Description of the output part

TDA7501

14/29

Figure 11.

Level diagram.

4.2

Speaker (linedriver) outputs

The Speaker outputs can be configured in three different operating modes:

1.

- Internal reference mode with 0dB output gain,

2.

- External reference mode with 0dB output gain

3.

- External reference mode with 6dB output gain

Basically, in the internalreference mode the linedriver amplifier acts as a buffer with 0dB gain

regardless of the output gain programmed by bit D0. Since the buffer tracks the internal

generated reference, the OUTPUTREF pin may be left floating.

In the external reference mode the linedriver amplifiers reference tracks the voltage present

at the OUTPUTREF pin. This reference does not necessary have to be external to the

device, it can also be generated by invoking the VCC/2 divider inside the TDA7501 (bit

D1/6). In practice, the term external reference implied that the OUTPUTREF pin at least has

to connect to an external capacitor. In the external reference mode, an additional gain of

For the programming of output gain and reference selection see the programming section.

Figure 12.

Speaker (Linedriver) outputs simplified

INPUT GAIN

0..15dB

1dB STEP

CODEC

INTERFACE

TDA7500

VOLUME

+15

LEVEL

SELECT

..

-79dB

OUTPUT

LINEDRIVERS

0/+6dB STEP

INPUT PART

TDA7501

OUTPUT PART

IN

OUT

2Vrms

4.15Vdc

2Vrms

4.15Vdc

0.8Vrms

1.65Vdc

0.9Vrms

1.65Vdc

2Vrms

4.15Vdc

+6dB or

+12dB

GAIN

2Vrms (typ)

4.15Vdc

2Vrms

4.15Vdc

or

4Vrms

6Vdc

D00AU1205

D0/6

0dB

buffer

6dB

6dB

6dB

6dB

OUTPUTREF

SPKROUT

from VOLUME-STAGE

2Vrms

4.15Vdc

2RR3R

2RR3R

D0/6

+

-

D1/6

D1/6

D00AU1207