3
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1.0 Introduction
The DAC121C08XEB Design Kit (consisting of the
DAC Evaluation Board and this User's Guide) is
designed to ease evaluation and
design-in of National Semiconductor’s
DAC121C081/DAC121C085 family of Digital-to-
Analog Converters (DACs). The Micro-Power
DACs feature Rail-to-Rail Output and an I
2
C-
Compatible interface. This User’s Guide supports
all three resolutions of the DAC family. The
evaluation board comes with the full-featured
MSOP-8 version of the DAC. For the 12-bit
resolution, the DAC121C085 is used. For the 10-
bit resolution, the DAC101C085 is used. For the
8-bit resolution, the DAC081C085 is used. All the
devices in the family (DAC121C085,
DAC101C085, and DAC081C085) will be referred
to as the DAC121C085 in this document.
The evaluation board can be used in either of two
modes. In the Stand-Alone mode, suitable test
equipment, such as a pattern generator and signal
analyzer, can be used with the board to evaluate
the DAC121C085 performance.
In the Computer mode, data capture and
evaluation is simplified by connecting this board to
National Semiconductor’s Data Capture Board
(order number WAVEVSN BRD 4.4). The Data
Capture (WV4) Board is connected to a personal
computer running WaveVision software through a
USB port. The WaveVision4 software runs on
Microsoft Windows, and the latest version can be
downloaded from the web at
http://www.national.com/adc
.
Note: WaveVision Software version 4.4 or later is
required to evaluate this part with the WV4
Evaluation System.
The WaveVision software allows the user to drive
the DAC121C085 with a variety of preset
waveforms and custom waveforms. The software
also allows the user to configure the I
2
C serial
Interface.
Data transmitted to the DAC121C085, via the
I
2
C interface, is converted to an analog waveform
by U1, the DAC121C085.
Figure 1: Component and Test Point Locations
J3
WV4 Connector
JP10
3P3V Select
JP9
V
A
Select
JP4
Output Load
JP5
Add Select
U1
DAC121C085
J1
WV4S
Connector
J2
V
A
Input
JP7
V
REF
Select
J4
V
OUT
