Is it me, or the AWG output protection diode D5 placement was a VERY bad idea?
External peaks will go right away into the +-5V analog voltage without any limitation, potentially killing a lot of stuff.
The diode and/or traces/pcb will burn in no time, and if the diode opens the voltage will reach the amplifier anyways.
I'm confused. There are resistors totaling 50 ohms in either path. That's 100 mA if you apply 10V when using the AWG. If using the external trigger, it's 100 mA at 8.3V.
Such stupid design. Should be placed at the pin 6 of the amplifier, so R9, R11, R143 limit the current, yet protecting the amp.
In the worst case, the damage will be just a burnt resistor.
Am I looking at a modified schematic? What you think it should be? If so, I agree.
Although, I have done exactly this on designs before. If there is no option for series resistance, this is still an effective way to deal with static.
Hmmm, you are making me rethink this. The design I'm referring to runs the signals through an analog switch for isolation. The diodes are to ±12V on the connector side. The 12V supply is on the motherboard and is supplying 8 of these circuits plus the motherboard circuitry. The -12V is very light. The idea of sinking the excess voltage into the supply, is that the normal supply current is greater than the surge current. The -12V rail likely has almost no current. So that's not good. I thought the switches were ESD protected internally, but I only find this for one of the part numbers used. I guess that's why I added the diodes.
This is to a connector used for serial ports of different standards (RS-232, 422, 449, etc), and audio. Not likely to be driven by anything beyond ±12V other than static. Are networking equipment rooms anti-static protected?
I'm redesigning this card to replace EOL components. I will need to take better notes this time. They've asked me to use parts that are expected to be in production for 10 years. Not sure how that's going to happen. They have a service that evaluates parts for them. It will be interesting to see what they come up with.