Texas Instruments DAC7741 Evaluation Module DAC7741EVM DAC7741EVM 데이터 시트
제품 코드
DAC7741EVM
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EVM Operation
9.2.2
Output Gain of Two
This configuration allows the DAC output with a gain of two but is limited to the effective rails of the
operational amplifier. When the DAC7741 is configured to operate in bipolar mode, the DAC output must
be within the range of 12 V
operational amplifier. When the DAC7741 is configured to operate in bipolar mode, the DAC output must
be within the range of 12 V
PP
or less. Anywhere above the range of 12 V
PP
clips the output of the
operational amplifier. Likewise, when operating the DAC in unipolar mode, the DAC output must not
exceed 6 V
exceed 6 V
PP
.
shows the proper jumper settings of the EVM for the 2x gain output of the DAC.
Table 4. Gain of Two Output Jumper Settings
Reference
Jumper Setting
Function
1-2 (Bipolar)
Negative rail of the operational amplifier tied to -15 V for bipolar operation or
W5
2-3 (Unipolar)
AGND for unipolar operation.
W13
3-4
Amplified output of DAC is sent to the output terminal.
W14
Open
Disconnect exREFin from negative input of the operational amplifier.
W15
Open
Configures the operational amplifier for a 2x gain output.
9.2.3
Capacitive Load Drive
Another output configuration option is to drive a wide range of capacitive load requirement. However, all
operational amplifiers under certain conditions may become unstable depending on the operational
amplifier configuration, gain, and load value. These are just few factors that can affect operational
amplifiers stability performance and should be considered when implementing.
operational amplifiers under certain conditions may become unstable depending on the operational
amplifier configuration, gain, and load value. These are just few factors that can affect operational
amplifiers stability performance and should be considered when implementing.
In unity gain, the OPA627 operational amplifier, U2, performs well with large capacitive loads. Increasing
the gain enhances the amplifier’s ability to drive even more capacitance, and by adding a load resistor
would even improve the capacitive load drive capability.
the gain enhances the amplifier’s ability to drive even more capacitance, and by adding a load resistor
would even improve the capacitive load drive capability.
shows the jumper setting configuration for a capacitive load drive.
Table 5. Capacitive Load Drive Output Jumper Settings
Reference
Jumper Setting
Function
1-2 (Bipolar)
Negative rail of the operational amplifier tied to -15 V for bipolar operation or AGND for
W5
2-3 (Unipolar)
unipolar operation.
W13
3-4
Capacitive load drive output of DAC is channeled to the output terminals
W14
Open
Disconnect exREFin from negative input of the operational amplifier.
W15
Open
Disconnect R12
(1)
(1)
If there is a need to incrementally adjust the capacitive load output, replace R12 with a capacitor with the desired capacitance
value and close W15.
value and close W15.
DAC7741EVM
SLAU093A – October 2002 – Revised May 2005
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