ISO1176T: Isolated RS485

Ray Vincent Aranzaso

Mastermind 18180 points

Part Number: ISO1176T
Other Parts Discussed in Thread: ISO1410, SN6501, SN6507

Hi,

Good Day.

I am designing Isolated RS485 circuit for 8 sensors. Following are the requirements

1) Output voltage for RS485 transceiver (isolated side) and for sensor loads: 5V

2) Output current for RS485 transceiver (isolated side) and for sensor loads: 150mA + 100mA for eight sensors

3) Output power switching control

4) Data rate for half-duplex, isolated RS485 transceiver: 19.2kbaud

5) Logic IO voltage (CPU side of RS485 transceiver) is all 3.3V LVTTL

6) Consider EMI / ESD

7) Consider switchable termination (desired but not must)

8) Input voltage range: Either 4.6VDC or 6.5VDC

9) Consider pin reversal capability for RS485 transceiver (A/B) pins (desired but not must)

Could you please suggest integrated solutions such as ISO1176T or other solutions such as ISO1410 with external isolated DC-DC converter ?

Please advise. Thank you very much.

Best Regards,

Ray Vincent

over 2 years ago

0 Vikas Jeevannavar over 2 years ago

TI__Expert 3136 points

Hi Ray Vincent Aranzaso,

Thanks for providing the elaborated requirements. I would suggest you use our newer devices which are better in performance. I would suggest you use ISO1410 and our transformer driver SN6501 or SN6505 will cover the requirements mentioned above. We don't support switchable termination or pin reversal on ISO1410.

Please go through the following app noted for more information.

Please let us know if you have further questions.

Thanks

Vikas J

0 Ray Vincent Aranzaso over 2 years ago in reply to Vikas Jeevannavar

TI__Mastermind 18180 points

Hi Vikas,

Good Day. Please see below the response of our customer to your reply. Thank you very much.

The input voltage available for power supply is 6.5VDC. Could you please recommend other solution for isolated power supply used in RS485?
SN6501/SN6505 only accepts 3 to 5.5 VDC therefore, I believe these cannot be used in my case.

Best Regards,

Ray Vincent

0 Vikas Jeevannavar over 2 years ago in reply to Ray Vincent Aranzaso

TI__Expert 3136 points

Hi Ray,

SN6507 has wide input voltage range upto 36V. The customer can use this to power with 6.5VDC. Hence, ISO1410 with SN6507 can be used for the application. Please note that ISO1410 can support only upto 5.5VDC on either sides.

Thanks
Vikas J

0 Ray Vincent Aranzaso over 2 years ago in reply to Vikas Jeevannavar

TI__Mastermind 18180 points

Hi Vikas,

Good Day. Please see the latest response from our customer. Thank you very much.

I have gone through the datasheet of SN6507 but facing some issues in selecting external components (transformer, LDO) for fixed 6.5 VDC input and 5 VDC output. Could you please help in recommending part numbers for these external components?

Best Regards,

Ray Vincent

0 Vikas Jeevannavar over 2 years ago in reply to Ray Vincent Aranzaso

TI__Expert 3136 points

Hi Ray,

Please give me another day to have a look at this and get back to you.

Thanks

Vikas J

0 Vikas Jeevannavar over 2 years ago in reply to Ray Vincent Aranzaso

TI__Expert 3136 points

Hi Ray,

We don't have any reference design for the voltages mentioned above. The customer can go through "8 Detailed Description" and "9 Application and Implementation" which elaborates steps to be followed & equations to calculate the specs of the transformer, LDO and other components.

SN6507DGQEVM user guide also has the schematic and BOM for reference to design for 6.5VDC input and 5VDC output.

Thanks
Vikas J

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ISO1176T: Isolated RS485