The modular approach has worked well for me, and I agree with all your reasons for using it.
I suspect an ESD event is causing the damage; we just need to find out where it's coming from and mitigate it. The first place to look is power supplies. In order to minimize the impact of an ESD event, all of the connections on the power supply need to be at the same potential when the power-supply is connected to your board. Also, all of the power connections on the board need to be at the same potential before you connect the supply. This is easily done with large resistors between each power-supply voltage, and your circuit ground; typically I use 1-10Megs for higher voltages like the anode supply. For lower voltages, 10-100K is fine. These resistors eventually discharge any power-supply capacitors; you can calculate the time constant T=5*R*C, where T is seconds, R is ohms, C is farads. The smaller R is, the shorter the time is to discharge, but also there is more wasted power. If you have multiple boards, etc, each one needs it's own set of bleeder resistors. I dont have the time to go into all of the nuances about ESD design practices here, but if you have all supplies tied together, most of the other components will protect eachother thru conductive paths; this is especially true for MOS IC's because they have built-in ESD protection circuitry that essentially ties all pins together. Even though a discrete MOS device is unlikely to have ESD protection built-in, if it's connected to another device, such as a microcontroller, that has ESD-protection, both will be protected in-circuit. If you really want to be as careful as possible, touch the ground of the power supply with one finger, and the ground of the board with another finger before connecting the power cable. This will equalize the 2 components to the same voltage thru your body resistance within milliseconds. When you connect them, there is NO ESD event. Finally, make sure you are connecting power-supplies first, then signal connectors. That way, there will not be an ESD event when the signal connector is inserted because the power cable has already equalized the 2 devices. Be careful, though, because signal connectors that tie grounds together can create ground loops in your system. If you have noise-sensitive circuits, like clock signals, you may need to use differential signalling, schmitt-triggers, or opto-isolators. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/273afd8d-7d87-4cd9-81e8-b680fe7dc31f%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
