Attiny1606 burning out when connected to a drv8251

Thread Starter

lavamanczgames

Joined Jun 25, 2023
6
Hi, I am designing my own locomotive DCC decoder, no need to know what that is. The major problem i am having now is that if i try to use the drv8251 the attiny1606 overheats and then burns out. Even when there is nothing connected to the output, i was just measuring the output voltage with a multimeter. Initially, everything was fine, but then, as i said, the mcu burnt out. The drv is using the reference voltage of the attiny, plus those resistors on the inputs should prevent possible overcurrent. Prior to assembling the whole PCB, I tested all the parts individually. First the voltage regulator, then separating the signal. And last i tested the drv. For the test, i used the same schematic for the drv as shown in the picture before, but instead of the attiny I was controlling it with arduino nano (vcc 5v). That seemed to work with no problem
EasyEDA(Standard) - A Simple and Powerful Electronic Circuit Design Tool - Google Chrome 20.04...png
 

simozz

Joined Jul 23, 2017
128
Hi,

Is PA2 connected as input or as output ?
In the latter case, you have no overcurrent protection, so if you accidentally have configured as output, having VOH with Q1 ON, it is a short to GND.
 
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Thread Starter

lavamanczgames

Joined Jun 25, 2023
6
After some iterations, the attiny completely stopped overheating and the circuit is working fine. But for one fatal exception, the attiny doesn't seem to be able to switch the B input of the drv high. Not sure why tho. All i have done was, directly connect ground to the drv and add 1k ohm resistors between the attiny and input of the drv. One of the inputs can be controlled fully, but the other (input B) cannot be controlled at all and is constantly pulled down, probably by the integrated pulldown resistors of the drv.
 
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