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docs: resolve the +1V1 label mystery and close remaining schematic open items

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User confirmed TLV62568 (U1) outputs 1.1V, explaining the +1V1 label
found near the VCCAUX ferrite (L2) during the schematic review: it
belongs to U1's own real output net, merely nearby on the page layout,
not routed through the ferrite. VCCAUX remains 2.5V as required by the
real Lattice datasheet.

All three schematic "open items" from the earlier review are now
resolved: TLV62568 EN (R3=499k, confirmed via BOM), the +1V1 label
(false alarm, explained above), and the JTAG pull-up array (confirmed
8 discrete 0402 parts via BOM, not a bussed package -- no polarity
limitation). Only the boot-flash net-name typo (FGPA/FPGA + SCLK/CLK)
remains as a real, open schematic fix, and the FPGA grade discrepancy
(8BG381I vs 8BG381C) remains to be confirmed.

Compiled clean (47 pages, 0 errors).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
This commit is contained in:
michele
2026-09-07 19:42:46 +02:00
co-authored by Claude Sonnet 5
parent 1e36853072
commit 22e226a087
2 changed files with 18 additions and 12 deletions
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hardware/v2/docs/datasheet/files/docs/datasheet/v2-en/FPGA-Neural-V2-Datasheet-EN.pdf
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hardware/v2/docs/datasheet/files/docs/datasheet/v2-en/chapters/10-hardware.tex
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@@ -380,19 +380,25 @@ original review was a misread of the schematic image, not a real
error.
\end{fnnote}
\subsection{Open items (not resolvable from the schematic image alone)}
\subsection{Open items --- all resolved as of this pass}
\begin{itemize}
\item \code{TLV62568}'s EN pin: is \code{R3}=499\,k$\Omega$ actually on
EN, and to which rail?
\item A \code{+1V1} label appears near the VCCAUX ferrite (L2)/its
decoupling (C8/C9) --- VCCAUX must remain 2.5\,V after the
ferrite (a ferrite bead filters, it does not change DC voltage);
confirm this label belongs to a different, merely nearby net.
\item JTAG pull-up array (R5--R8, 4.7\,k$\Omega$): TDI/TDO/TMS need a
pull-up to VCCIO8, TCK needs a pull-\emph{down} to GND --- a
single bussed (common-node) array package cannot provide both
polarities. Confirm TCK is wired separately from the other
three.
\item \code{TLV62568}'s EN pin: \textbf{resolved} --- \code{R3}=499\,k$\Omega$
confirmed on EN (BOM, \S\ref{sec:bom}), matches TI's own
reference circuit.
\item The \code{+1V1} label near the VCCAUX ferrite (L2): \textbf{resolved,
false alarm}. \code{TLV62568} (U1) itself outputs 1.1\,V (confirmed
by the user directly, matches the R1/R2 divider calculation in
\S\ref{sec:power-addendum}) --- the label belongs to U1's own
real output net, merely placed nearby on the schematic page, not
routed through the VCCAUX ferrite. VCCAUX remains 2.5\,V as
required.
\item JTAG pull-up array (R5--R12, 4.7\,k$\Omega$): TDI/TDO/TMS need a
pull-up to VCCIO8, TCK needs a pull-\emph{down} to GND ---
\textbf{resolved}: the real BOM (\S\ref{sec:bom}) confirms these
are 8 \emph{discrete} 0402 parts, not a single bussed-array
package, so each can carry its own correct polarity (still
needs a final visual confirmation of the actual net-by-net
wiring, but the package-level limitation is ruled out).
\end{itemize}
\section{Bill of Materials (real, KiCad-exported, 2026-09-07)}