---+!! Cryo Electronics Design
This is a work area for design of electronics for controlling the cryogenics in bolometer receivers.
To do list:
- Anton:
- look for 5V --> 24 V DC/DC converter or cheap isolated 36V power supply.
- Design front panel with Peter D.
- Shah's AdcCommandSequence
Matt's notes on Thermometry Sensors
RTD readout
- need a minimum of 6 RTDs (ultrahead/stage, interhead/stage, hex, + 1 extra)
- allow for arbitrary bias wave functions (normally we'll use DC, sine wave, or square wave).
- Lakeshore cernox 1010, 0.2K 1573 ohms, 300K 32.3 ohms
- SRS: provides 3uV - 30mV voltage drive ( current drive 1-1000 uA)
Diode Readout
- 300K lakeshore diode produces 0.584V @ 10 uA = 58K, at 1K produces 1.797V @ 10 uA = 180K
- SRS provides 2V sense max, +-0.2%, 0.5 mV LSB
- need constant current output of 10 uA +-0.1%. We could adjust this value digitally or with analog feedback.
Heater drive
- need 8 heaters total (2 wire connection per heater)
- 20V at a max of 100 mA. Must be able to completely DISABLE the output.
- put current through 10 ohm resistor and measure voltage across it.
- method of supply
- could use a single ended transistor like the squid heater.
- or a linear voltage regulator (single ended - unless we can find an isolated one, but probably not without having it switch)
- or a differential speaker driver.
- AD815 Differential driver, can supply up to 500mA. Connect V+ to 24V, in- to GND thru 100 ohms, and V- to GND. Set a gain of 10. Problem is there is no disable.
- see http://www.national.com/an/AN/AN-1515.pdf for a national semiconductor applications note on a Howland Current Pump.
FPGA Resources
- Avnet V4-FX12 mini-module ($250) provides FPGA, ethernet, 64 MByte DDR, 8Mb platform flash (for program), 4 MByte flash.
- jtag program, need pins on motherboard
- fpga uses on-board 100 MHz clock. Remove this, and bring in 25 MHz from board to FPGA pin.
- PHY uses on-board 25 MHz (this is a problem), probably can remove this, and bring in the 25MHz with a jumper wire.
- requires +3.3V, 2.5V, 1.2V from motherboard.
- dimensions, 30 mm wide, 65.5mm long. RJ45 protrudes from front by 5mm. Total height is RJ45 + 0.21"
- connects to motherboard mating to 64 pin samtec CLT-132-02-L-D (this is the MB connector p/n)
front panel (6U = 9 inches)
- space for FPGA mini-module with RJ45 takes 30mm = 1.2"
- RJ45 serial (2 RS485, 2 LVDS)
- rectangular cutout for LEDs
- two hddb44
This topic: CryoElectronics
> DigitalFMux > CryoElectronics
Topic revision: r17 - 2010-05-04 - WinterlandUser