Hi,
I am using "SN65HVD09" as RS 422 receiver. But I am not using few channels. Should I keep it as floating ? or any other recommendation is there ?
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Hi,
I am using "SN65HVD09" as RS 422 receiver. But I am not using few channels. Should I keep it as floating ? or any other recommendation is there ?
Hi Brijesh,
If you take a look at the ELECTRICAL CHARACTERISTICS at page 5 you'll find the differential input thresholds voltages VIT+ and VIT-. Voltages from -200 mV to +200 mV at the differential input are not defined and the result could be an undefined or toggling output signal.
conclusion: If you use the device as a receiver and leave the differential inputs floating, the respective output A signal is undefined or maybe toggling. In order to obtain a stable condition, connect unused B+ with pull up resistor to Vcc and the B- to respective GND. Since the SN65HVD09 is positive logic your output signal will be a defined HIGH.
Let me know if this is helping you out.
Kind regards
Dierk
Hi Clemens,
thanks for pointing this out.
You are correct a 10 kΩ resistor is suitable. It is resulting in 0.5 mA current which is in the range of II Bus input current also shown in the ELECTRICAL CHARACTERISTICS at page 5 of the datasheet.
Kind regards
Dierk