(Also see EL-3162.) This board lives in the CCD controller chassis and was designed to break out the various signals that originate on the SDSU utility board. In essence, we are using the general digital and analog I/O bits to accomplish the various auxiliary functions needed for the operation of the CCD controller.

Sheet 1

The top of this sheet shows the 96-pin din connector that is wired pin-for-pin to the Utility Support board. The signals that are used are all labeled. Notice that the connector on the right side of each group, P1, is used as a test probe connector for troubleshooting. This connector faces directly out from the board and the interconnecting cable from the Utility Support board is attached to the connector behind it. On the bottom of the sheet is, on the left-hand side, P7 that brings in the power for the board. As with the other cards in the system, the +5 volt logic ground is separate from the +/- 16 volt analog ground. The middle, bottom of the drawing is the local filtering for the power supply voltages. On the bottom right-hand side of the sheet is a connector, P8, that can be used in applications where a local readout of the temperature of the dewar is required. This, of course, requires specific programming to be in place to be implemented.

Sheet 2

(Also see EL-1187) This sheet shows the connections for the Power Monitor board. The Power Monitor board monitors the voltages of the various power supplies and sends signals to the SDSU2 system if any of the supplies fail. It also enforces the sequence in which power can be applied to the dewar electronics. It will not let the ANALOG_SW_EN signal to be asserted unless the +38 volt supply in on and up to voltage. In turn, it will not allow the +38 volt supply to turn on until the 16 volt supplies are on and up to voltage. The 16 volt supplies will not be allowed to turn on unless both the 5 volt supply is up and the 120 VAC is within limits. Beyond this, the Utility Board, under program control, must also send enables to the power monitor board. These signals are shown on the left-hand side of this sheet. Each of them are feed through opto-isolators to buffer them and protect that CCD controller in case of over voltage, line spikes or other failures. The signal ANALOG_SW_EN_REQ is sent by the controller as a request to the Power Monitor board. If the conditions are right and the Power Monitor does enable the switches, that enable signal comes back on pin 5 of P9 where transistor Q20 and optic isolator U11 convert the signal and apply it to the 74LS240 line driver. After an inversion of the signal, it is routed to both the analog switch boards via P14 (sheet 3) and back to the Utility Support board via pin C17 of connector P2 (sheet 1.) The EXRESET signal is sent from the Power Monitor if the 5 volt supply goes below its set point of about 4.6 volts. Again, the signals on the left side of the sheet, ANALOG_SW_EN_REQ, 15V_ENABLE, and 34V_ENABLE are outputs sent to the Power Monitor and the signals on the right-hand side are signals returning from it.

Sheet 3

This sheet is concerned with the signals that enter and exit on P14, and go to the EL-3195 Power and Miscellaneous Signal board. The opto-isolators at the top of the page are used to input signals that originate at the Shutter Controller Box, EL-1183. These signals are read back on digital input bit Din0 through Din4 and inform the controller of the status of the dewar shutter. Also at the top is the shutter output signal SHUTTER_CLOSE. This signal is high when the controller wants the shutter open and low when it wants it closed. This signal is also isolated to protect the CCD controller. At the lower left-hand side of the drawing are the heater and temperature diode lines. The temperature diodes are connected to a constant current source shown on sheet 4. The voltage developed across the diode arrives at the board on pins 15 and 24 of P14 and is then fed to analog inputs on the Utility board via pins A32 and C32 of the connector P2 (sheet 1.) The heater voltages originate on the SDSU Utility board as analog outputs Aout1 and Aout2. These signals go directly to the resistor(s) mounted in the dewar via pins 17 and 22 of P14 (and then through the Power and Miscellaneous Signal board.) The controller monitors the temperature of the CCD and regulates it via these heater resistors.

Sheet 4

This sheet shows the available extra temperature diodes that can be mounted in the CCD dewar. For mosaics like the DEIMOS project, these can be used to monitor the temperatures at the various CCDs. The normal configuration of a single CCD chip works fine with the two temperature diodes available with the normal SDSU system but with a mosaic of chips two temperature inputs are generally not enough to give a good picture of what is going on in the dewar. Thus the Utility Support board supplements the system with an additional temperature diode circuit for each of the controller’s signal chains. To do this, the constant current drive circuit is replicated eight times with a unique drive available at each of the CCD connectors P3 through P6 and P10 through P13. In the lower right-hand portion of the sheet is an analog multiplexer. Each of the above mentioned current drive circuits are also wired to an input to the multiplexer. The controller can read any one of these eight levels by selecting the CCD of interest on the CCD select lines CCD_SEL_0 through CCD_SEL_2 and reading the corresponding level on the Utility board’s analog input Ain10. Op-amp U26 buffers the output of the multiplexer before it is sent to the Utility board.

Sheet 5 and Sheet 6

These sheets are identical except for the circuit number. Sheet 5 contains heater circuits for CCDs 1 through 4 and sheet 6 contains heater circuits for CCDs 5 through 8. At the bottom left of sheet 5 is a precision 10 volt reference circuit for the serial DACs U12 and U13. The LT1021BCN8-10 is a precision 10 volt reference IC. The LT1097CN8 is a low noise op-amp that employed to regulate the output of the circuit via the feedback resistor R95. The MAX536BCPE is a quad, 12-bit D/A with a serial input. The control signals for the DACs consist of a serial clock, DACS_SCLK, the serial data, DACS_SD1, and the chip select DACS_CS. The serial data is daisy chained from U12 to U13. In brief, these chips accept serial data when the CS signal is pulled low and act on it when the CS goes back high. The serial data is transferred in 16-bit words with the four MSB bits containing address and command information. The other 12 bits contain the D/A value to be output by the selected DAC. (http://dbserv.maxim-ic.com/quick_view2.cfm?pdf_num=1125) Each of the four analog outputs are wired to a voltage follower/current source. These supply the power to drive four, or between both sheets, eight extra heater resistors that can be mounted on the mosaic backplane. The outputs of these circuits go to pin 2 of the CCD connectors P3 through P6 and P10 through P13.

Sheet 7

(Also see EL-3161) The eight connectors at the top of this page distribute the heater drive, temperature readout, and power supply voltages to the EL-3194 CCD cable interconnect boards. Also, each connector has a BIAS_MUX_CCDn signal that returns from the cable interface board. This is explained in the EL-3194 write-up but in essence, we are able to read back any of the bias levels that are sent out to the CCD dewar on this line. Each of these lines is wired to the analog mux at U18 in the lower left-hand area of the diagram. The CCD_SEL lines can then be set to read any one of these bias levels back via the buffer amplifier U27 at analog input Ain9 of the SDSU Utility board.

Sheet 8

(Also see EL-3161) The last sheet shows the connections from the Clock Interconnect boards. Each of the SDSU2 Clock Driver boards is capable of sending a waveform out on an SMB connector at the front of the board. This allows us to monitor any one of the clock waveforms by the following procedure: first, select its address internally on the clock board, next, set the CCD_SEL address via the Utility board, and finally, read the CLOCK_MUX_OUT signal at analog input Ain8. For single or dual chain controllers only the signal from Clock Board #1 is available. In other configurations, as many as five Clock Driver boards may be in the system.