Texas Instruments DAC5668, Руководство пользователя

Страница: 10 / 36

EXTIO
FS
V
IOUT = 16
R91
æ ö
´ ç
÷
è ø
DAC5668/88/89 EVM Software
www.ti.com
The DAC5668/88/89EVM also includes a pi pad network on the modulator output to provide some
matching or filtering, if desired. In its default state, the pad is not used and a series capacitor is used on
the RF output.
4.8 Reference Operation
The DAC full-scale output current is set by applying an external resistor (R91) between the BIASJ pin of
the device and ground. The full-scale output current can be adjusted from 20 mA down to 2 mA by varying
this resistor. The full-scale output current, IOUTFS, is defined as follows:
(1)
where V
EXTIO
is the voltage at pin EXTIO. This voltage is 1.2 V when using the internally provided bandgap
reference voltage source. The internal reference can be disabled and overridden by an external reference
by connecting a voltage source to EXTIO and connecting EXTLO to +3.3 Vdc (J5 EXTLO connected
between pins 2 and 3). The specified range for external reference voltages must be observed.
5 DAC5668/88/89 EVM Software
The EVM Control Software is started by accessing the Windows Start → All Programs → Texas
Instruments DACs cascading menus. The DAC5668 and the DAC5688 share the same EVM software,
and the DAC5689 has a stand-alone EVM software.
The DAC EVM application allows users to:
• Configure the DAC and CDCM7005 registers.
• Save and load register settings using text files.
• Visualize the data path through the DAC.
5.1 Software Description
The software has five main settings that allow you to modify the functionality of the active panels. You can
switch between these settings by selecting one of the Menu items described in
Table 6 .
10 DAC5668/88/89EVM SLAU241A – June 2008 – Revised March 2010
Submit Documentation Feedback
Copyright © 2008–2010, Texas Instruments Incorporated