Architecture description – Sundance SMT377 User Manual
Page 10
Version 1.1
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SMT377 User Manual
Architecture description.
The module consists of two DAC7634-quad digital to analogue converters (DAC).
They are serially connected to a Xilinx Virtex-II FPGA, which is responsible for
transferring the output samples to the DACs.
DAC output range is +/-2.5V. Output channels (1 to 8; J5-J12) are either available
directly from the DAC chips (NA) or a buffered (A) output – via output opamps
(Selection on hardware – to be specified on order). The selection is made via dual-
position resistors on the board.
The Xilinx Virtex-II FPGA is configured from a ComPort – 3 or 4 (3 by default) – via a
CPLD. FPGA (re)configuration is allowed only prior to a module (TIM) reset or at
anytime using the JTAG connector (J2) and a Xilinx programming cable (Parallel III
or IV).
The on-board memory can be externally accessed. Some waveform patterns can be
stored, read back and converted into analogue signals – Pattern generator mode.
DAC output samples are input to the FPGA from one of following sources: Comport
or SHB. The current default firmware implement only the Comport option. DAC
samples can by routed to the memory for Pattern Generator mode or straight to the
DACs for Direct Transfer mode
DAC7634, 16 bit, quad voltage output Digital-to-Analog converter.
The DAC7634 is a 16-bit, quad voltage output, Digital-to-Analog Converter with
guaranteed 15-bit monotonic performance over the specified temperature range. It
accepts 24-bit serial input data, has double-buffered DAC input logic (allowing
simultaneous update of all DACs), and provides a serial data output for daisy
chaining multiple DACs. Programmable asynchronous reset clears all registers to a
mid-scale code of 8000H or to a zero-scale of 0000H.
The DAC7634 is a low power device (10mW) with a 10
µ
s settling time to 0.003%.
It operates from a +5 Volts and –5 Volts supplies and +2.5 Volts and –2.5 Volts as
reference voltages, which means that the output range is –2.5 to +2.5 Volts.
The following link gives more details about the DAC7634: