Overloading a circuit - Question

MisterBill2

Joined Jan 23, 2018
8,288
You can't make that statement unless you state the actual voltage, all of the conditions and also the duration of the voltage. A voltage of 5.001 exceeds 5.000 volts so will that matter? Actual testing of the type you are getting at is a complex lab environment type of test along with monitoring and recording everything happening. Starting with ambient temperature, ambient RH (Relative Humidity) thermal rise on the part under test until mean failure and the list goes on. Every parameter also needs well defined.

As was pointed out you want to create an Over Voltage Condition, that said you need to define all of your test conditions as well as your test methods and a detailed procedure. That done you need to lest all of your equipment requirements, that is the equipment you plan to use to conduct your test. What you are describing comes under destructive testing since you plan to destroy the part during the testing. You also need to describe in detail how you plan to acquire the data and where you plan to put the data during the test.

So what is your plan and exact goal, that means well defined. I want to apply a high voltage to a PIC Chip is not well defined.

Ron
Picky Picky, PICKY!!!
 

ebp

Joined Feb 8, 2018
2,332
Inputs can be protected against damage by use of series resistance to limit the current into built-in protection diodes to some reasonably small fraction of their rated absolute maximum current. This protection does not assure that operation will be correct and in the case of circuits which operate at very low current (such as a microcontroller in SLEEP mode with little other circuitry powered from the same supply rails) it can result in the supply rail being pushed above the allowable maximum voltage. Protecting an input, especially an analog input, from excessive voltage without interfering with normal operation can be moderately difficult and the methods used depend a great deal on the specific nature of the whole circuit. I have used an analog to digital converter where all channels were corrupted if the voltage on any channel exceeded the positive supply rail by more than a few tens of millivolts. Something like this is difficult to deal with. I am not aware of this being a problem with PICs, but I can't say for certain.

You will not get 40 volts back EMF, which is something very distinct from voltage due to inductor discharge, from a motor that runs at 24 volts unless the motor is being mechanically driven by something that causes the speed to be at least 40/24 of what it was when being driven by 24 volts. In terms of inductive discharge when the current is interrupted, the voltage can be "unlimited" but in practice is likely to be in the range of a few hundred volts at the most. The inductive discharge is readily handled by a freewheeling diode.
 
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