Texas Instruments DAC7741 Evaluation Module DAC7741EVM DAC7741EVM 데이터 시트
제품 코드
DAC7741EVM
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9.2
Host Processor Operations
EVM Operation
The host processor basically drives the DAC; so, the DAC proper operation depends on the successful
configuration between the host processor and the EVM board. In addition, a properly written code is also
required to operate the DAC.
configuration between the host processor and the EVM board. In addition, a properly written code is also
required to operate the DAC.
A custom cable can be made specific to the host interface platform. The EVM allows interfacing to the
host processor through J3 header connector for the control signals, and J1 header connector for the data
input. An interface adapter card for a specific DSP starter kits or an HPA449 platform is also available as
mentioned in section 1 of this manual.
host processor through J3 header connector for the control signals, and J1 header connector for the data
input. An interface adapter card for a specific DSP starter kits or an HPA449 platform is also available as
mentioned in section 1 of this manual.
The EVM includes an optional signal conditioning circuit for the DAC output through an external
operational amplifier, U2. This is set to a unity gain configuration by default. Regardless, the raw output of
the DAC can be probed through W13 pin 2 so that it can be compared with the output of U2, if necessary.
The output terminals J2 and J4 are provided to monitor the desired output of the DAC by shorting the
respective pins of W13 and selecting the position of W30.
operational amplifier, U2. This is set to a unity gain configuration by default. Regardless, the raw output of
the DAC can be probed through W13 pin 2 so that it can be compared with the output of U2, if necessary.
The output terminals J2 and J4 are provided to monitor the desired output of the DAC by shorting the
respective pins of W13 and selecting the position of W30.
The following sections describe the different configurations of the output amplifier, U2.
9.2.1
Unity Gain Output
The buffered output configuration is used to prevent loading the DAC7741 and should closely match the
raw output of the DAC with maybe some slight distortion because of the feedback resistor and capacitor.
The user can tailor the feedback circuit to closely match the desired wave shape by simply desoldering R6
and C12 and replacing them with the desired values. If desired, the user can simply delete R6 and C12
altogether, and solder a 0-
raw output of the DAC with maybe some slight distortion because of the feedback resistor and capacitor.
The user can tailor the feedback circuit to closely match the desired wave shape by simply desoldering R6
and C12 and replacing them with the desired values. If desired, the user can simply delete R6 and C12
altogether, and solder a 0-
Ω
resistor in place of R6.
shows the jumper setting for the unity gain configuration of the DAC external output buffer in
unipolar or bipolar mode.
Table 3. Unity Gain Output Jumper Settings
Jumper Setting
Reference
Function
Unipoar
Bipolar
W5
2-3
1-2
Supplies the voltage for the negative rail of the operational amplifier.
W13
3-4
3-4
DAC output is sent to the output terminals.
W14
Open
Open
exREFin is disconnected from the negative input of the operational amplifier.
W15
Open
Open
Disconnect negative input of the operational amplifier from GND
DAC7741EVM
14
SLAU093A – October 2002 – Revised May 2005