ISO1432: Power supply voltage of RS-422 transceiver IC on communication partner

MESH

Part Number: ISO1432
Other Parts Discussed in Thread: SN65HVD1792

Hello

I am designing RS-422 interface circuit using ISO1432.
(3.3V power is supplied to the VCC2 pin on ISO1432)

5V power is supplied to the RS-422 transceiver IC, which is the component of the communication partner.

The supply voltage is different from the component of the communication partner, but let me check that there is no problem.
(It is within the range of VID (-15V to +15V) and VI (-7V to +12V) described in the ISO1432 data sheet and I think that there is no problem, but please check it just in case)

Regards,
MESH

over 2 years ago

+1 Koteshwar Rao over 2 years ago

TI__Mastermind 49445 points

Hi MESH,

The RS-422 interface is a differential interface, hence, it allows interfacing of nodes with 3.3V and 5V power supplies without any issues. The two nodes should be able to communicate without any issues. Thanks.

Regards,
Koteshwar Rao

0 MESH over 2 years ago in reply to Koteshwar Rao

Intellectual 830 points

Hi Koteshwar,

Thank you for your reply.

In addition, please confirm that there is no problem with the difference in supply voltage for the built-in failsafe circuit of ISO1432 and the

failsafe function of SN65HVD1792 to be used by the communication partner.

Regards,

MESH

+1 Koteshwar Rao over 2 years ago in reply to MESH

TI__Mastermind 49445 points

Hi MESH,

Yes, the bus pins and associated circuit are rated for >>5V while the internal failsafe biasing pins would be by 3.3V or 5V power. Hence, this shouldn't be an issue either. Thanks.

Regards,
Koteshwar Rao

0 Koteshwar Rao over 2 years ago in reply to Koteshwar Rao

TI__Mastermind 49445 points

Hi MESH,

I am sharing below a link to another E2E post that discusses in detail the RS-485 compatibility between 3.3V and 5V supply devices. This is applicable to RS-422 as well.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/93260/rs-485-compatibility-between-3-3v-supply-and-5v-supply-devices

Regards,
Koteshwar Rao

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ISO1432: Power supply voltage of RS-422 transceiver IC on communication partner