ISO1452: ISO1452 Y AND Z OUTPUTS FULL DUPLEX MODE

Jason Markham

Part Number: ISO1452
Other Parts Discussed in Thread: ISO1450, ISOW1432

Tool/software:

I am looking to use the iso1452 device to isolate the microcontroller from the external rs485 bus. i am confused if i should use only the a and b output with a 120 ohm terminator resistor and an sm712 protection diode to the rs485 device. Do i need to wire also the y and z outputs ?

thanks

Jason

2 months ago

0 Varun Kumar 2 months ago

TI__Expert 7175 points

Hi Jason,

Thanks for reaching out. Please find my inputs below:

Jason Markham said:
Do i need to wire also the y and z outputs ?

Well looks like you want a Half-Duplex Operation. If So then you need to short Y/Z to A/B. Refer this FAQ for more details: https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/1314992/faq-iso1452-faq-how-to-configure-a-rs485-full-duplex-transceiver-as-half-duplex

Regards
Varun

0 Jason Markham 2 months ago in reply to Varun Kumar

Prodigy 10 points

thanks for replying , no i am interfacing with a abb vfd and i need bi directional traffic - full duplex as i will be sending commands to operate it and reading back values to process them.

i take it i should leave y and z unconnected ?

Also i am concerned about power consumption of the isolator as i have only 200ma available from the supply rack i am taking power from. Will the dc to dc converter suffice this power requirement ?

0 Andrew J 2 months ago in reply to Jason Markham

TI__Mastermind 28405 points

Hello Jason,

Y and Z are the transmitter pair of the ISO1452 and are needed for the device to transmit any data. If you would like to transmit and receive over the same differential pair, then Y/Z needs to be connected to A/B as a half-duplex (shown in the FAQ). ISO1450 is already configured as a half-duplex transceiver.

ISOW1432 has the integrated DCDC converter which should consume less than 200mA according to the datasheet.

Best,
Andrew

Isolation

Isolation forum

ISO1452: ISO1452 Y AND Z OUTPUTS FULL DUPLEX MODE