Texas Instruments THS5661A Evaluation Module THS5661EVM THS5661EVM 데이터 시트
제품 코드
THS5661EVM
External Clock
3.6.2 C542/C54xxDSK/Microprocessor Mode
A DSP subsystem such as the C54X DSPplus/C5410 DSK provides some advantage when evaluating the
DAC performance with signals, such as W-CDMA data points and arbitrary generated waveform data
points. The clock frequency, via the
DAC performance with signals, such as W-CDMA data points and arbitrary generated waveform data
points. The clock frequency, via the
’
C54x DSK adapter board, is set at 40 MHz.
3.6.3 Analog Output Circuits
The 1:1 RF transformer is used for impedance matching, dc isolation and interfacing between the
balanced differential CommsDAC outputs and an unbalanced single-ended output. The resistors R23,
R24, and R29 are used to form a network that reflects 50
balanced differential CommsDAC outputs and an unbalanced single-ended output. The resistors R23,
R24, and R29 are used to form a network that reflects 50
Ω
across the primary circuit (J6).
Potentiometer R14 is used to set the CommsDAC full-scale output current. With R14 value set equal to
1.9 k
1.9 k
Ω
, the full-scale current from the DAC is 20 mA.
A spectrum analyzer with 50-
Ω
input impedance is normally used to measure the performance of the DAC.
A 50-
Ω
coaxial cable is used to connect J6 output to the 50-
Ω
input of the spectrum analyzer. The
spectrum analyzer impedance is in parallel to the transformer 50-
Ω
reflected impedance across J6.
Therefore, the voltage at the input of the spectrum analyzer is 1/2 J6. If a larger voltage is required, use a
1:2 step up voltage ratio transformer to produce twice the voltage at J6. In addition set R23 to 200
1:2 step up voltage ratio transformer to produce twice the voltage at J6. In addition set R23 to 200
Ω
and
remove R24 and R29. R14 may require some adjustments.
A 1-V output will appear at J8 and J9 when IOUT1 and IOUT2 are terminated into 50-
Ω
external resistor
loads (output taken from J8 and J9 and W6 and W7 open). If 75-
Ω
external resistors are used the
maximum IOUT1/IOUT2 output current is 16 mA.
The THS3001 operates as a differential amplifier when: W9 is left opened, W8 pins 1 and 2 are connected
together, W6 position A is connected to IOUT1, and W7 position D is connected to IOUT2.
together, W6 position A is connected to IOUT1, and W7 position D is connected to IOUT2.
The THS3001 operates as an inverting amplifier under the following conditions: W9 is connected, R27 is
set to 0
set to 0
Ω
, W8 pins 1 and 2 are connected together, and the input is from either W6 position B or W7
position D. If the input is via W6 position B, the output at J7 is
–
1.2 V. If the input is via W7 position D, the
output will be
–
1.2 V.
The THS3001 operates as a noninverting amplifier when: W9 is opened, W8 pins 2 and 3 are connected
together, and the input is from either W6 position A or W7 position E. If the input is via W6 position A, the
output voltage is 2 V. If the input is taken via W7 position E, the output voltage at J7 is 2 V.
together, and the input is from either W6 position A or W7 position E. If the input is via W6 position A, the
output voltage is 2 V. If the input is taken via W7 position E, the output voltage at J7 is 2 V.
31
SLAU032C
–
February 2001
–
Revised April 2011
User Configurations
Copyright
©
2001
–
2011, Texas Instruments Incorporated