Datasheet

IOUTP
4:1
IOUTN
AGND
100 Ω
R
50 Ω
LOAD
100 Ω
S0518-01
IOUTP
1:1
IOUTN
AGND
50 Ω
R
50 Ω
LOAD
50 Ω
100 Ω
S0517-01
DAC3484
www.ti.com SLAS749C –MARCH 2011–REVISED AUGUST 2012
ANALOG CURRENT OUTPUTS
The DAC3484 can be easily configured to drive a doubly terminated 50 Ω cable using a properly selected RF
transformer. Figure 88 and Figure 89 show the 50 Ω doubly terminated transformer configuration with 1:1 and 4:1
impedance ratio, respectively. Note that the center tap of the primary input of the transformer has to be grounded
to enable a DC current flow. Applying a 20 mA full-scale output current would lead to a 0.5 Vpp for a 1:1
transformer and a 1 Vpp output for a 4:1 transformer. The low dc-impedance between IOUTP or IOUTN and the
transformer center tap sets the center of the ac-signal to GND, so the 1 Vpp output for the 4:1 transformer
results in an output between –0.5 V and +0.5 V.
Figure 88. Driving a Doubly terminated 50 Ω Cable Using a 1:1 Impedance Ratio Transformer
Figure 89. Driving a Doubly Terminated 50 Ω Cable Using a 4:1 Impedance Ratio Transformer
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