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SN65HVD1792: ISL8491IB replacement

Prodigy 30 points

Replies: 2

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Part Number: SN65HVD1792

On a card I am working on there are two rs-232 to rs-485 circuits, one contains one ISL849IB and is connected to a max232.  The second circuit again has a max232 but then has two ISL849IBs that share an RS-485 bus line.  I have replaced all 3 ISL849IB chips with SN65HVD1792s.  The first circuit works perfectly, the second circuit does not.

The first circuit takes rs-232 in, communicates via TTL through Schmitt triggers which then go to the ISL849IB which is then connected to a rs-485 bus line.

The second circuit has two incoming rs-232 signals that go to the max232.  The max232 TTL (through Schmitt triggers) for each rs-232 bus each go to an ISL849IB.  Both of these ISL849IBs share a single rs-485 bus however.

I would like to get in touch with an engineer from TI directly as I could share a capture of the relevant portions of the schematics.  I cannot do so on a public forum though.  I have a feeling someone with expertise on this subject could spot my problem in a matter of minutes.

  • Hi Brett,

    I can help out.  Do you mind if I send you an email directly using the address registered to your ti.com account?  I think I will need to see a schematic snippet as you've mentioned, since I don't have a datasheet for the ISL849IB and I'm having trouble understanding all the connections you've described.

    Regards,
    Max

  • In reply to Max Robertson:

    That would be great.

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