I accidentally connected power to atmega32 reversed(VCC to ground and GND to 5v) after that the chip didn't work correctly any more , I noticed that ground and vcc pins of atmega32 chip are shorted.
Is the chip gone or there is some kind of a
solution?
Atmega32 VCC and GND pins shorted
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Throw the chip out.
Sorry.
Reversing the power supply on the micro is a fatal error.
JC
You melted the protection diodes, now they are a short, so the chip is unfortunately dead.
If you have anything else connected between Vcc and ground, they might also have failed.
If you have a tendency to have such errors, connect a big (current rated) diode across the power supply connections on the board in reverse. Maybe a 1N4001, etc. Anode to ground, cathode to positive. Yes, there will be a voltage when reverse connect, but often, it will often be low enough to avoid damage to some electrolytic caps and many semiconductor devices.
Jim
I noticed that ground and vcc pins of atmega32 chip are shorted.
Do you mean while reversed? Yes, that is true (makes a diode "short") ...if the current is kept low, things might survive.
If you mean I noticed that ground and vcc pins of atmega32 chip are shorted, after the proper polarity is applied, you'd better get out your credit card.
Don't hook up your wires while using a candle.
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The only AVR that gives any slack for stupidity is the ATmega48,88,...328 28pin DIP. If you plug it into a socket backwards, the reflective but reversed GND and VCC pins prevent it from being destroyed as described above.
ka7ehk wrote:
If you have a tendency to have such errors, connect a big (current rated) diode across the power supply connections on the board in reverse. Maybe a 1N4001, etc. Anode to ground, cathode to positive. Yes, there will be a voltage when reverse connect, but often, it will often be low enough to avoid damage to some electrolytic caps and many semiconductor devices.
I use this method in some of my designs.
except I think SCHOTTKY diode is better since forward voltage is lower.
with 1N4001 (forward voltage = 1V) the MCU may see -1V which crosses the lower limit of ablosute max rating of ATmega32 (-0.5V)
maybe 1N5817 (forward voltage = 0.45V) is better.
I also use 1N400n diodes, and if it don't blow a fuse somewhere before any damage you have a big problem with your power line !
yeah it is dangerous for high current power supplies. but the same risk is always exists with or without using reverse protection diode.
reverse diode method is good for low voltage 3V/5V and protected power supply with low current capacity.
problem is in high current there is voltage dropout over fuse, and not good idea for low voltages 3V/5V
if I accept voltage dropout then I simply use a diode in series to Vcc, it is more safe.
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