Texas Instruments DAC7631EVM Evaluation Module DAC7631EVM DAC7631EVM Datenbogen
Produktcode
DAC7631EVM
www.ti.com
7.5
Digitally Programmable Current Source Application
EVM Operation
Table 4. Unity Gain Output Jumper Settings
Reference
Jumper Position
Function
W15
OPEN
OPEN
Disconnect the inverting input of operational amplifier, U2, from AGND.
W5
2-3
1-2
Negative rail of operational amplifier is tied to AGND or powered by V
SS
.
7.4.2
Output Gain of Two
shows the proper jumper settings of the EVM for the 2
×
gain output of the DAC.
Table 5. Gain of Two Output Jumper Settings
Reference
Jumper Position
Function
Unipolar
Bipolar
Inverting input of the output operation amplifier, U2, is connected to AGND to set for a gain
W15
CLOSED
CLOSED
of 2.
Supplies power, V
SS
, to the negative rail of operation amplifier, U2, for bipolar supply
W5
2-3
1-2
mode, or ties it to AGND for unipolar supply mode.
7.4.3
Output Gain of Five With DAC V
OUT
Inverted
Table 6. Jumper Settings for a Gain of Five With Inverted Output
Reference
Jumper Position
Function
Unipolar
Bipolar
Output of DAC is inverted with a gain of 5. Watch for clipping in unipolar mode due
J5
1-2 & 3-4
1-2 & 3-4
to operational amplifier headroom issue.
W15
OPEN
OPEN
Disconnect the inverting input of operational amplifier, U2, from AGND.
Supplies power, V
SS
, to the negative rail of operational amplifier, U2, for bipolar
W5
2-3
1-2
supply mode, or ties it to AGND for unipolar supply mode.
A digitally programmable, unidirectional current-source circuit is added for the convenience of users who
find the need for this type of application. Basically, the output of the DAC7631 can be connected to either
the base of transistor, Q1 or the current input pin of the XTR115, U4A, via jumper W6. The sense pin of
the DAC7631 should be connected to the emitter side of transistor Q1 via jumper W9, if used. If the
XTR115, U4A, is selected to do this operation, the sense pin of the DAC7631 should be tied back to the
VOUT pin via jumper W8. The jumper, W7, must be ensured in the position of 2-3 for the REF1 to drive
the reference voltage of the DAC7631. A simple configuration of this setup is shown in
find the need for this type of application. Basically, the output of the DAC7631 can be connected to either
the base of transistor, Q1 or the current input pin of the XTR115, U4A, via jumper W6. The sense pin of
the DAC7631 should be connected to the emitter side of transistor Q1 via jumper W9, if used. If the
XTR115, U4A, is selected to do this operation, the sense pin of the DAC7631 should be tied back to the
VOUT pin via jumper W8. The jumper, W7, must be ensured in the position of 2-3 for the REF1 to drive
the reference voltage of the DAC7631. A simple configuration of this setup is shown in
To operate the DAC7631 for the digitally programmable, unidirectional current-source application, the
DAC7631 must be configured for the unipolar mode of operation. For a 4-mA to 20-mA operation, the
VREFL input must be set to accept 500 mV, which can be externally provided through the –REFin input
via J4-18. The jumper, W11, should be positioned to 2-3 to pass the voltage through.
DAC7631 must be configured for the unipolar mode of operation. For a 4-mA to 20-mA operation, the
VREFL input must be set to accept 500 mV, which can be externally provided through the –REFin input
via J4-18. The jumper, W11, should be positioned to 2-3 to pass the voltage through.
The VREFH can take its input from REF1 via jumpers, W7 and W10.
See
for the setup configuration.
12
SLAU148 – January 2005
DAC7631EVM