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ISOW7843: pin treatment to use common layout for ISOW7843 and ISOW7821

Part Number: ISOW7843
Other Parts Discussed in Thread: ISOW7821, , ISOW7741

Hello Support team,

My customer is investigating common layout for ISOW7843 and ISOW7821. Package would be same and most pin assignment except next pins are same. Could you tell me pin treatment for next pins?

PIN # ISOW7821 ISOW7843 Question for pin treatment
5 NC OUTC Can set OPEN
6 NC OUTD Can set OPEN
7 EN1 NC Can NC pin(ISOW7843) be applied High or Low externally?
10 NC SEL Can NC pin(ISOW7821) be applied High or Low externally?
11 SEL IND Can IND(ISOW7843) be set open? 
12 NC INC Can INC(ISOW7843) be set open? If not, can NC pin(ISOW7821) be applied High or Low externally?

Thanks,

Koji Ikeda

  • Hi Ikeda-san:

    Thanks for posting your question on E2E!

    NC pins don't have any electrical connection, so they could be left floating or connected to HIGH/LOW externally. Please see below for my recommendations.

    PIN # ISOW7821 ISOW7843 Question for pin treatment TI Recommendation
    5 NC OUTC Can set OPEN Yes, the correct approach is to leave them OPEN
    6 NC OUTD Can set OPEN Yes, the correct approach is to leave them OPEN
    7 EN1 NC Can NC pin(ISOW7843) be applied High or Low externally? Yes, no issues
    10 NC SEL Can NC pin(ISOW7821) be applied High or Low externally? Yes, no issues
    11 SEL IND Can IND(ISOW7843) be set open?  Can be left floating or can apply LOW or HIGH. No effect to IND since OUTD is left floating
    12 NC INC Can INC(ISOW7843) be set open? If not, can NC pin(ISOW7821) be applied High or Low externally? Can be left floating or can apply LOW or HIGH. No effect to INC since OUTC is left floating

    In addition, I'd recommend considering our second generation ISOW7741 devices for future designs. Please see below E2E for details.

    https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/985520/isow7741-emc-inquiry

    Thanks,

    Dushmantha