I'm building a DMX transmitter, and follow the Texas Instruments guideline on IEC ESD, EFT, and surge resistant RS-485 circuits, having the following configuration at the moment:

The MOVs clamp the ESD voltage to around 1kV, the TBUs block the ESD current to 1mA and the diodes clamp the voltage to 15-20V. That is higher than the maximum bus voltage, so the differential driver has to deal with the excess, which isn't a problem in transients but can lead to damage in case of surges, so two 10 Ohm MELF resistors limit the surge current. That is the reason for them.

Now, my problem is where to place the 120 Ohm termination resistor on the transmitting end of the DMX bus? Infront of the MELF resistors or behind, or even before the MOVs?

Or should I just take a 100 Ohm resistor and put it with the 10 Ohm resistors in series so resistance is 120 Ohms? In the later case before or after the MELF resistors, which is best for avoiding signal reflection?

I'm very lost currently, help is much appreciated, thanks ;)

I'm building a DMX transmitter, and follow the Texas Instruments guideline on IEC ESD, EFT, and surge resistant RS-485 circuits, having the following configuration at the moment:

The MOVs clamp the ESD voltage to around 1kV, the TBUs block the ESD current to 1mA and the diodes clamp the voltage to 15-20V. That is higher than the maximum bus voltage, so the differential driver has to deal with the excess, which isn't a problem in transients but can lead to damage in case of surges, so two 10 Ohm MELF resistors limit the surge current. That is the reason for them.

Now, my problem is where to place the 120 Ohm termination resistor on the transmitting end of the DMX bus? Infront of the MELF resistors or behind, or even before the MOVs?

Or should I just take a 100 ohm resistor and put it with the 10 Ohm resistors in series so resistance is 120 ohms? In the later case before or after the MELF resistors, which is best for avoiding signal reflection?

I'm very lost currently, help is much appreciated, thanks ;)