SN65LBC176-Q1: Schematic Review

Hi Kevin,

The series resistors on the bus appear to be quite large. The purpose of these resistors is generally to improve transient immunity or open-circuit failsafe biasing and are typically low resistance values to reduce the signal attenuation as they are in series with the driver circuitry. Larger values are used in systems where the receiver and driver pins are seperate (full-duplex devices). I would recommend using smaller resistor values here (maybe around 10-ohms) to reduce the signal attenuation through this circuitry. I'd also like to recommend the following App Note which describes the process of calculating fail-safe resistor values:

RS-485: Passive failsafe for an idle bus

This transceiver is compatible with 3.3V logic input so it should be able to be driven by a 3.3V MCU. The device will drive 5V output logic so be sure that the MCU can withstand this higher input voltage. 

Let me know if you have any more questions or if you have any particular concerns regarding the schematic.

Regards,
Eric