ISO1500: How can I use this device for an inline RS-485 isolation buffer

Adam Torma

Mastermind 45710 points

Part Number: ISO1500

Tool/software:

e2e,

I'm working on a in line RS-485 isolator project with the below requirements:

Inputs:

V+ 24Vdc/4A – (Class 2 power supply)
- GND
RS485 – A
RS485 – B

Outputs (isolated):

V+ 18 Vdc/250mA – (24 Vdc/250mA would be better)
- GND
RS485 – A
RS485 – B

I was looking into the ISO1500 as a recommendation for this as the ISOW14xx devices wouldn’t have enough output power for this application. Is the ISO1500 what you would recommend for this?

Please let me know if you have any questions or need any more information.

Adam

10 months ago

0 Clemens Ladisch 10 months ago

Guru 322010 points

The ISO1500 can work as a component in such a design. (You still need the isolated power supply and the logic handling the bidirectional communication.)

0 Andrew J 10 months ago in reply to Clemens Ladisch

TI__Mastermind 34555 points

Hello Adam,

What Clemens said is correct. To add a little more detail, see below:

Based on your description you may be looking for a repeater or buffer application for your bus. The Data-rate independent half-duplex repeater design for RS-485 (Rev. A) app note goes into details about the additional circuitry needed to accomplish this. In the app note two ISO1500s are used. You can also use ISO1500 with non-isolated transceiver to simplify the design a little.

Best,
Andrew

Isolation

Isolation forum

ISO1500: How can I use this device for an inline RS-485 isolation buffer