[RS485] Proudct selection advice needed

To whom may it concern,

Hi I'm HS.

I need to convert RS485 signals to UART and brief block diagram of application is below.

The reference voltage of UART2 is 1.8V and output voltage of RS485 device that i found is 3.3V, so level shifter(Voltage translator) is populated.

But i think the voltage translator is a waste.

So i'm wondering if ADI have RS485 device whose output voltage is 1.8V in order not to use this level shifter.

I would appreciate you recommend me one and how to convert the RS485 signals to UART.

Thank you and i hope you have a great day!

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  • 0
    •  Analog Employees 
    on Dec 17, 2020 1:18 PM 2 months ago

    Hello HS, 

    We have a few options available with a built in level shifter than operates down to 1.8V. 

    Your design looks to be full-duplex so I would recommend one of the following

    • ADM3064E (3.3V or 5V powered, enhanced ESD protection, for data rates up to 500kbps)
    • ADM3068E (3.3V or 5V powered, enhanced ESD protection, for data rates up to 50Mbps)
    • LTC2865 (3.3V or 5V powered, fault protected of 60V and enhanced common mode range)

    Regards,

    Neil 

  • Hi NQuinn, 

    Thank you for your recommendation!

    It's actually half duplex that signals flow from RJ45 through RS485 device to UART.

    So i would appreciate you recommend me half duplex one and expected power dissipation if it's available.

    Thank you!

  • +1
    •  Analog Employees 
    on Dec 18, 2020 4:11 AM 2 months ago in reply to feelyoursoul

    Hi HS, 

    In that case for half duplex networks I would recommend these: 

    • ADM3062E (3.3V or 5V powered, enhanced ESD protection, for data rates up to 500kbps)
    • ADM3066E (3.3V or 5V powered, enhanced ESD protection, for data rates up to 50Mbps)
    • ADM3095E (3.3V or 5V powered, with 42V fault protection and Level 4 ESD, EFT and Surge protection, data rate up to 2.5Mbps) 

    If you still would like to use the LTC2865 full duplex transceiver mentioned above, it can also be configured for half duplex operation, by connecting pin Y to pin A, and connecting pin Z to pin B.

    These products include details on the power consumption in the datasheets. The current consumption for the DC case is in the specification tables. Details on loaded power supply current across data rate and temperature are included in the typical performance curves section. 

    If you've any queries on the power consumption for a particular part which is not covered in the datasheet, please let me know, 

    Regards,

    Neil 

Reply
  • +1
    •  Analog Employees 
    on Dec 18, 2020 4:11 AM 2 months ago in reply to feelyoursoul

    Hi HS, 

    In that case for half duplex networks I would recommend these: 

    • ADM3062E (3.3V or 5V powered, enhanced ESD protection, for data rates up to 500kbps)
    • ADM3066E (3.3V or 5V powered, enhanced ESD protection, for data rates up to 50Mbps)
    • ADM3095E (3.3V or 5V powered, with 42V fault protection and Level 4 ESD, EFT and Surge protection, data rate up to 2.5Mbps) 

    If you still would like to use the LTC2865 full duplex transceiver mentioned above, it can also be configured for half duplex operation, by connecting pin Y to pin A, and connecting pin Z to pin B.

    These products include details on the power consumption in the datasheets. The current consumption for the DC case is in the specification tables. Details on loaded power supply current across data rate and temperature are included in the typical performance curves section. 

    If you've any queries on the power consumption for a particular part which is not covered in the datasheet, please let me know, 

    Regards,

    Neil 

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