Datasheet

IOUTP
4 : 1
50 ?
R
LOAD
100 ?
100 ?
IOUTN
AVDD (3.3V)
AVDD (3.3V)
IOUTP
1 : 1
IOUTN
50 ?
R
LOAD
100 ?
50 ?
50 ?
AVDD (3.3V)
AVDD (3.3V)
DAC3152
DAC3162
www.ti.com SLAS736D –NOVEMBER 2010–REVISED AUGUST 2012
ANALOG CURRENT OUTPUTS
The DAC outputs can be easily configured to drive a doubly terminated 50-Ω cable using a properly selected RF
transformer. Figure 41 and Figure 42 show the 50-Ω doubly terminated transformer configuration with 1:1 and 4:1
impedance ratios, respectively. Note that the center tap of the primary input of the transformer must be
connected to AVDD to enable a dc current flow. Applying a 20-mA full-scale output current leads to a 0.5-Vpp
output 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 AVDD, so the 1-Vpp output for the 4:1
transformer results in an output between AVDD – 0.5 V and AVDD + 0.5 V.
Figure 41. Driving a Doubly Terminated 50-Ω Cable Using a 1:1 Impedance-Ratio Transformer
Figure 42. Driving a Doubly Terminated 50-Ω Cable Using a 4:1 Impedance-Ratio Transformer
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