QS7785PF/CF

NIPPON PRECISION CIRCUITS—8

FUNCTIONAL DESCRIPTION

Operating Modes

The QS7785PF/CF operating mode can be con-

trolled over either a parallel interface (P/S = HIGH)

or one of two serial interfaces (P/S = LOW). The

operating mode, control pins and SDA signal rela-

tionship is shown in the table below. Refer to “Serial

Interface Timing” for the SDA signal format.

Output mode

Output signal description

Mono signals should be input on both LIN and RIN.

In output mode 1, the output signal is a mixed signal

comprising the front-channel Qsurround processed

signal and the input stereo signal, that is output on

the 2-channel front speakers only.

In output mode 2, the signal path is the same as in

output mode 1, but the surround effect is enhanced

by increasing the component of the Qsurround pro-

cessed signal and reducing the component of the

input stereo signal.

In output modes 3 and 4, both the front speakers and

surround speakers are used to form a 4-channel sys-

tem for a rich surround space. The front-channel sig-

nal is the same as in output modes 1 and 2. The

surround-channel signal is a mixed signal compris-

ing an enhanced surround effect Qsurround pro-

cessed signal and the input stereo signal.

In output modes 5 to 8, the input signal is a mono

signal. The mono signal is first converted to a virtual

stereo signal and then processed in the same way as

in output modes 1 to 4, respectively. In modes 5 and

6, the surround signal is output on 2-channel front

speakers only. In modes 7 and 8, the surround signals

are output on 4-channel front and surround speakers.

No.

Input signals

Control pins/SDA signal

1. – (dash) = no output signal.

× = indicates don’t care.

1 = HIGH, 0 = LOW

BYP

MONO

SUR

SP

FROUT/FLOUT

SROUT/SLOUT

1

Stereo only

0000

Stereo Q

–

2

0001

Stereo Q+

–

3

0010

Stereo Q

Stereo Q1

4

0011

Stereo Q+

Stereo Q1

5

Mono only

0100

Mono

→ Stereo Q

–

6

0101

Mono

→ Stereo Q+

–

7

0110

Mono

→ Stereo Q

Mono

→ Stereo Q1

8

0111

Mono

→ Stereo Q+

Mono

→ Stereo Q1

9

Stereo/Mono

100

×

Stereo bypass

–

10

101

×

Stereo bypass

Stereo bypass

11

110

×

–

Stereo bypass

12

Stereo only

1

1

1

×

Stereo bypass

Stereo Q1

Output signal

Description

Stereo Q

Mixed front-channel Qsurround processed signal and input stereo signal output

Stereo Q+

Same as Stereo Q with increased Qsurround signal component and reduced input stereo signal component.

Stereo Q1

Mixed surround-channel Qsurround processed signal and input stereo signal output.

Mono

→ Stereo Q

Mono signal converted to virtual stereo signal, and then processed in the same way as Stereo Q signals.

Mono

→ Stereo Q+

Mono signal converted to virtual stereo signal, and then processed in the same way as Stereo Q+ signals.

Stereo bypass

Input stereo signal is output as-is without processing.