DRV134 Datasheet, PDF (15/30 Pages) Burr-Brown (TI) – AUDIO BALANCED LINE DRIVERS

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9 Application and Implementation
DRV134, DRV135
SBOS094B – JANUARY 1998 – REVISED DECEMBER 2014
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
Decoupling capacitors placed close to the device pins are strongly recommended in applications with noisy or
high impedance power supplies.
For best system performance, it is recommended that a high input-impedance difference amplifier be used as the
receiver. Used with the INA134 (G = 0 dB) or the INA137 (G = ±6 dB) differential line receivers, the DRV134
forms a complete solution for driving and receiving audio signals, replacing input and output coupling
transformers commonly used in professional audio systems (Figure 29). When used with the INA137 (G = –6 dB)
overall system gain is unity.
9.2 Typical Application
9.2.1 Cable Driving Application
The DRV134 is capable of driving large signals into 600-Ω loads over long cables. Low impedance shielded
audio cables such as the standard Belden 8451 or 9452 (or similar) are recommended, especially in applications
where long cable lengths are required.
For applications with large dc cable offset errors, a 10-µF electrolytic nonpolarized blocking capacitor at each
sense pin is recommended as shown in Figure 29.
DRIVER
DRV134
DRV135
4
V_IN
A1
Gnd ³
RECEIVER
50Ω ₈
A2
10µF⁽¹⁾
7
+V_O
BALANCED
CABLE PAIR
–V_O
2
5
10kΩ
6
V_O
10µF⁽¹⁾
2
50Ω ₁
–V_O
A3
3
+V_O
1
INA134, INA137
All resistors 30kΩ unless otherwise indicated.
10kΩ
INA134 (G = 1): V_O = 2V_IN
INA137 (G = 1/2): V_O = V_IN
Figure 29. Complete Audio Driver and Receiver Circuit
9.2.1.1 Design Requirements
Consider a design with the goal of differentially transmitting a single ended signal of up to 22.2 dBu through 500
ft of cable with no load at the receiving side. The signal at the end of the cable should have no more than 0.002
percent of total harmonic distortion plus noise (THD+N) at 10 kHz and less than 0.0005 percent of THD+N for
frequencies between 20 Hz and 1 kHz.
The system is required to put out a single ended signal 0 dB with respect to the input signal and accommodate
inputs with peak to RMS ratios of up to 1.5 for the maximum 22.2 dBu range established above.
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