Texas Instruments DAC5674 EVM, User Manual

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Circuit Function
3-3 Circuit Description
Table 3−2. Input Connector J8
J8 Pin Description J8 Pin Description J8 Pin Description
1 CMOS data bit 13 (MSB) 15 CMOS data bit 6 29 Reset
2 GND 16 GND 30 GND
3 CMOS data bit 12 17 CMOS data bit 5 31
4 GND 18 GND 32 GND
5 CMOS data bit 11 19 CMOS data bit 4 33
6 GND 20 GND 34 GND
7 CMOS data bit 10 21 CMOS data bit 3 35
8 GND 22 GND 36 GND
9 CMOS data bit 9 23 CMOS data bit 2 37
10 GND 24 GND 38 GND
11 CMOS data bit 8 25 CMOS data bit 1 39 SCLK_IN
12 GND 26 GND 40 GND
13 CMOS data bit 7 27 CMOS data bit 0 (LSB)
14 GND 28 GND
3.1.3 Output Data
The DAC5674 EVM can be configured to drive a doubly terminated 50-
Ω
cable
or provide unbuffered differential outputs.
3.1.3.1 Transformer Coupled Signal Output
The factory-set configuration of the demonstration board provides the user
with a single-ended output signal at SMA connector J7. The DAC5674 is
configured to drive a doubly terminated 50-
Ω
cable using a 1:1 impedance
ratio transformer, a 100-
Ω
terminating resistor R2, and the center tap of T1
connected to ground per Table 3−3. When using a 4:1 impedance ratio
transformer, configure the EVM per Table 3−3. The common mode input
voltage of T1 can be adjusted by using the resistor divider network R5 and R6.
Table 3−3. Transformer Output Configuration
Configuration Components Installed
†
Components Not Installed
1:1 Impedance ratio transfomer R2, R3, R4, R6, C22, T1 (1:1) R5, R7, R8, C20, C21
4:1 Impedance ratio transfomer R3 (100), R4 (100), R6, C22,
T1 (4:1) R2, R5, R7, R8, C20, C21
†
All component values are per the schematic except where shown in parenthesis.
3.1.3.2 Unbuffered Differential Output
To provide unbuffered differential outputs, the EVM must be configured as
follows: remove R2, C20, C21, and T1; Install R3, R4, R7, R8, J1 and J6.