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ADIN1100 Transmit Voltage Configuration

We are using the ADIN1100 in an application that must meet Ex ia hazardous locations standards. A question has come up about the 1.0 Vp-p transmit magnitude of the T1L signal coming out of the spur power source ports on our product.

We have pin 31 (RXD_0/nTS2P4_EN) pulled high through a resistor to force the spur PHYs into 1.0 Vp-p mode. I am looking at the datasheet and it says on Page 25 that pulling pin 31 high disables 2.4 Vp-p mode. It also says in a couple places "1.0 V p-p transmit level operation is required for intrinsically safe operation".

Is there any way for software configuration of the PHY through the MDIO interface to override the configuration value of the resistor and allow the PHY to be put into 2.4 Vp-p mode? I understand that puling pin 31 high will disable advertising of 2.4Vp-p mode for auto negotiation purposes, but would it be possible to disable auto negotiation and force B10L_TX_LVL_HI to '1' and enable 2.4 Vp-p mode?

This is critical because it will impact the Uo entity parameter for the spur ports.

Thanks,

Tony

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  • Hi Tony,

    The current recommendation is to use Auto-Negotiation.

    Can you please give us more information about your application so we can help you better? Intrinsic safety applications require a 1.0 Vpp transmission mode in the spurs. What is the reason you need to be able to enable 2.4 V p-p?

    Regards,

    Raquel

  • Hi Raquel,

    Thanks for your reply.

    In normal operation we would expect our customers to us auto-negotiation. Our application is an APL field switch. My question is specifically about the spur PHYs which will be able to extend to IEC Ex Zone 0.

    My question is more about what is possible. We are being asked by the team assessing our switch if there is any circumstance where the PHY could transmit in 2.4 Vp-p mode even though pin 31 is pulled up externally.

    We wouldn't want to transmit in 2.4 Vp-p mode on our spurs, but from a safety standpoint we need to understand if it is possible for a spur PHY configured with hardware to only operate in 1.0 Vp-p mode (pin 31 pulled up) to transmit in 2.4 Vp-p mode if auto-negotiation is disabled and the MDIO interface configured the registers properly to allow 2.4 Vp-p operation.

    Or would pulling pin 31 high disregard or not allow the registers to be configured for 2.4 Vp-p operation?

    Thanks,

    Tony

  • Hi Tony,

    Thanks for your explanation. If pin 31 is pulled high, it is not possible to configure the part to transmit in 2.4 Vp-p even if Auto-Negotiation is disabled and you try to force it via software.

    I hope this answers your query.

    Regards,

    Raquel.

  • Raquel,

    Thank you for the confirmation.

    Tony

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