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First of all thanks for reading this post. I am designing an isolated board for several peripherals for which I need your help/suggestions. The board contains a buck converter (like LM2596) to step the input voltage from (9-36V) to 5 V. Then there is an isolation converter ( Vin=5V, Vo=5V isolated). My first questions is regarding this isolation converter. The only component I could find online is 0505 series (0505 converter) which is limited to 1 W only. I need at least 1.2 Amps of current supply. The peripherals include one isolated RS485 transceiver, one CAN bus transceiver and two or three ADC connected via I2C bus with a digital isolator between ADC and microcontroller. Following are my questions regarding this board and I would really appreciate your help.

Is there any similar model like 0505 converter(isolated) with higher power handling capacity?

Is the board design ok? with respect to isolation!

The microcontroller runs on 3.3 V so I would need to use a 5 to 3.3 V linear regulator, would that effect the performance too much? is so should i go for 5 to 3.3 V isolated converter?

Any other suggestions regarding this design?

Here is the picture of this board.

enter image description here

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  • \$\begingroup\$ Product reccomendations are off topic for this site. That being said there are many distributors with DC DC isolators with the specs you want \$\endgroup\$
    – Voltage Spike
    Commented Apr 8, 2021 at 21:23

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Circuit seems ok regarding isolation. you should also take care when designing the PCB and keep enough distance between the isolated side and the uC side. Also do not mix traces from the isolated side with traces from the uC side. Doing board cut outs under the isolation ICs and the isolated supply is also recommended.

Also consider the rating of Isolation of your converter and isolation ICs. Normally they are rated for 1 second and your should convert to continuos operation. See the following calculator.

https://recom-power.com/en/support/tools/isolation-calculator/isolation-calculator.html?0

Regarding isolated DC DC converters you have many options with more than 1W power. See following link

https://www.digikey.com/en/products/filter/dc-dc-converters/922?s=N4IgjCBcoKwOwGYqgMZQGYEMA2BnApgDQgD2UA2iAEwAsAnGHBMVQmFTDCCwggAwAOAGzdqvAXT6iqQuDRhUQAXWIAHAC5QQAZXUAnAJYA7AOYgAvsTA0myEGkhY8RUhWqCFNaYLhCpLPjoEAThvBkFpMD4qKjowgQlIwTABSOshJBZ6RggVEA0tXUNTCysFLmh7DBwCYjJISloghmls2yy6BVCOmhpUjph6aSEYfzE%2BPhTpfjAYETyCyB19YzNLahTQyocnWtcG8AACAHVRMAA6DhOz85hrq3OBe%2BpnhGeaZ7vT4iFrhc0lgBVIwGdQAeXQAFl8JhcABXPT4UrUKhgCDbarOOpuXJqAEgACSRnU%2BBM%2BD0FnWigOABMUIc6YcUCQjAA3ckkilKcxAA

You also need to isolate your CAN and RS485 signals. I'm used to working with SPI and I2C signal isolators but just google RS485 isolator or CAN isolator and you will find many options.

For I2C isolator I have used Si8602AC

For the CAN isolation you have for example ADM3053

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  • \$\begingroup\$ You also need to isolate the signals to the rs485 and CAN transceivers. \$\endgroup\$
    – Kartman
    Commented Apr 8, 2021 at 12:26
  • \$\begingroup\$ the transceivers are isolated with respect to power. Do i need to do signal isolation as well? I think a simple digital isolator will work for that! \$\endgroup\$ Commented Apr 8, 2021 at 14:35
  • \$\begingroup\$ You definitely also need a signal isolator. I thought those boxes you had represented the signal isolators. Added some options to my answer \$\endgroup\$
    – SolarTec
    Commented Apr 8, 2021 at 21:15

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