APPLICATION INFORMATION

Line Driver Amplifiers

f

=

c

1

2 R C

p

L

O

(1)

C

=

O

1

2 R f

p

L

c

(2)

C

O

C

O

V

OUT

GND

V

DD

V

/2

DD

Conventional

GND

V

DD

V

SS

DirectPath

DRV601

Single-supply Line Driver amplifiers typically require dc-blocking capacitors. The top drawing in Figure 13

illustrates the conventional Line Driver amplifier connection to the load and output signal.

DC blocking capacitors are often large in value. The line load (typical resistive values of 600

Ω to 10 kΩ)

combine with the dc blocking capacitors to form a high-pass filter. Equation 1 shows the relationship between the

values require large package sizes. Large package sizes consume PCB area, stand high above the PCB,

increase cost of assembly, and can reduce the fidelity of the audio output signal.

Figure 13. Amplifier Applications

The DirectPath™ amplifier architecture operates from a single supply but makes use of an internal charge pump

to provide a negative voltage rail. Combining the user provided positive rail and the negative rail generated by

the IC, the device operates in what is effectively a split supply mode. The output voltages are now centered at

zero volts with the capability to swing to the positive rail or negative rail. The DirectPath™ amplifier requires no

output dc blocking capacitors. The bottom block diagram and waveform of Figure 13 illustrate the

ground-referenced Line Driver architecture. This is the architecture of the DRV601.

8

Copyright © 2008, Texas Instruments Incorporated

Product Folder Link(s): DRV601