HELLORADIO.RU — интернет-магазин средств связи

CEDAC20 - precise analog and digital controller

CEDAC20 - precise analog and digital controller

CEDAC20 device is euromechanical version of CDAC20. Besides of mentioned this version hasn't internal connection of DAC output with 6th input of ADC. It provides an additional ADC input to user. All the rest parameters are identical for both versions and these devices have the single description. The reason for designing of euromechanical version is the following. At the time our laboratory is developing a power supply for main magnets of VEPP-2000 installation. This power supply must provide 10KA output current with high stability (0,01% and better). All control electronics for this power supply is implementing in euromecanics.

CEDAC20 device is intended for control of precise (0,01% or better) controlled power supplies. It may be used as general purpose device with precise DAC and 5-channel precise ADC on-board. The device has optoisolated input and output registers on-board. It gives an opportunity to build simple systems with the single devices. You can read a detail description (29-apr-2003) of device in pdf-file.
The device consist of:

- 1-channel 20-bits bipolar DAC;

- 5-channels ADC;
- 8-channel optoisolated output register;
- 8-channel optoisolated input register;
- CANBUS interface for communication with control computer;
- embedded microcontroller.

    An user can use CEDAC20 both precise general purpose digital-to-analog converter and  functional generator. An embedded microcontroller may store up to 8 files which describes changing output voltage in time. Embedded processor provides linear interpolation of output voltage between characteristic points. All devices in network or programmable group of devices may be started by single broadcast message. 
    6-channels ADC design is based on delta-sigma ADC chip and analog multiplexers. Actually the device have 8 input channels and all of them are identical for programmer. But, three channels have on-board connections. 6th and 7th channels connected to precise reference source and "zero". These connections are used by microprocessor to implement procedure of "system calibration" which highly improves accuracy of ADC. An embedded microprocessor provides multichannel (from 1 up to 8) measurements or fast measurements of single channel. Measured values may be sent to a control computer or may be stored in on-board memory. Stored values may be sent to a control computer after special request from network. Measurements of all devices in network or programmable group of devices may be started or breaked by single broadcast message. 
    An analog part of device is galvanically isolated from digital part. 


Parameters of CEDAC20:
- resolution of DAC - 20 bits and sign;
- accuracy of DAC - 0,01%;
- resolution of ADC - 24 bits;
- accuracy of ADC - 0,003%;
- input range of ADC - 10V;
- output range od DAC - 10V;
- channels of output register  8;
- channels of input register   8

Additionally You can read some paper, for example here.