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EVM Overview
CAUTION
To avoid potential damage to the EVM board, make sure 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
The DAC8881 requires an external reference source to set the DAC operating voltage output range.
Applying the desired voltage in the range of 1.25V to AV
DD
to the V
REF
H pin sets the positive range of the
DAC8881 output. Applying the desired voltage in the range of –0.2V to +0.2V to the V
REF
L pin sets the
negative range of the DAC8881 output, although the V
REF
L pin should nominally be set to 0V. The
voltages applied to the V
REF
H and V
REF
L pins set the DAC8881 full output voltage swing.
For optimum performance, the DAC8881 supports a set Kelvin connection to the external reference via
the V
REFH
F and V
REFH
S pins as well as V
REFL
F and V
REFL
S pins. This optional reference configuration
minimizes internal errors caused by the changing reference current and its associated circuit impedances.
A +5V precision voltage reference is provided for the external reference source of the DAC through
REF02, U3. The power supply for the reference device, U3, is selectable between V
CC
and +5VA via the
W11 jumper to ensure that the correct voltage range of U3 can be set. As mentioned earlier, a device from
the family of REF50xx reference devices can be easily selected and the one installed on the EVM can be
replaced to provide the desired voltage range that is required for evaluation of the DAC8881.
The reference voltages, V
REF
H and V
REF
L, are selectable via jumpers W8 and W4. When shorting pins 1
and 2 of both jumpers, the on-board +5V reference via U3 is selected. Shorting pins 2 and 3 of both
jumpers selects the reference voltages that are applied via J4 pins 18 and 20 respectively. These voltages
normally come from the host platform that is interfaced with the DAC8881EVM.
The test points TP1 and TP8 are also provided to allow the user to connect another external reference
source if the on-board reference circuit is not desired. The external voltage reference should not exceed
the applied power supplies (AV
DD
and DV
DD
) of the DAC under test.
CAUTION
When applying an external voltage reference through TP8 or J4-20, make sure
that it does not exceed the applied AV
DD
. Otherwise, this can permanently
damage the DAC8881, U1, device under test.
1.3
EVM Basic Functions
This EVM is designed primarily as a functional evaluation platform to test certain functional characteristics
of the DAC8881 digital-to-analog converter. Functional evaluation of the installed DAC device can be
accomplished with the use of any microprocessor, DSP, or signal/waveform generator.
The headers J2 (top side) and P2 (bottom side) are pass-through connectors provided to allow the control
signals and data required to interface a host processor or waveform generator to the DAC8881 EVM using
a custom built cable.
An adapter interface card (5-6k adapter interface card) is also available to fit and mate with TI’s C5000
and C6000 DSP Starter Kit (DSK). This card alleviates the problems involved in building a custom cable.
In addition, the Precision Analog Application group of Texas Instruments has other interface boards that
are designed to connect to and interface with this EVM as well. For more details or information regarding
the 5-6k adapter interface board or the other interface platforms, call Texas Instruments Inc. or send an
email to
.
3
SLAU257A – September 2008 – Revised November 2009
DAC8881 Evaluation Module
Copyright © 2008–2009, Texas Instruments Incorporated