SN65LVDS22: Dc Bias without AC coupling

Dan Abbey

Part Number: SN65LVDS22

Hi Team,

Is it possible to DC Bias without AC coupling on an LVDS line, something like fig 3 but without the capacitors? Not sure if this could cause damage to the device driver?

Use case is SN65LVDS22 (3.3V) paired with an FPGA (2.5V) with the DC bias powered from the 2.5V. AC coupling is not an option in the application but the customer would like the additional protection DC biasing offers.

Thanks and best regards,

Dan

over 4 years ago

0 Ikechukwu Anyiam over 4 years ago

TI__Mastermind 35130 points

Hi Dan,

Yes, but a step-up resistor network like the one shown in Figure 5 here would be needed: https://m.eet.com/media/1135468/330072.pdf as well as solving a system of equations for the resistor values to get the desired DC bias, swing, and 100-ohm equivalent impedance. It would be much simpler to AC couple the connection.

Regards,

I.K.

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SN65LVDS22: Dc Bias without AC coupling