SN65HVD3088E: Common mode rejection capability of SN75176 and SN65HVD3088

Hi Walsh,

Common mode tolerance is typically specified for RS-485 transceivers in DC terms in alignment with the TIA/EIA-485 standard, which requires standard transceivers to support a common-mode bus voltage range from -7 V to +12 V. Both the SN75176 and SN65HVD3088E meet this requirement. There may be some variation from part number to part number when it comes to tolerance to AC common-mode deviation, but in general this is unfortunately something that is not fully characterized due to lack of a standard methodology.

If common-mode noise immunity is a key concern for your application, though, I would suggest looking into the newer THVD1550 device. This device was designed to have increased common-mode rejection in order to better operate without data loss in extremely noisy environments. This is reflected to some extent in the IEC 61000-4-4 electrical fast transient (EFT) immunity specification of that particular device. If you are not familiar with EFT, you can read more about it here: e2e.ti.com/.../what-is-an-eft.

Regards,
Max