative spikes on the supply may reset it. (Hysteresis would normally stop it bouncing on/off repeatedly although some of my software produces a similar effect)

A micro controller is a digital device...thus 'brownout' with it's implied reduced voltage/performance ins't possible... The micro is either on or off.

I'm willing to be corrected if someone has found a micro which has logic states 0,1 and 0.75

Del

I'm willing to be corrected if someone has found a micro which has logic states 0,1 and 0.75

Really confuse them and make it 0.1001011

I agree with Del. It either has it or it "Don't"

It is possible for a low voltage state on a microcontroller to cause portions of the internal circuitry to malfunction. This would most likely cause the system to lock up and need a reset. Some older ICs used to have issues with low power causing them to work inefficiently and potentially causing the IC damage, but I haven't heard of that in a very long time.

The best bet in an undervoltage situation with a microcontroller is just have an automatic shutdown and reboot the chip when the power comes back to normal. Better yet, regulate the power supply better.

Good luck,

Doug

Microcontrollers are implemented with MOS transistors that have a minimum required gate voltage to turn on the transistor. So below a certain voltage the transistors will not be properly on which then of course means the digital state become ambiguous at some point and operation can become erratic and unpredictable.

Many manufacturers put a brown out detect circuit to hold the controller in reset below a certain operating voltage to prevent erroneous operation. There are also external reset generators that can do the same below a preset threshold voltage.

Tell us which IC so I can look at the datasheet where the answer will be given.

The first 68HC11 could reprogram their registers if the power was brought up or down too slow. Search for LVI in http://www.mil.ufl.edu/imdl/papers/IMDL_Report_Fall_96/Jeff_Webb/final.pdf

The memory could become unstable at 4volts. I have seen it happen on one board. I expect most CPU's do it internanly now days.

Gordon