Features
1-2
1.1
Features
This EVM features the DAC7731 digital - to - analog converter. The
DAC7731EVM is a simple evaluation module designed for a quick and easy
way to evaluate the functionality and performance of the high resolution,
single-channel, and serial input DAC. This EVM features a serial interface to
communicate with any host microprocessor or TI DSP (with SPI capability)
base system.
1.2
Power Requirements
The following sections describe the power requirements of the EVM.
1.2.1
Supply Voltage
The dc power-supply requirement for the digital section of the EVM is typically
5 V connected to the J3- 1 or via J6- 10 terminal (when plugged in with another
EVM board or interface card) and is referenced to ground through the J3 - 2
and J6 - 5 terminal. The dc power-supply requirement for the analog section
(V
CC
and V
SS
) of this EVM range is from 15.75 V to - 15.75 V maximum. The
analog section connects through J1 - 3 and J1- 1 respectively, or through J6- 1
and J6 - 2 terminals and are referenced to analog ground through J1 - 2 and
J6 - 6 terminals.
The V
CC
supply source is also used to provide the positive rail of the external
output op amp while the negative rail can be selected between V
SS
and AGND
via the W5 jumper. The external op amp is installed as an option to provide
output signal conditioning or boost capacitive load drive and for other output
mode requirements.
To avoid potential damage to the EVM board, make sure that the
correct cables are connected to their respective terminals as
labeled on the EVM board.
Stresses above the maximum listed voltage ratings may cause
permanent damage to the device.
1.2.2
Reference Voltage
Although the DAC7731 has a built-in 10-V reference, an external reference
circuit is provided in the EVM board. The external reference circuit can be
isolated if the internal reference voltage is selected.
The 10-V precision voltage reference is provided to supply the external voltage
reference for the DAC through REF102, U3, via jumper W4 by shorting
pins 1 and 2. An adjustable 100-k
Ω
potentiometer, R11, is installed in series
with 20 k
Ω
, R10, to allow the user to adjust the reference voltage to its desired
settings. TP1 and TP2 are also provided, as well as J4 - 20, to allow the user
to connect other external reference source if the onboard reference circuit is
not desired. The external voltage reference must not exceed 10 V dc.
