Hi team,
I received the following question:
Our design uses the DS25BR150TSD re-driver chip from TI. The input signals are AC-coupled across a 150pF isolation capacitor. The differential signals output from the re-driver are again ac-coupled into an FPGA.
We’re experiencing many bit errors when the electronics are powered by a non-earth-grounded power supply. The input signals have an amplitude of ~200mV. When we add a pull up resistor to the IN+ signal of the re-driver and pull down resistor to the IN- signal, the bit errors are reduced. The higher the resistor value, the fewer errors. (We’ve tried resistor values between 2k-20k ohm). Can you explain what might be going on and why the pull-up/pull-down resistors impact the stability of the bit transmission?
Can you also explain the common mode voltage range specification listed in the datasheet under DC Electrical Characteristics?
thanks in advance,
Jens
