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Original question:

ISOW1412: Low EMI layout question

ISOW1412: EN/FLT pin

Youhei Miyaoka
Expert 3975 points
Part Number: ISOW1412

Tool/software:

Hello team,

Can you support my customer's question as shown in below?

1. EN/FLT pin: Can this port use as EN or FLT? Cannot use as EN and FLT.

2. Is this 11.2 figure shows example use as FLT?

3. If they use as EN, they need to set extra GPIO from MCU side, is this correct?

4. Can they use as VDD=3.3V sharing with VIO?

5. I heard that the RS485 bus-side current exceeds 20mA. Is there any problem if an extra 20mA be inputed to the VISOIN? 

6. If the EN/FLT port is not used as EN or FLT, what should the port handle?

Regards,

Youhei MIYAOKA

  • 0
    TI__Expert 7465 points

    Hi Youhei,

    For EN/FLT pin details please read through the datasheet section 10.6.2, and how it can be used as both at the same time:

    Question 4: See Pin Description

    Youhei Miyaoka said:
    5. I heard that the RS485 bus-side current exceeds 20mA. Is there any problem if an extra 20mA be inputed to the VISOIN? 

    20mA mentioned in datasheet is the additional load current available from VISOSUT for external load other than VISOSIN current which goes for RS485 functionality.

    Youhei Miyaoka said:
    6. If the EN/FLT port is not used as EN or FLT, what should the port handle?

    . If EN is floating, DC-DC converter is enabled through internal pull up resistors. .

    Regards
    Varun