Hi guys,
I have built a project where I have a teensie 3.2 measuring 2 thermistors, totaling interrupts from a hall effect sensor (measuring a flow meter), and then sends the 2 temps and total counts from the flowmeter over canbus using a TI CAN transceiver.
I included a picture of my setup, the can transceiver is on the bottom of the board otherwise you can see everything.
For power I only have 12VDC available so I am using a 3.3V linear regulator. The whole thing is potted in DP-270 3M Scotch Weld Potting epoxy. I've built 4 of these and they have been running pretty much constantly on my car for several months. Yesterday I had one die on me. By die I mean I stopped receiving data over CAN and error frames existed on the bus. I investigated a little and noticed that if I removed the power and waited a few seconds/minutes and plugged the power back in the teensie would power up and start sending data again for a variable amount of time. It seemed the longer I kept it unplugged, the longer it would stay powered up and send CAN data.
I think I may have gotten the teensie too hot. I don't know the exact temperature the teensie was running at but the fluid being measured by this exact flowmeter was hotter than its ever been (but other 3 not as hot) due to high ambient temperatures (Fluid was 65C) and the whole block of potting compound containing my circuit is potted directly to the brass flowmeter. Additionally the linear regulator is inside the potting compound as well (and it gets really hot...bad design element there I know, plan to use a switching regulator on my next version).
At any rate, between the block of potting compound being heated up to 65C from the fluid and the linear regulator being an additional heat source right next to the teensie in the potting compound I think I might have exceeded the maximum temperature of the teensie...which from searching the forums I believe to be 85C...is that correct?
I replaced the whole power input side of the circuit (regulator and capacitors) by grinding away the potting material and get the same behavior with those components replaced.
MY question is, does this behavior of powering on for a short period and then turning off line up with what might happen if the teensie were heat damaged?
I have built a project where I have a teensie 3.2 measuring 2 thermistors, totaling interrupts from a hall effect sensor (measuring a flow meter), and then sends the 2 temps and total counts from the flowmeter over canbus using a TI CAN transceiver.
I included a picture of my setup, the can transceiver is on the bottom of the board otherwise you can see everything.
For power I only have 12VDC available so I am using a 3.3V linear regulator. The whole thing is potted in DP-270 3M Scotch Weld Potting epoxy. I've built 4 of these and they have been running pretty much constantly on my car for several months. Yesterday I had one die on me. By die I mean I stopped receiving data over CAN and error frames existed on the bus. I investigated a little and noticed that if I removed the power and waited a few seconds/minutes and plugged the power back in the teensie would power up and start sending data again for a variable amount of time. It seemed the longer I kept it unplugged, the longer it would stay powered up and send CAN data.
I think I may have gotten the teensie too hot. I don't know the exact temperature the teensie was running at but the fluid being measured by this exact flowmeter was hotter than its ever been (but other 3 not as hot) due to high ambient temperatures (Fluid was 65C) and the whole block of potting compound containing my circuit is potted directly to the brass flowmeter. Additionally the linear regulator is inside the potting compound as well (and it gets really hot...bad design element there I know, plan to use a switching regulator on my next version).
At any rate, between the block of potting compound being heated up to 65C from the fluid and the linear regulator being an additional heat source right next to the teensie in the potting compound I think I might have exceeded the maximum temperature of the teensie...which from searching the forums I believe to be 85C...is that correct?
I replaced the whole power input side of the circuit (regulator and capacitors) by grinding away the potting material and get the same behavior with those components replaced.
MY question is, does this behavior of powering on for a short period and then turning off line up with what might happen if the teensie were heat damaged?