Ok, thanks for the info. I appreciate you guys running this down. Jim
________________________________ From: Marcus Müller <marcus.muel...@ettus.com> Sent: Friday, June 11, 2021 3:07 PM To: Marcus D. Leech <patchvonbr...@gmail.com>; Jim Palladino <j...@gardettoengineering.com>; usrp-users@lists.ettus.com <usrp-users@lists.ettus.com> Subject: Re: [USRP-users] Re: N320 1PPS input voltage Hi Jim, The congregation of Marcuses checked with R&D, and we figured out that in fact, the NC7SV157 in U24 was replaced by a SN74LVC2G34, which is OK up to 6.5 V input, in Hardware revisions starting with Rev C. So, if (and only if) you have a N320 in a revision that's C or greater, you're safe. Otherwise, please don't connect a 5V source to the PPS input for now. Best regards, Marcus On 11.06.21 15:58, Marcus D. Leech wrote: > On 06/11/2021 09:45 AM, Jim Palladino wrote: >> Hi Marcus, >> >> Right -- the output of the Octoclock is 5V. I'm not seeing how the N320 can >> accept that >> as an input. The knowledge base article says the N320 expects 5Vpp at the >> 1pps input. >> But the schematics/parts data sheet for the input buffer don't seem to >> support that . . >> . unless I'm missing something. >> >> Thanks, >> Jim > It certainly looks like a potential problem, but I haven't heard of anyone > having 1PPS > failure issues on the N320 when used with > Octoclock--pretty sure it was tested with Octoclock prior to release. But > I'll check > with R&D. > > >> >> ------------------------------------------------------------------------------------------ >> *From:* Marcus D. Leech <patchvonbr...@gmail.com> >> *Sent:* Friday, June 11, 2021 9:39 AM >> *To:* usrp-users@lists.ettus.com <usrp-users@lists.ettus.com> >> *Subject:* [USRP-users] Re: N320 1PPS input voltage >> >> On 06/11/2021 09:11 AM, Marcus Müller wrote: >> > Hello Jim, >> > >> > >> > hm, that knowledge base article must be wrong: The octoclock internally >> > only has a 3.3V >> > supply. But before I say something wrong here, let me check back. >> > >> > >> > Best regards, >> > >> > Marcus >> The 1PPS outputs on the Octoclock are bufered by 7404 inverters, which >> appear to have a 5V Vcc. >> >> > >> > >> > On 11.06.21 14:17, Jim Palladino wrote: >> > >> >> Hello, >> >> >> >> We are planning on using an octoclock with several devices, including an >> >> N320. The >> >> octoclock outputs a 5V 1pps signal, but I'm confused about the N320 1pps >> >> input. >> >> >> >> According to >> (https://urldefense.proofpoint.com/v2/url?u=https-3A__kb.ettus.com_N320_N321-29-3A&d=DwIF-g&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=XUEEtUEfpaAEGxRI-WGuqHauOvsPdD2NZkfwDnwpYx0&m=-9vS_HYCWF4BKKIX7QR3SO2LJ3yD1MyEElYsX5a8WMs&s=TdFHQJNItGehIsL1D4yXezIfq_vO05AvF1_lMSyNpHs&e= >> >> "PPS - Pulse Per Second Using a PPS signal for timestamp synchronization >> >> requires a >> >> square wave signal with the following a 5Vpp amplitude." >> >> >> >> If I look at the schematics for the N320, on page 15, >> >> >> (https://urldefense.proofpoint.com/v2/url?u=https-3A__kb.ettus.com_images_f_f4_USRP-5FN3XX-5FMB-5FSchematic.pdf&d=DwIF-g&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=XUEEtUEfpaAEGxRI-WGuqHauOvsPdD2NZkfwDnwpYx0&m=-9vS_HYCWF4BKKIX7QR3SO2LJ3yD1MyEElYsX5a8WMs&s=6JTHdP9IoYFRQhn24LgJjEofkuFwgAsHTs9iHhgMuBg&e= >> <https://urldefense.proofpoint.com/v2/url?u=https-3A__kb.ettus.com_images_f_f4_USRP-5FN3XX-5FMB-5FSchematic.pdf&d=DwIF-g&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=XUEEtUEfpaAEGxRI-WGuqHauOvsPdD2NZkfwDnwpYx0&m=-9vS_HYCWF4BKKIX7QR3SO2LJ3yD1MyEElYsX5a8WMs&s=6JTHdP9IoYFRQhn24LgJjEofkuFwgAsHTs9iHhgMuBg&e=>) >> they show that the input >> >> 1pps signal goes through an NC7SV157. Vcc for that is 3.3V in the >> >> schematics. >> >> >> >> According to the datasheet, the absolute maximum rating on the input is >> >> 4.3V. >> >> >> "https://urldefense.proofpoint.com/v2/url?u=https-3A__www.onsemi.com_pdf_datasheet_nc7sv157-2Dd.pdf&d=DwIF-g&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=XUEEtUEfpaAEGxRI-WGuqHauOvsPdD2NZkfwDnwpYx0&m=-9vS_HYCWF4BKKIX7QR3SO2LJ3yD1MyEElYsX5a8WMs&s=XPmiCDRDfM2wVtI1g4KChC9dkOJhMyrqBTMv_Rx01Xg&e= >> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.onsemi.com_pdf_datasheet_nc7sv157-2Dd.pdf&d=DwIF-g&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=XUEEtUEfpaAEGxRI-WGuqHauOvsPdD2NZkfwDnwpYx0&m=-9vS_HYCWF4BKKIX7QR3SO2LJ3yD1MyEElYsX5a8WMs&s=XPmiCDRDfM2wVtI1g4KChC9dkOJhMyrqBTMv_Rx01Xg&e=>" >> >> >> >> So, I'm not sure how the N320 can safely accept a 5V input (from the >> >> octoclock or other >> >> device). >> >> >> >> Thanks, >> >> Jim >> >> >> >> >> >> _______________________________________________ >> >> USRP-users mailing list -- usrp-users@lists.ettus.com >> >> To unsubscribe send an email to usrp-users-le...@lists.ettus.com >> > _______________________________________________ >> > USRP-users mailing list -- usrp-users@lists.ettus.com >> > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >> _______________________________________________ >> USRP-users mailing list -- usrp-users@lists.ettus.com >> To unsubscribe send an email to usrp-users-le...@lists.ettus.com > > > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com
_______________________________________________ USRP-users mailing list -- usrp-users@lists.ettus.com To unsubscribe send an email to usrp-users-le...@lists.ettus.com
