Hello,
I have made a simple small circuit for my company. It is used to measure and report whether or not a batteries terminal voltage is within a nominal range. I have 20 boards connected to a battery stack in house here. The circuit seems to run fine, but after a few days, the boards starts to fail --kinda--. The failure is intermittent and many times only manifests itself when attached to a battery. It's difficult to observe the problem on the bench. The problems take the form of timing and logic error from the CMOS digital ICs. I don't have problems with the optocouplers or comparators. The CD4049UB(inverter) is the worst. It seems to fail most frequently.
What could be the problem? The battery stack is connected to a battery charger. All the batteries are in series. The batteries are 12.5V each. Is it just bad practice to attach CMOS to a battery stack where the VDD, VSS with respect to earth ground can be as high as 600V?
I along with my colleges are baffled. The boss says the problem is that all the boards are in series along with the batteries. I asked him to elaborate more, but he couldn't. Whatever he thinks is the problem, he thinks doesn't require more explanation.
The board schematic is attached, and layout. Is it possible that a batch of board can just be flakey?
I have made a simple small circuit for my company. It is used to measure and report whether or not a batteries terminal voltage is within a nominal range. I have 20 boards connected to a battery stack in house here. The circuit seems to run fine, but after a few days, the boards starts to fail --kinda--. The failure is intermittent and many times only manifests itself when attached to a battery. It's difficult to observe the problem on the bench. The problems take the form of timing and logic error from the CMOS digital ICs. I don't have problems with the optocouplers or comparators. The CD4049UB(inverter) is the worst. It seems to fail most frequently.
What could be the problem? The battery stack is connected to a battery charger. All the batteries are in series. The batteries are 12.5V each. Is it just bad practice to attach CMOS to a battery stack where the VDD, VSS with respect to earth ground can be as high as 600V?
I along with my colleges are baffled. The boss says the problem is that all the boards are in series along with the batteries. I asked him to elaborate more, but he couldn't. Whatever he thinks is the problem, he thinks doesn't require more explanation.
The board schematic is attached, and layout. Is it possible that a batch of board can just be flakey?
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