C

1

2pR

1

2pR

1

2

3

4

5

6

7

8

9

10

15

14

13

12

11

20

19

18

17

16

Top View

LEFTINM

LEFTINP

GND

RIGHTINP

RIGHTINM

HPRIGHT

VDD

GND

HPLEFT

CPVSS

0.47uF

0.47uF

0.47uF

0.47uF

2.2KQ

1uF

1uF

1uF

1uF

TPA6133A2

www.ti.com

SLOS821 – JUNE 2013

APPLICATION INFORMATION

SIMPLIFIED APPLICATIONS CIRCUIT

Headphone Amplifiers

Single-supply headphone amplifiers typically require dc-blocking capacitors. The capacitors are required because

most headphone amplifiers have a dc bias on the outputs pin. If the dc bias is not removed, the output signal is

severely clipped, and large amounts of dc current rush through the headphones, potentially damaging them. The

top drawing in Figure 19 illustrates the conventional headphone amplifier connection to the headphone jack and

output signal.

DC blocking capacitors are often large in value. The headphone speakers (typical resistive values of 16

Ω or 32

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

(1)

(2)

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.

Copyright © 2013, Texas Instruments Incorporated

9

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