Hi everybody.
I'm developing a DMX512 receiver and have some doubts about grounding and transients protection.
This is the receiver scheme:
Input and output follow floating topology for DMX receivers.
Vx And Vcc are isolated supplies (each one with its trafo, rectifier, etc).
ADM4853 is a RS485 transceiver and 6N137 is an optocoupler.
D2, D3 and D4 are bidirectional transient supressor diodes.
All grounds in the system but XGND are tied to chassis ground.
For transient protection, I've followed this scheme:
It uses a grounded topology, with bus shield tied to system GND, wich is not recommended.
I don't know if I should tie TVS diodes to XGND (as shown in the first image) or should do to bus shield (pin 1).
For transient supression, it's also recommended add a filter at the single ended side of the receiver. I've used a RC filter like in the second image, but in my schematic, the capacitor (C32) is in the opposite side of the resistor (R57).
Should I change it?
Thanks
I'm developing a DMX512 receiver and have some doubts about grounding and transients protection.
This is the receiver scheme:
Input and output follow floating topology for DMX receivers.
Vx And Vcc are isolated supplies (each one with its trafo, rectifier, etc).
ADM4853 is a RS485 transceiver and 6N137 is an optocoupler.
D2, D3 and D4 are bidirectional transient supressor diodes.
All grounds in the system but XGND are tied to chassis ground.
For transient protection, I've followed this scheme:
It uses a grounded topology, with bus shield tied to system GND, wich is not recommended.
I don't know if I should tie TVS diodes to XGND (as shown in the first image) or should do to bus shield (pin 1).
For transient supression, it's also recommended add a filter at the single ended side of the receiver. I've used a RC filter like in the second image, but in my schematic, the capacitor (C32) is in the opposite side of the resistor (R57).
Should I change it?
Thanks
