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5
EVM Overview
5.1
Features
5.2
Power Requirements
EVM Overview
This section gives a general overview of the DAC7741 evaluation module (EVM), and describes some of
the factors that must be considered in using this module.
This EVM features the DAC7741 digital-to-analog converter. The DAC7741 EVM is a simple evaluation
module designed for a quick and easy way to evaluate the functionality of the high resolution,
single-channel, and parallel input DAC. This EVM features a parallel interface to communicate to any host
processor base system
The following sections describe the power requirements of this EVM.
5.2.1
Supply Voltage
The dc power supply requirement for the digital section of this EVM is typically 5 V connected to the J12-3
or via J6-10 terminal (when plugged in with another EVM board or interface card) and is referenced to
ground through the J12-2 and J6-5 terminal. The dc power supply requirement for the analog section (V
CC
and V
SS
) of this EVM range from 15.75 V to -15.75 V maximum and connects through J11-3 and J11-1 or
through J6-1 and J6-2 terminals and is referenced to analog ground through J11-2, J12-2, and J6-6
terminals.
The dc source of
±
15 V supply required to provide the rails for the external output operational amplifier is
derived from V
CC
and V
SS
as described above. The output operational amplifier, U2, is used for output
signal conditioning or boost capacitive load drive and for other output modes of application.
CAUTION
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.
5.2.2
Reference Voltage
Although the DAC7741 has a built-in 10-V voltage 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 J2-20 or J4-20 terminals via jumper W31, to allow the
user to connect another external reference source if the onboard reference circuit is not desired. The
external voltage reference should not exceed 10-V dc.
The REF102 precision reference derives its supply power of 15 V through J11 or J6 terminal as described
earlier regarding supply voltages.
The DAC7741 has a REFEN pin to enable the internal reference circuit or disable it and select an external
reference source. The REFEN pin can be hardware-driven through W2 jumper. Likewise, it can also be
software-driven through J3-17 terminal via W2 jumper by shorting pins 1 and 2. The REF
OUT
pin of the
DAC7741 must be connected to the REF
IN
pin to use the internal voltage reference. This is done through
the W3 jumper by shorting pins 1 and 2. Shorting pins 2 and 3 of W3 selects the external voltage
reference source.
DAC7741EVM
SLAU093A – October 2002 – Revised May 2005
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