P

A

ASP

AP8111

4 Pin Configuration

1

2

3

4

5

6

7

8

9

10

11

12

28

27

26

25

24

23

22

21

20

19

18

17

LOUT

LIN

VREF

CB1A

CB1B

CB1

GND

CB2B

CB2A

CB2

BYPASS

COM PI

CL1

FOUT

COM PC2

VCC

COM PC1

CB3B

CB3A

CB3

CL2B

CL2A

RIN

ROUT

1

13

14

16

15

TBGAIN

NC

NC

NC

5 Operating Modes

The chip can be configured in 3 modes of operations – Power down mode, bypass mode, TruBass mode.

In power down mode, the chip is power down and consumed minimal current.

In bypass mode, line in audio signal is pass directly to the output.

In TruBass mode, line in audio signal is enhanced with the TruBass algorithm.

The Bypass pin (pin 11) is used to select the operating mode. When the pin is forced to 0v, the chip is powered down and when

the pin is at float (or Vcc/2) and at 5v, the mode is set to Bypass and TruBass Enabled respectively.

An additional +6dB gain is enabled by pulling the pin TBGAIN to ground.

6 Speaker Size and Filter Center Frequencies selection

The configuration of the TruBass band-pass filters depends on the speaker size for the system. There are three configurations:

small, medium and large. Each configuration uses three bandpass filters, but with different center frequencies for the filters as

follows:

Speaker Size

Filter Center Frequencies

Small

100Hz

Medium

60Hz

Large

40Hz

The low pass filter cutoff frequency and the band pass filter center frequencies can be adjusted to match the frequency response of

the speakers being used. Generally, the speaker size setting should be selected so that the lowest of the band pass center

frequencies is just above the low cutoff frequency of the speaker system.

All configurations require the 100Hz filter, so its center frequency is fixed. The center frequencies of the other two filters are

configured by the external resistors placed on pins CB2, CB2A, CB2B, CB3, CB3A, CB3B.

Revision 2.4

15 April., 2002

3