Team,
Can you please help with SN75179B questions from my customer:
We are developing a prototype for a new device. The device includes 3 absolute encoders which output a RS-422 differential signal. We selected the SN75179B differential driver to interface between the encoder and the microcontroller.
One of my concerns is that it appears the SN75179B responds to inputs that straddle 0 volts (see table below from data sheet) whereas our encoder’s output signal is consistently 0 (low) to 5 volts (high).
The “high” and “low” signals output from the SN75179B are on the range of around -400 mV to 400 mV (see attached photo)– which can’t be interpreted immediately by the microcontroller and would require additional circuitry to rectify, in which case it would probably be easier to not use the SN75179B.
Here is a pic of the local schematic. Data 1 and CLK 1 go to the microcontroller.
In summary, I would like to verify the function of the SN75179B when the differential input is 0 Volts and overall, make sure that this component is appropriate for this application. And if it is appropriate, if there is additional necessary circuitry outside of the driver.
Thanks
Viktorija
SN75179B
