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\title{\textbf{{\LARGE Standard Blocking Output Signal Definition for CTDAH board}}}
\author{Carlos Gil Soriano\\BE-CO-HT\\
\href{mailto:carlos.gil.soriano@cern.ch}{\textbf{\textit{carlos.gil.soriano@cern.ch}}}}
\date{February 23, 2012}
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\begin{abstract}
The aim of this document is defining the Standard Blocking Output Signal of the Pulse
Converter Unit. This shape is compatible with previous versions, depending
upon its use.\\

\textbf{History of changes}\\

This document version has been checked by:\\

This document version has been approved by:\\
\begin{center}
\begin{tabular}{|p{3cm}|p{1.5cm}|p{5cm}|}
\hline
\textbf{Date} & \textbf{Pages} & \textbf{Changes}\\ 
\hline
\hline
 September 19, 2011& All & Initial submission\\
\hline
September 21, 2011& All& Scope reduced to Standard Blocking Output Signal
definition\\
\hline
\end{tabular}
\end{center}
\end{abstract}
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\section{Boards and compatibility}
\subsection{Repetitors and Blocking Generators}
Five Pulse Conversion boards outputting the so-called ''Blocking'' pulse
are known to be working at CERN. Three of them were reported and studied by W.
Heinze \cite{HeinzeReport}:
\begin{itemize}
  \item \textbf{Level Converter -LA boards-}\\
  Due to the VAC transformer ZKB 407/115, the output level is 35 V or 18 V
  depending on the applied voltage to the A30 pin in the 96 pin DIN connector
  --either 24 V for the 35 V output or 12 V for the 18 V one. The length of the
  pulse is 1 $\mu{}s$.
  
  \item \textbf{LAPF-TTL-BLO}\\
  This board was used to provide 4 $\mu{}s$ pulses to SAC and LAF boards. For
  these boards, a longer pulse width is required due to the input low pass
  filter applied in SAC and LAF boards to avoid LINAC noisy environment. It uses
  the same transformer as Level Converter and the output level is reported to be the same.
  
  \item \textbf{LASB-TTL-BLO}\\
  It uses a VAC 409/27 transformer. It outputs a pulse with a high level of
  either 23V or 11V depending upon the voltage supplied to the A30 pin in the 96
  pin DIN connector --24 V or 12 V, respectivelly.
  
\end{itemize}

Apart from these three boards, two more are
actually running in CERN facilities: an 8 Channel Repeater and a 16 channel one.
Both Channel Repeater boards use the same subcircuit in every channel to
output the signal. The main differences between them lie in the power supply
they use and the daisy-chain connector included in the 8 channel version. Thanks
to the daisy-channel two boards can copy the same input by means of a short
interconnecting cable.\\
The output level is 24V for the 8 Channel Repeater and
30V for the 16 channel version. This is due to the use of different power
supplies because of different stocks when they were made. The length of the
pulses ranges from 1.2 $\mu{}s$ to 1.4 $\mu{}s$.

The table below summarizes the information of the repetitors systems:
\begin{center}
\begin{tabular}{|c|c|c|c|}
\hline
\textbf{Board} & \textbf{Input Level} & \multicolumn{2}{|c|}{\textbf{Output
Signal}}\\
\hline
&&Level&Pulse width\\
\hline
& TTL & & \\
8 Channel Repeater & inverted-TTL & 24V & [1.2 $\mu${}$s$,
1.4 $\mu${}$s$]\\ &  10V to 30V &  & \\
\hline
\hline
& TTL &&\\
16 Channel Repeater & inverted-TTL & 30V & [1.2 $\mu{}s$, 1.4
$\mu{}s$]\\ & 10V to 30V& & \\
\hline
\hline
LASB -TTL-BLO & TTL & 11V or 23V & 1.5 $\mu{}s$\\
& inverted-TTL &  & \\
\hline
\hline
LAPF-TTL-BLO & TTL & 18V or 35V&4 $\mu{}s$\\
& inverted-TTL & &\\
\hline
\hline
Level Adapter & TTL & 18V or 35V & 1$\mu{}s$\\
& inverted-TTL & &\\
\hline
\end{tabular}
\end{center}

None of the boards specify the design value of the rise time. Only the trailing
edge is reported for LAPF when the circuit is unloaded \cite{HeinzeLAPF}: 0.3
$ms$. Measurements on both 8 and 16 Channel Repeater show a worst-case rise time
of 100 $\mu{}s$ and a fall time of 400 $\mu{}s$ when the outputs are loaded with
50 $\Omega$.

\subsection{Receivers}
Three boards are reported to be Blocking pulse receivers in CERN facilities:
\begin{itemize}
  \item \textbf{LA-BLO-TTL, LAF-BLO-TTL, CTDAC}\\
  By reading the schematics  \cite{ClaudeDoc} \cite{CTDACSchematics}, an input
  threshold detection around 4.5 V can be inferred from the input net consisting of the 10
  $K\Omega$, 1.5 $K\Omega$ and the 2N2222A NPN switching transistor --$V_{BE}$
  should be around 0.6 V by \cite{2222AFairchild}.\\It is not documented the
  reason why this input value threshold is set.
\end{itemize}

\subsection{Uses of boards}
The boards are used as:
\begin{itemize}
  \item \textbf{Repetitors}
  The 8 and 16 Channel Repeaters, LASB and Level Adapter are used as repetitors.
  \item \textbf{Control signal}
  LAPF is intended to interface VME SAC/LAF boards.
\end{itemize}

\pagebreak
\section{Standard Blocking Output Signal Definition}
As it was shown in the previous section, a wide variety of output shapes are
running together. One common type of output shape will be defined to set a
reference for the design of the new CTDAH board.\\
 
\subsection{Criteria}
The criteria employed to define the output shape is as follows:
\begin{center}
\textit{A board designed for a specific use should be backwards compatible with
existing boards so as to avoid interoperability failure.}
\end{center}
\subsection{Target use}
\begin{center}
\textit{Standard Blocking signals are intended to be used in repetitors.}
\end{center}
\begin{tabular}{p{12cm}}
\rowcolor{yellow}{ \textbf{NOTE}: Due to the fact that just a few boards -5
or less- need a LAPF-TTL-BLO-like shaped pulse, the Standard Blocking signal is
not compatible with wide pulses from LAPF-TTL-BLO boards.}
\end{tabular}



\subsubsection{Repetitor Boards}
To comply with previous designs, the definition for this kind of boards,
\textbf{loaded with 50 $\Omega{}$}, is as follows:
\begin{center}
\begin{tabular}{|c|c|c|}
\hline
\textbf{Parameter} & \textbf{Name} &\textbf{Value} \\
\hline
\hline
$v_{i,H}$ & High level & 24V $\pm$ 1V\\
\hline
\hline
$t_{P_{min}}$&\textit{Minimum pulse width} & 1 $\mu{}s$\\
\hline
$t_{P}$&\textit{Typical pulse width} & 1.2 $\mu{}s$\\
\hline
$t_{P_{max}}$&\textit{Maximum pulse width} & 2 $\mu{}s$\\
\hline
\hline
$t_{r}$&\textit{Rise time} & 150 $ns$ $\pm$ 75 $ns$\\
\hline
\hline
$t_{f}$&\textit{Fall time} & 150 $ns$ $\pm$ 75 $ns$\\
\hline

\end{tabular}
\end{center}



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