SN65C1168: Data rate question

Vincent Chen64988

Part Number: SN65C1168
Other Parts Discussed in Thread: CD4097B,

Hi Team,

My customer has a application circuit as the attached diagram below, one TX/RX from MCU will be switched to one of the six channels RS-422 transceiver. So, customer choose CD4097B as a multiplexer. Since the supplied voltage of CD4097B is 5V, the on-state resistance could be up to 1.xK ohm and the RS-422 data rate is 400Kbps, customer wounder will the multiplexer affect the date transmission to cause data loss? Could team provide the equation to explain this circuit workable or not? The PCB distance between MCU and transceiver is 7cm, btw.

Thanks very much.

Vincent Chen

over 7 years ago

0 Cristian Soltero52 over 7 years ago

TI__Prodigy 240 points

Hello Vincent,

The possible 1 kOhm on resistance of the CD4097B part should not attenuate any input signal coming from the MCU as the input impedance of the driver for the SN65C1168 is already large in magnitude. Also, as long as the data rate is lower than approximately 3.2 Mbps due to the low pass filter created with the input resistance of the driver, then the input signal will not be adversely affected.

Best regards,
Cristian Soltero

0 Vincent Chen64988 over 7 years ago in reply to Cristian Soltero52

TI__Expert 4480 points

Hi Cristian,

Got it, thanks very much for the information.

Best Regards,
Vincent Chen

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SN65C1168: Data rate question