## DC POWER DISTRIBUTION

###   {#section .unnumbered}

### OVERVIEW

The general configuration of the power distribution for the Near
Detector front end electronics is shown in Fig. 1. All cards and
subcomponents in the system have this same general configuration.

> ![](media/image1.wmf)
>
> **Fig. 1. General Power Distribution Scheme**
>
> **For Near Detector Front End Electronics**

### POWER HARNESSES

The power supplies for the MASTER and MINDER crates are commercial
supplies made by Weiner, Model 6021. The Timing crate power is provide
by a commercial supply, a High Perfection Technology HS-250. A wiring
harness connects the power supply to the crate. Fuses F1 and F2 are
external to the power supply. They are sized for the wire gauge of the
harness, since the supplies can generally put out more power than the
rating of the wires in the harness. In some cases, multiple wires are
used in the power harness for a given voltage. When multiple wires are
used, each wire is individually fused as shown. In all cases, the number
and size of return conductors equals the number and size of the source
conductors. The timing crate power supply harness is integral to the
supply, but in-line fuses have been added where the lines exit the power
supply casing. Specific voltages, harness fusing, and cable gauges are
shown for each crate in the following drawings and sketches.

![](media/image2.wmf){width="5.81875in" height="8.99236111111111in"}

![](media/image3.wmf){width="5.81875in" height="8.99236111111111in"}

![](media/image4.jpeg){width="5.995833333333334in"
height="5.250694444444444in"}

**PCB FUSING**

Power is distributed on crate backplanes through the use of power
planes. The front end cards connect to the power plane through the use
of DIN connectors. The different cards have a different number of power
pins for each voltage. The pins for a given voltage are connected
together at the input to the card, and then routed to a fuse, one fuse
for each voltage. Fuses F3 and F4 are sized based on the rating of the
pins and the total number of pins used for each voltage. The pins for
the power returns come from a common plane on the cards. Generally, the
number of return pins equals or exceeds the sum of the power pins. In
the cases where there are separate digital and analog voltages, the
analog voltages share a common set of return pins, while the digital
voltage has a separate set.

Details for the specific front end cards are provided in the tables that
follow.

  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------
  **[Power Distribution                                                                                                                                                                                                             
  Parameters for the                                                                                                                                                                                                                
  MASTER]{.underline}**                                                                                                                                                                                                             

                                                                                                                                                                                                                                    

  **[Power                                                 **[Power                                                                           **[Backplane                                                                          **[Card]{.underline}**
  Supply]{.underline}**                                    Harness]{.underline}**                                                             Connector]{.underline}**                                                              

                              **Size**                     **Wire**                  **\# Wires**               **\# Wires**                  **\# Pins**                **Total**                    **\# Pins**                   **Size**

  **[Voltage]{.underline}**   **[F1/F2]{.underline}**      **[Gauge]{.underline}**   **[Source]{.underline}**   **[Return]{.underline}**      **[Source]{.underline}**   **[Ampacity]{.underline}**   **[Return]{.underline}**      **[F3/F4]{.underline}**

                                                                                                                                                                                                                                    

  +5V                         NONE                         00                        1                          1                             6                          9 A                          47                            7 A
  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------

**Table 1. Power Distribution Parameters for the MASTER**

  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------
  **[Power Distribution                                                                                                                                                                                                             
  Parameters for the                                                                                                                                                                                                                
  MINDER]{.underline}**                                                                                                                                                                                                             

                                                                                                                                                                                                                                    

  **[Power                                                 **[Power                                                                           **[Backplane                                                                          **[Card]{.underline}**
  Supply]{.underline}**                                    Harness]{.underline}**                                                             Connector]{.underline}**                                                              

                              **Size**                     **Wire**                  **\# Wires**               **\# Wires**                  **\# Pins**                **Total**                    **\# Pins**                   **Size**

  **[Voltage]{.underline}**   **[F1/F2]{.underline}**      **[Gauge]{.underline}**   **[Source]{.underline}**   **[Return]{.underline}**      **[Source]{.underline}**   **[Ampacity]{.underline}**   **[Return]{.underline}**      **[F3/F4]{.underline}**

                                                                                                                                                                                                                                    

  +12 V                       25 A                         10 Ga.                    2                          2                             6                          9.0 A                        20 (Analog)                   3 A

  +5 V Ana                    25 A                         10 Ga.                    2                          2                             3                          4.5 A                        20 (Analog)                   2 A

  +3.3 V                      25 A                         10 Ga.                    2                          2                             6                          9.0 A                        20 (Analog)                   4 A

  -5 V                        25 A                         10 Ga.                    1                          1                             3                          4.5 A                        20 (Analog)                   1 A

  -12 V                       25 A                         10 Ga.                    1                          1                             3                          4.5 A                        20 (Analog)                   0.25 A

                                                                                                                                                                                                                                    

  +5 V Dig                    25 A                         10 Ga.                    2                          2                             3                          4.5 A                        7 (Digital)                   2 A
  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------

**Table 2. Power Distribution Parameters for the MINDER**

  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------
  **[Power Distribution                                                                                                                                                                                                             
  Parameters for the                                                                                                                                                                                                                
  KEEPER]{.underline}**                                                                                                                                                                                                             

                                                                                                                                                                                                                                    

  **[Power                                                 **[Power                                                                           **[Backplane                                                                          **[Card]{.underline}**
  Supply]{.underline}**                                    Harness]{.underline}**                                                             Connector]{.underline}**                                                              

                              **Size**                     **Wire**                  **\# Wires**               **\# Wires**                  **\# Pins**                **Total**                    **\# Pins**                   **Size**

  **[Voltage]{.underline}**   **[F1/F2]{.underline}**      **[Gauge]{.underline}**   **[Source]{.underline}**   **[Return]{.underline}**      **[Source]{.underline}**   **[Ampacity]{.underline}**   **[Return]{.underline}**      **[F3/F4]{.underline}**

                                                                                                                                                                                                                                    

  +12 V                       25 A                         10 Ga.                    2                          2                             3                          4.5 A                        20 (Analog)                   1 A

  -5 V                        25 A                         10 Ga.                    1                          1                             3                          4.5 A                        20 (Analog)                   1 A

  -12 V                       25 A                         10 Ga.                    1                          1                             3                          4.5 A                        20 (Analog)                   1 A

                                                                                                                                                                                                                                    

  +5 V Dig                    25 A                         10 Ga.                    2                          2                             3                          4.5 A                        7 (Digital)                   2 A
  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------

**Table 3. Power Distribution Parameters for the KEEPER**

  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------
  **[Power Distribution                                                                                                                                                                                                             
  Parameters for the                                                                                                                                                                                                                
  VTM]{.underline}**                                                                                                                                                                                                                

                                                                                                                                                                                                                                    

  **[Power                                                 **[Power                                                                           **[Backplane                                                                          **[Card]{.underline}**
  Supply]{.underline}**                                    Harness]{.underline}**                                                             Connector]{.underline}**                                                              

                              **Size**                     **Wire**                  **\# Wires**               **\# Wires**                  **\# Pins**                **Total**                    **\# Pins**                   **Size**

  **[Voltage]{.underline}**   **[F1/F2]{.underline}**      **[Gauge]{.underline}**   **[Source]{.underline}**   **[Return]{.underline}**      **[Source]{.underline}**   **[Ampacity]{.underline}**   **[Return]{.underline}**      **[F3/F4]{.underline}**

                                                                                                                                                                                                                                    

  +5V                         NONE                         00                        1                          1                             6                          9 A                          47 (total)                    2.5 A

  +12V                        NONE                         6 Ga.                     1                          1                             1                          1.5 A                        47 (total)                    1 A

  -12V                        NONE                         6 Ga.                     1                          1                             1                          1.5 A                        47 (total)                    1 A
  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------

**Table 4. Power Distribution Parameters for the VTM**

  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------
  **[Power Distribution                                                                                                                                                                                                             
  Parameters for the                                                                                                                                                                                                                
  MTM]{.underline}**                                                                                                                                                                                                                

                                                                                                                                                                                                                                    

  **[Power                                                 **[Power                                                                           **[Backplane                                                                          **[Card]{.underline}**
  Supply]{.underline}**                                    Harness]{.underline}**                                                             Connector]{.underline}**                                                              

                              **Size**                     **Wire**                  **\# Wires**               **\# Wires**                  **\# Pins**                **Total**                    **\# Pins**                   **Size**

  **[Voltage]{.underline}**   **[F1/F2]{.underline}**      **[Gauge]{.underline}**   **[Source]{.underline}**   **[Return]{.underline}**      **[Source]{.underline}**   **[Ampacity]{.underline}**   **[Return]{.underline}**      **[F3/F4]{.underline}**

                                                                                                                                                                                                                                    

  +5V                         25A                          10 Ga.                    2                          2                             3                          4.5 A                        9                             2A
  --------------------------- ------------------------- -- ------------------------- -------------------------- -------------------------- -- -------------------------- ---------------------------- -------------------------- -- -------------------------

**Table 5. Power Distribution Parameters for the MTM**