A_Card Description ------------------------- Original Rev. 20-OCT-1996 Most Recent Rev. 9-FEB-1998 General Description: The A_Card provides: analog signal processing, a 14 bit ADC, and digital line drivers for sending the converted signal over a cable to the VME equipment. Analog Signal Processing: The purpose of the analog signal processing is to receive a high impedance wide bandwidth analog signal from the TCM2620 array and then to provide: voltage gain, bandwidth filtering, DC voltage shift, and a low impedance output drive for sending the signal into the ADC. Provision is made for a common mode choke at the input to the analog section to help isolate the ground structures of the 4 A_Cards that are driven by the TCM2620 array. The signal that is received from the TCM2620 array will have a typical "zero signal" voltage of +3.1 Volts and a typical "full scale" value of +1.3 Volts. This signal must receive voltage gain and shift so that at the end of the analog processing it has a "zero signal value of -2 Volts and a "full scale" value of +2 Volts. The output of the analog signal processing section must be capable of driving the 200 Ohm plus 15 pFd input load of the ADC. The waveforms processed by the analog signal processing section will have many Fourier components. All bandwidth filtering done in the analog section must take this into consideration and try to preserve the shape of the signal that it receives from the TCM2620 array. Although it is not understood what the high frequency roll off should be, it is probably on the order of 10 MHz. The design of the analog section tries to make it easy to change the capacitors that determine the high frequency roll off (or even to run without the capacitors to check full bandwidth operation). Along the analog processing chain there are a number of test points for attaching a voltmeter or oscilloscope. These test points have an isolation resistor and a connection to the analog ground plane. The analog processing section contains a trim pot to set the zero signal voltage level that is sent to the ADC. The following table shows the voltage level at various steps during the analog signal processing: First Second Third OpAmp OpAmp OpAmp Input Photon TCM2620 Output Output Output to the Signal Output (+6 V Ref) (0 V Ref) (+39 mV Ref) ADS-946 ------ ------- ---------- --------- ------------ ------- Max. +1.3 V -1.351 V -1.688 V +2.2 V +2.0 V Mid. +2.2 V +0.057 V +0.071 V 0 V 0.0 V Zero +3.1 V +1.464 V +1.831 V -2.2 V -2.0 V SPAN 1.8 V 2.816 V 3.520 V 4.4 V 4.0 V ---- Required <-- +1.564 --><-- +1.250 --><-- -1.250 --><-- +0.909 --> Signal Gain <------------- - 2.444 ---------------> -------- Resulting Reference <-- -0.564 --> <-- +2.250 --> Gain -------- ADC: The ADC input receives the output from the analog signal processing section. The clock signal for the ADC comes from the D_Card. This signal is series terminated on the D_Card which is appropriate for driving the CMOS clock input on the ADC. The ADC output drives 74HCT541 buffers through 470 resistors. The purpose of the resistors and the buffers is to reduce the digital switching currents seen by the ADC and its ground structure. The output of the buffers drives 100324 TTL to differential ECL converts. The outputs of the 100324 have 56 Ohm pull down resistors to Vtt. These signals are the output from the A-Card. Besides the 14 bits of ADC data the A_Card supplies the two high order data bits: Data_14 and Data_15 and is capable of driving the 17th pair on the twist and flat output cable. These three "extra" output signals may be driven by either jumper controlled static signals or by the ADC Clock signal or by the ADC End_of_Conversion signal. The Datel ADS-946 converter is mounted in a Datel HS-24 heat sink and plugs into the A_Card using Mill-Max 614-93-624-31-018 DIP socket carrier. Power Supplies: This card receives separate Analog and Digital power supplies. In order to isolate the remote power supplies from the ground structure on A_Card, the supplies are filter by 15 uH chokes before they are used on A_Card. The filter inductors are placed on the supply lines, the return lines, and the sense lines. The power supplies, located back with the VME equipment, are all remote sensed on both the four A_Cards and the D_Card. Because of the series resistance (about three Ohms) of the small inductors in the sense lines; the sense signal that is sent back to a power supplies is an "average" of the potential on the 4 or 5 cards that consume power from that supply. On the four A_Cards the Digital power supplies are used directly. The bulk + & - 10 Volt analog supplies pass through regulators before they are used. There is a -5V regulator to provide analog power for the op-amps and the ADC. The +5V regulator supplies analog power to the second op-amp and to the ADC. The +6V regulator supplies analog power to the first op-amp and supplies the offset reference for the first op-amp. There is an adjustable third positive analog regulator on each A_Card that is used to supply the TCM2620. Each of the four A_Cards supplies a different potential to the TCM2620. One A_Card supplies the TCM2620's analog section, another supplies the array's digital section, a third supplies the V_Clamp potential, and the fourth A_Card supplies the D_Sub potential to the TCM2620. These regulators that supply the TCM2620 are adjustable. They are setup to have the following adjustment ranges. Potential Supplied Regulator to the TCM2620 Array Adjustment Range -------------------- ------------------- Analog Section 4.75 V : 5.25 V Digital Section 4.75 V : 5.25 V V_Clamp Potential 1.30 V : 3.10 V D_Sub Potential 3.50 V : 4.00 V There are two protective devices on each A_Card: The regulator that supplies the TCM2620 has at its output both a reverse voltage clamp diode and a 6.2 Volt zener clamp diode. The A-Card circuit board contains mounting locations for back to back silicon diodes to connect the ADC's +5V analog supply to the ADC's +5V digital supply. Because the two +5V supplies come from different sources there is the possibility that one of these sources would fail while the other is operating. If the ADS-946 ADC can be damaged by this condition then these back to back diodes would protect against this problem. A_Card Ground Structure: The A_Card uses a ground structure that is designed to prevent "digital ground currents" from flowing through the ground structure under the analog section of the board. This includes separate ground pin for connecting the analog section of the A_Card to the M_Card and for connecting the digital section of the A_Card to the M_Card. The A_Card has two outer trace layers and three internal planes. One of the planes layers is split into the digital and analog ground planes. The second planes layer is split into positive analog supplies and positive digital supplies. The third planes layer is split into negative analog and digital supplies. General Layout of the A_Card: << << Signal Flow << << +-------------------------------------------------+ | P T H I +------\ +---------+ | | U T C S | \ | Analog | | +-+ L L T O | ADC / | Section | | | | L +------/ +---------+ +-+ To | | t B R |J| From VME |J| D o U E |3| Dewar |2| O F S +-+ | | W E | +-+ N C Analog Supply Regulators | | L | | Power Supply Filters | | +-----------------------------------+ | +------| J1 |------+ +-----------------------------------+ J1 2x70 Power and Ground and ADC Clock 2 row 140 pins total connections to the M_Card J2 2x17 Digital Data output. This digital data 2 row 34 pins total goes to the VME equipment location J3 2x12 Receives the analog signal from the TCM2620 2 row 24 pins total and supplies one of the four power supplies to the array. Test Points on the A-Card: -------------------------- Label on Reference Silkscreen Series Designator COMP - SOLDER Function Resistor ------------ ------------- ------------------------------- -------- TP-1 J10 1 - TP1 Raw input signal 100 Ohm J11 G G Ground TP-2 J12 2 TP2 Output of the 1st OpAmp stage 100 Ohm J13 G G Ground TP-3 J14 3 TP3 Output of the 2nd OpAmp stage 100 Ohm J15 G G Ground TP-4 J16 4 TP4 Output of the 3rd OpAmp stage 100 Ohm aka the input to the DAC J17 G G Ground TP-5 J50 5 TP5 The "Array" supply voltage to the TCM - TP-6 J20 6 TP6 Reference voltage to the 3rd OpAmp stage - Jumpers on the A-Card: ---------------------- Label on Reference Silkscreen Designator COMP - SOLDER Function ------------ ------------- ------------------------------------------ J76 - CLK J76 is a copy of the ADC_Clock signal exactly as it is delivered to the ADC. J90, J91 next to C80 Cosmetic Copper linking the Analog and Digital Ground Planes together. J77 77 77 J77 passes through a 471 resistor, R76 pins 7 and 10, and then into a 74HCT541 buffer, U77 pin ?. J77 is tied to Digital Ground by cosmetic copper. J81 - 81 J81 is tied to U77 pin 12, i.e. the buffered copy of what ever is connected to J77. J79, J82 - +5 These two via's are tied directly to Digital VCC. They can be used to hard wire HI either of the two high order output bits, J83, J84. J80, J85 - G These two via's are tied directly to the Digital Ground Plane. They can be used to hard wire LOW either of the two high order output bits, J83, J84. J83 - 83 J83 is the input to the next to the Most Significant Bit, i.e. D14 (D0:D15). J84 - 84 J84 is the input to the Most Significant Bit, i.e. D15 (D0:D15). J86 - 86 J86 is the input to a section of U80, a 100324 TTL->ECL Translator, that is not connected to anything except pull down resistors. A number of the passive components have their value set by the particular application that a give A-Card will be used in. For example the components that determine the frequency response characteristics of the Analog Processor are picked to match the actually application. Analog Processor Values ----------------------- Built for the TCM-2620 with a Cut Off Frequency of 1 MHz These values were used in A-Card SN# 1:9. Design Value Component Obtainable -------------- ---------------------------- OpAmp #1 R2 = 499 Ohm 499 Ohm 1% 1206 R3 = 280 Ohm 280 Ohm 1% 1206 OpAmp #2 R4 = 499 Ohm 499 Ohm 1% 1206 R5 = 499 Ohm 499 Ohm 1% 1206 C1 = 289 pF 270 pF 5% 0805 NP0 C2 = 217 pF 220 pF 5% 0805 NP0 R6 = 499 Ohm 499 Ohm 1% 1206 R7 = 124 Ohm 124 Ohm 1% 1206 OpAmp #3 R8 = 399 Ohm 402 Ohm 1% 1206 R9 = 222 Ohm 221 Ohm 1% 1206 R10 = 499 Ohm 499 Ohm 1% 1206 C3 = 957 pF 820 pF 5% 0805 NP0 C4 = 239 pF 220 pF 5% 0805 NP0 ADC Feed R11 = 20 Ohms 20 Ohm 1% 1206 C5 = 22 - 56 pF 22 pF 5% 1206 NP0 C6 = 22 - 56 pF 22 pF 5% 1206 NP0 Values of the resistors in the Analog Power Supply Section. ----------------------------------------------------------- R55 and R57 are fixed at 243 Ohm. R59 is fixed at 124 Ohm. +6.0V supply U51 R55 is 243 Ohm so pick R56 to be 915 Ohm. ---> 909 Ohm or +6.5V supply U51 R55 is 243 Ohm so pick R56 to be 998 Ohm. ---> 1.0k Ohm +5V supply U52 R57 is 243 Ohm so pick R58 to be 722 Ohm. ---> 715 Ohm -5V supply U53 R59 is 124 Ohm so pick R60 to be 372 Ohm. ---> 374 Ohm Values of the resistors in the ARRAY Power Supply Section. ---------------------------------------------------------- Note ECO Jump R50 P2-P3 to hold constant the Vout to Vadj resistance. R52 is fixed at 243 Ohm. R50 is fixed at 500 Ohms. The +5_Anl and +5_Dig supplies are 5 Volt output +- 250 mV ---> range 4.750 to 5.250 Volts The DSub supply is 3.75 Volt +- 250 mV. ---> range 3.500 to 4.000 Volts The VClamp supply is 3.1 Volts ---> range 2.1 to 3.6 Volts. There are two possible ways to setup R51 and R52. Depending on the voltage range desired, one arrangement of these ressistors will typically be preferred over the other because it will have a more linear change in supply voltage as the pot R50 is adjusted. Setup #1 or Setup #2 Vadj---+-----------WWW---------Vout Vadj---+-----------WWW---------Vout | R52 | R52 | | +-----+ +-----+ | | R50 | | R50 | V | V +----WWW----+ +----WWW---------WWW----GND | | | R53 | +-----WWW---GND | | | | +----WWW----+ R53 +----------WWW----------GND R51 R51 With R52 is fixed at 243 Ohm, and wanting the following adjustment ranges on the Array Supply, the resistance to GND of the network R50, R51, R53 should be R_Ohms, and then for Setup #2 shown above the values of R51, and R53 are given below: Supply +5_Anl and +5_Dig DSub VClamp ----------------- ------------- ------------- Range Volts 4.750 - 5.250 3.500 - 4.000 2.100 - 3.600 R_Ohms 673.9 770.1 433.2 529.5 163.7 - 452.4 R51 Ohms 1289.8 (1300) 863.2 (866) 1325.7 (1330) R53 Ohms 1411.3 (1400) 869.6 (866) 186.8 (187) The 1% standard values are shown in (). To accomplish wiring R51 and R53 as in Setup #2; just insert the lead from the end of R51 that next to the right hand edge of the board into the same pad hole as the end of R53 that is also next to this board edge. This will ground the right hand board edge lead of both R53 and R51 and thus configure them as in Setup #2. Note the the lead at the other end of R51 can be bent to connect to the center wiper on R50 and thus implement the ECO mentioned at the beginning of this section about the Array Supplies. Collection of all Known ECO's for the A-Card Rev. A --------------------------------------------------- Backwards Tantalum Capacitors C78, C90, and C94 must all be installed with there negative end aligned with the "+" sign in the silk-screen for these parts. The silk-screen for these three tantalum capacitors is backwards ! Array Supplies To accomplish wiring R51 and R53 as described in Setup #2 in the Array Supply Section; just insert the lead from the end of R51 that next to the right hand edge of the board into the same pad hole as the end of R53 that is also next to this board edge. This will ground the right hand board edge lead of both R53 and R51 and thus configure these two resistors as in Setup #2 in the Array Supply Section. Note the the lead at the other end of R51 can be bent to connect to the center wiper on R50 and thus implement the ECO that connects the wiper of R50 to the "R51, Vadjust" end of R50. Offset Adjustment for the Third Stage Op-Amp The plan had been that the offset adjustment in the third stage Op-Amp was only going to have a small adjustment range. The A-Cards were all built with 4.02k Ohm resistors installed in locations R27 and R28. This value together with the 500 Ohm pot R28 and the divide by 2 from R25-R26 gave an offset range of about 146 mV. This was all nice but then the 2nd array tested had a zero photon signal of about 3.5 Volts instead of 3.1 Volts. The best solution may be to boost the Reference to the first stage Op-Amp from 6.0 to 6.5 volts but for now we will try to operate this array by cleaning up all of the offset in the 3rd stage. To do this: Remove R29, Connect the bottom end of pot R28 to Gnd, Change R27 to 768 Ohms. This lets the wiper of pot R28 pull up to 1.5 Volts, i.e. puts a 0.75 volt reference on the third Op-Amp. +6V Supply The plan had been for the V+ supply to the First Stage OpAmp and its reference supply to be 6.0V but with the second Rockwell array it looks better to move this up to +6.5V. So on 6-FEB-1998 A-Cards with serial numbers 1,2,3,4,6 were moved up to +6.5V first stage supply. This was done by changing R56 from 909 Ohm to 1.0K Ohm. A-CARD Resistor Values ----------------------- Values used on A-Card SN#1:9 Reference Value Designator Part Number Geometry Description Installed ---------- --------------- -------- ------------ --------------- R1 pn-CRCW1206111 rc1206 CRCW1206111 110 Ohm 1% R2 pn-CRCW12063010 rc1206 CRCW12063010 499 Ohm 1% R3 pn-CRCW12061690 rc1206 CRCW12061690 280 Ohm 1% R4 pn-CRCW12063010 rc1206 CRCW12063010 499 Ohm 1% R5 pn-CRCW12063010 rc1206 CRCW12063010 499 Ohm 1% R6 pn-CRCW12063010 rc1206 CRCW12063010 499 Ohm 1% R7 pn-CRCW12061690 rc1206 CRCW12061690 124 Ohm 1% R8 pn-CRCW12061910 rc1206 CRCW12061910 402 Ohm 1% R9 pn-CRCW12061910 rc1206 CRCW12061910 221 Ohm 1% R10 pn-CRCW12063010 rc1206 CRCW12063010 499 Ohm 1% R11 pn-CRCW1206220 rc1206 CRCW1206220 20 Ohm 1% R15 pn-CRCW1206100 rc1206 CRCW1206100 OPEN R16 pn-CRCW12064990 rc1206 CRCW12064990 499 Ohm 1% R20 pn-CRCW1206111 rc1206 CRCW1206111 110 Ohm 1% R21 pn-CRCW1206111 rc1206 CRCW1206111 110 Ohm 1% R22 pn-CRCW1206111 rc1206 CRCW1206111 110 Ohm 1% R23 pn-CRCW1206111 rc1206 CRCW1206111 110 Ohm 1% R25 pn-CRCW12064990 rc1206 CRCW12064990 499 Ohm 1% R26 pn-CRCW12064990 rc1206 CRCW12064990 499 Ohm 1% R27 pn-res_4990 thd_2_4 res_4990 4.02 kOhm 1% R28 pn-Bourns3266 small_pot trim_pot 500 Ohm R29 pn-res_4990 thd_2_4 res_4990 4.02 kOhm 1% R50 pn-Bourns3266 small_pot trim_pot 500 Ohm R51 pn-res_124 thd_2_4 res_124 See Table R52 pn-CRCW1206241 rc1206 CRCW1206241 243 Ohm 1% R53 pn-res_649 thd_2_4 res_649 See Table R54 pn-res_499 thd_2_4 res_499 See Table R55 pn-CRCW1206241 rc1206 CRCW1206241 243 Ohm 1% R56 pn-res_909 thd_2_4 res_909 909 Ohm 1% R56 pn-res_909 thd_2_4 res_909 1.0k Ohm 1% R57 pn-CRCW1206241 rc1206 CRCW1206241 243 Ohm 1% R58 pn-res_715 thd_2_4 res_715 715 Ohm 1% R59 pn-CRCW1206121 rc1206 CRCW1206121 124 Ohm 1% R60 pn-res_357 thd_2_4 res_357 374 Ohm 1% R75 pn-316B471 dip16 316B471 470 Ohm Isolated R76 pn-316B471 dip16 316B471 470 Ohm Isolated R77 pn-110A560 sip10 110A560 56 Ohm Bussed R78 pn-110A560 sip10 110A560 56 Ohm Bussed R79 pn-110A560 sip10 110A560 56 Ohm Bussed R80 pn-110A560 sip10 110A560 56 Ohm Bussed Array Supply Setup vs A-Card Serial Number -------------------------------------------- Supply +5_Anl and +5_Dig DSub VClamp ----------------- ------------- ------------- Range Volts 4.750 - 5.250 3.500 - 4.000 2.100 - 3.600 R51 Ohms 1300 866 1330 R53 Ohms 1400 866 187 R54 Ohms 499 464 301 A-Card Serial No. 2, 3, 6, 7, 9 1, 5 4, 8 Cards installed in the Camera that was shipped 30-DEC-1997 M-Card M-Card M-Card A-Card Slot Function Array Range Serial Number ------ -------- ------------ ------------- J1 D-Sub 0:63 1 J2 V-Clmp 64:127 4 J3 Analog 128:191 3 or 2 J4 Digital 192:255 2 or 3