more comments about flex cable and power supply

diff --git a/electronics/electronics2013.pdf b/electronics/electronics2013.pdf
index e945aa0f7e1a0a12bad1630f4d9c34ec7a8235ff..828da905d192570c4bc0223ded5fce5ba2013d5b 100644 (file)
Binary files a/electronics/electronics2013.pdf and b/electronics/electronics2013.pdf differ

diff --git a/electronics/electronics2013.tex b/electronics/electronics2013.tex
index efc3b850a3fd11eea8d6fc1fbcf31a170b3c68de..ce86dce78b428e59ec32cad3320e4984922ca76e 100644 (file)
--- a/electronics/electronics2013.tex
+++ b/electronics/electronics2013.tex
@@ -20,7 +20,7 @@
 \begin{center}
  \includegraphics[width=.8\textwidth]{./boardchain.png}
 \end{center}
-\caption{The setup of the new read-out board chain between sensor and read-out controller. Redish,
+\caption{The setup of the new read-out board chain between sensor and read-out controller. Reddish,
 Bluish and Yellowish colors show the origin of components.}
 \end{figure} 
 
@@ -50,8 +50,8 @@ length. \final{The final setup will most likely use different cables with better
 improved handling.} Cables as well as connectors will be bought by GSI.
 
 Table \ref{iocount} gives a rough count of necessary I/O. The final number of connections required
-will strongly depend on the realisation of the converter board, mainly with respect to the data
-busses for switches and ADCs. A.t.m. there are 14 I/O per converter board plus 12 I/O per sensor.
+will strongly depend on the realization of the converter board, mainly with respect to the data
+buses for switches and ADCs. A.t.m. there are 14 I/O per converter board plus 12 I/O per sensor.
 Note that this setup is for M26 sensors only where we will not have any ladders larger than 2
 sensors. The number of I/O for the final sensor will be different.
 
@@ -71,7 +71,7 @@ Voltage and JTAG switch (Bus) & 0 & 4 (4) & 0 & 1 (1) \\
 Total & 1 & 13 (6) & 10 & 2 (2)\\
 \end{tabularx}
 \caption{Inputs/Outputs from the FPGA to the converter board. The number in
-parantheses shows the number of I/O that could be replaced by a non-differential connection.}
+parentheses shows the number of I/O that could be replaced by a non-differential connection.}
 \label{iocount}
 \end{table}
 
@@ -109,7 +109,7 @@ ADC are used, the remaining channel can be connected to the ground sense wire.
 
 The on-board ADC should provide about 1 MSPS and a SPI (or similar) interface. AD7928 is a
 possible candidate for single ended measurement.
-(I do not have a differential ADC in mind yet, but the ADC implemented in Attiny microcontrollers
+(I do not have a differential ADC in mind yet, but the ADC implemented in ATtiny micro-controllers
 does fit the requirements despite conversion speed.)
 
 
@@ -144,13 +144,26 @@ All signals from and to the sensor should be fed through LVDS buffers to reduce
 sensors' output drivers and to improve signal quality.
 
 
-\subsection{Test Features}
+\subsection{Power Supply}
+The CB needs to generate three voltages for each sensor. They should be independent on the board,
+but as a test feature, one block should be able to serve both connected sensors. That is, provide
+jumpers to bridge power supplies of both sensors to test running several sensors in parallel on all
+three voltages.
+
+Estimated power consumption of the converter board (per sensor):
 \begin{itemize*}
-  \item The final setup will profit if the number of voltage regulators is reduced. We should
-prepare a test to run several sensors in parallel on one supply. That is, provide jumpers to bridge
-power supplies of both sensors to test running several sensors in parallel on all three voltages.
+ \item VDD Analog: 3.3~V, 0~mA
+ \item VDD Digital: 3.3~V, 0~mA
+ \item V Clamping: $\approx$ 0~V, 2~mA
+ \item VCC Board: 3.3~V, t.b.d.~mA
 \end{itemize*}
 
+To improve the noise environment and the stability of voltages, linear regulators can be used.
+Using a supply voltage of e.g. 4~V for the CB would result in an estimated 0.5~W higher power loss
+on the board as compared to switching converters. This seems acceptable since cooling with fans
+will be possible (if needed) even in the final set-up with many sensors.
+
+
 
 
 \subsection{Components}
@@ -159,18 +172,49 @@ power supplies of both sensors to test running several sensors in parallel on al
 current, smaller form factor), e.g. BLM41 and similar.
 \end{itemize*}
 
+\clearpage
 \section{Cable CB to FEB}
-First iteration: Reuse old flex cables, two old cables should provide enough connections to the
-front-end board, also with respect to the number of additional monitoring signals needed.
+First iteration: Reuse old flex cables. The estimation in table \ref{CbFebCable} shows that the
+scheme uses 35 wires per sensor plus four per FEB. In total 74 wires for one 2-sensor FEB board.
+Two old cables should provide enough connections to the front-end board.
+\final{Sense lines for VDiscr might be removed for the final version and replaced by test pads on
+the FEB for measurement during commissioning.}
 
 Later, a new cable can be developed taking into account that it will be fully placed outside the
 acceptance of the detector. I.e. a two-layer cable with broad ground and power planes should
 provide a much cleaner voltage for the sensor. One important fact is that this cable has to be fed
-into the vacuum vessel. The total length of the cable must at least 50 cm in the final version.
+into the vacuum vessel. \final{The total length of the cable must at least 50 cm in the final
+version.}
+
+The pin-out on the FEB should be slightly changed, at least an additional sense line for ground up
+to the sensor is needed.
 
-The pin-out on the FEB should be slighly changed, at least a additional sense line for ground up to
-the sensor is needed. Using sense lines for the supply voltages would be nice but is most liekly
-not viable with the current bonding / cable set-up.
+
+\begin{table}[htb]
+ \centering
+\begin{tabular}{l|c|c|c|c}
+ & \multicolumn{2}{c|}{\textbf{per Sensor}} & \multicolumn{2}{c}{\textbf{per
+FEB}} \\
+\textbf{Purpose} & \textbf{Single} & \textbf{Differ.} & \textbf{Single} & \textbf{Differ.}\\
+\hline
+Sensor Data & - & 4 & - & -\\
+Sensor Control & - & 1 & 2 & - \\
+JTAG & 2 & - & 2 & - \\
+Temperature & 1 & - & - & - \\
+Analog VCC & \discuss{2} & - & - & - \\
+Analog GND & \discuss{5} & - & - & - \\
+Clamping VCC & 1 & - & - & - \\
+Digital VCC & \discuss{1} & - & - & - \\
+Digital GND & \discuss{2} & - & - & - \\
+Sense VCC & 2 & - & - & - \\
+Sense GND & 1 & - & - & - \\
+Sense VDiscr & 8 & - & - & - \\
+\hline
+Total & 25 & 5 & 4 & 1 \\
+\end{tabular}
+\caption{Connections between CB and FEB.}
+\label{CbFebCable}
+\end{table}
 
 \clearpage
 \section{Front-end Board (FEB)}
@@ -179,8 +223,9 @@ short sides and with an additional broad connector on the side towards the CB.
 
 \subsection{Jtag}
 The switches for bridging of sensors will be located on the CB as before, so no active
-components are necessary for Jtag.
-\discuss{Termination might be foreseen if necessary}.
+components are necessary for Jtag. \discuss{Termination might be foreseen if necessary}. Using
+differential signaling between CB and FEB would be nice although active components would be
+required on the FEB to convert the signal back to single ended.
 
 
 \subsection{Data}
@@ -199,5 +244,9 @@ final board and there is no harm if such a circuit fails.
 There is no need to develop a new sensor flex print cable at the current stage. The final length of
 this cable is likely to be about 15 cm.
 
+The pin-out of the connector on the FEB has to be changed to allow for an additional GND sense line.
+Using sense lines for the supply voltages would be nice but is most likely
+not viable with the current bonding / cable set-up.
+
 \end{document}