WCLK output circuit

[mattd]

We duplicated the WCLK output design from the EVM and noticed that the output level, unterminated, is around 2.5V due to the 75 ohm and 220 ohm voltage divider. When terminated with 75 ohms, the WCLK output is around 1.4V. Some devices that we've tested with require a 4V signal going into their WCLK input to sync, I'm guessing because they have 5V CMOS logic on their WCLK inputs instead of TTL, or instead of using a differential input. Is this a known issue with the EVM, or is the design assuming that WCLK inputs on other products will have TTL or differential inputs? Is there a recommended change? We're probably going to change the RS-485 transceiver to a 5V part and change the 75 ohm output resistor to something smaller, like 10 ohms.