QS7785PF/CF
NIPPON PRECISION CIRCUITS--1
NIPPON PRECISION CIRCUITS INC.
3D 2/4-Channel Stereo Surround Synthesizer
OVERVIEW
The QS7785PF/CF is an audio processor IC that
generates 2, 4, 5-channel stereo surround signals
from 2-channel stereo or mono sources using QSur-
roundTM technology developed and licensed by
QSound Labs, Inc.
It can create 2-channel left and right surround effect
signal for front speakers, and a rich enhanced sur-
round signal using front speakers and surround
speakers for 4-channel output. It also features a cen-
ter signal output for clear listening of vocal and
speech signals.
FEATURES
I
Surround signal output for 2-channel front speak-
ers
I
Surround signal output for 4-channel front + sur-
round speakers
I
Center speaker output for voice signals
I
Parallel and 2 serial interfaces for mode control
supported
QS7785CF: I
2
C bus 2-wire serial interface
(Data and Clock)
QS7785PF: 3-wire serial interface (Data, Clock
and Strobe)
I
5 to 13V analog supply
I
4.5 to 5.5V digital supply
I
48-pin QFP package
APPLICATIONS
I
TV, radio and VCRs
I
Car audio
I
Multimedia products
PINOUT
(Top view)
QS7785PF
QS7785CF
ORDERING INFORMATION
I
2
C bus is a registered trademark of Philips Electronics N.V.
Dolby and the double-D symbol are registered trademarks of Dolby Laboratories Licensing Corporation.
38
39
40
41
42
43
44
45
46
47
48
1
2
3
4
5
6
7
8
9
10
11
13
14
15
16
17
18
19
20
21
22
23
26
27
28
29
30
31
32
33
34
35
36
LIN
BASC2
MSC6
MSC5
MSC4
MSC3
MSC2
MSC1
QXCC1
QXCC2
QXCC3
SLOUT
COUT
CIN
LPC
VREFIN
N.C.
VREFOUT
PSAVE
MUTE
BASS
SUR(SCL)
QXCC4
QXDC1
QXDC2
QXDC3
QXDC4
GND
VDD
P/S
SP(STRB)
MONO
AC
BASC1
QXAC1
QXAC2
QXAC3
QXAC4
VCC
QXBC1
QXBC2
QXBC3
QXBC4
FROUT
12
BYP(SDA)
24
SROUT
37
RIN
25
FLOUT
QS7785PF
38
39
40
41
42
43
44
45
46
47
48
1
2
3
4
5
6
7
8
9
10
11
13
14
15
16
17
18
19
20
21
22
23
26
27
28
29
30
31
32
33
34
35
36
LIN
BASC2
MSC6
MSC5
MSC4
MSC3
MSC2
MSC1
QXCC1
QXCC2
QXCC3
SLOUT
COUT
CIN
LPC
VREFIN
N.C.
VREFOUT
PSAVE
MUTE
BASS
SUR(SCL)
QXCC4
QXDC1
QXDC2
QXDC3
QXDC4
GND
VDD
P/S
SP
MONO
AC
BASC1
QXAC1
QXAC2
QXAC3
QXAC4
VCC
QXBC1
QXBC2
QXBC3
QXBC4
FROUT
12
BYP(SDA)
24
SROUT
37
RIN
25
FLOUT
QS7785CF
Device
Package
QS7785PF
48-pin QFP
QS7785CF
48-pin QFP
QS7785PF/CF
NIPPON PRECISION CIRCUITS--2
PACKAGE DIMENSIONS
(Unit: mm)
BLOCK DIAGRAM
0.19 0.05
0.10
0.07
0.10
0.17 0.05
0 to 10
1.50
0.10
0.20
0.08
M
0.50
0.35max
1.00typ
7.00 0.20
9.00 0.20
7.00
0.20
9.00
0.20
0.50 0.10
0.339typ
BASC1
VCC
Serial I/O
Front
QEXPANDER
QXAC2
QXAC4
QXBC2
QXBC4
QXCC1
QXCC3
QXDC1
Mono to
Stereo
Multiplex/Decode/Level Shift
CIN
VREFIN
GND
29
32
34
27
46
48
2
4
31
6
19
36
21
QXBC3
28
QXBC1
30
QXAC3
33
QXAC1
35
QXCC2
47
QXCC4
1
3
5
QXDC2
QXDC3
QXDC4
Surround
QEXPANDER
RIN
37
LIN
38
BASC2
39
MSC6
40
MSC5
41
MSC4
42
MSC3
43
MSC2
44
MSC1
45
COUT
22
LPC
20
SLOUT
23
SROUT
24
FLOUT
25
FROUT
26
To internal
VREFOUT
17
PSAVE
16
MUTE
15
BASS
14
MONO
10
AC
11
SP(STRB)
9
SUR(SCL)
13
BYP(SDA)
12
N.C.
18
VDD
7
P/S
8
To internal
QS7785PF/CF
NIPPON PRECISION CIRCUITS--3
PIN DESCRIPTION
Number
Name
I/O
Description
Parallel
Serial
1
QXCC4
O
QEXPANDER C capacitor 4
2
QXDC1
I
QEXPANDER D capacitor 1
3
QXDC2
O
QEXPANDER D capacitor 2
4
QXDC3
I
QEXPANDER D capacitor 3
5
QXDC4
O
QEXPANDER D capacitor 4
6
GND
Ground
7
VDD
4.5 to 5.5V digital supply
8
P/S
I
Input mode control (HIGH: parallel, LOW: serial)
9
SP
I
Enhancement control (HIGH: high spread, LOW: low spread)
STRB
I
Serial data strobe (not applicable to QS7785CF)
10
MONO
I
Mono-to-stereo convert select (HIGH: mono to stereo mode, LOW: normal mode)
11
AC
I
Center output control (HIGH: center on, LOW: center off)
12
BYP
I
Bypass control (HIGH: bypass, LOW: Qsurround)
SDA
I/O
Serial data input (also serves as ACK signal output for I
2
C bus)
13
SUR
I
Surround speaker control (HIGH: surround speaker on, LOW: off)
SCL
I
Serial clock signal input
14
BASS
I
Bass boost mode control (HIGH: bass boost on, LOW: bass boost off)
15
MUTE
I
Mute signal control (HIGH: mute on, LOW: mute off)
16
PSAVE
I
Power save control (HIGH: power save on, LOW: power save off)
17
VREFOUT
O
V
CC
/2 reference voltage output
18
NC
No connection
19
VREFIN
I
V
CC
/2 reference voltage output (biased internally to V
CC
/2)
20
LPC
I
Center output lowpass filter
21
CIN
I
COUT output signal feedback input for front-channel output
22
COUT
O
Center signal output
23
SLOUT
O
Surround left-channel signal output
24
SROUT
O
Surround right-channel signal output
25
FLOUT
O
Front left-channel signal output
26
FROUT
O
Front right-channel signal output
27
QXBC4
O
QEXPANDER B capacitor 4
28
QXBC3
I
QEXPANDER B capacitor 3
29
QXBC2
O
QEXPANDER B capacitor 2
30
QXBC1
I
QEXPANDER B capacitor 1
31
VCC
5 to 13V DC analog supply
32
QXAC4
O
QEXPANDER A capacitor 4
33
QXAC3
I
QEXPANDER A capacitor 3
34
QXAC2
O
QEXPANDER A capacitor 2
35
QXAC1
I
QEXPANDER A capacitor 1
36
BASC1
I
Bass boost right-channel signal input
QS7785PF/CF
NIPPON PRECISION CIRCUITS--4
SPECIFICATIONS
Absolute Maximum Ratings
GND = 0V
Recommended Operating Conditions
GND = 0V
37
RIN
I
Right-channel signal input
38
LIN
I
Left-channel signal input
39
BASC2
I
Bass boost left-channel signal input
40
MSC6
I
Mono/stereo conversion filter capacitor 6
41
MSC5
I
Mono/stereo conversion filter capacitor 5
42
MSC4
I
Mono/stereo conversion filter capacitor 4
43
MSC3
I
Mono/stereo conversion filter capacitor 3
44
MSC2
I
Mono/stereo conversion filter capacitor 2
45
MSC1
I
Mono/stereo conversion filter capacitor 1
46
QXCC1
I
QEXPANDER C capacitor 1
47
QXCC2
O
QEXPANDER C capacitor 2
48
QXCC3
I
QEXPANDER C capacitor 3
Parameter
Symbol
Rating
Unit
Supply voltage range (analog)
V
CC
-
0.3 to 15
V
Supply voltage range (digital)
V
DD
-
0.3 to 7
V
Input voltage range (analog)
V
IANA
-
0.3 to V
CC
+ 0.3
V
Input voltage range (digital)
V
IDIG
-
0.3 to V
DD
+ 0.3
V
I
2
C signal input voltage (SDA, SCL)
V
IOPEN
10
V
Power dissipation
P
D
250
mW
Storage temperature range
T
stg
-
40 to 125
C
Parameter
Symbol
Rating
Unit
Supply voltage range (analog)
V
CC
5 to 13
V
Supply voltage range (digital)
V
DD
4.5 to 5.5
V
Operating temperature range
T
opr
-
20 to 85
C
Number
Name
I/O
Description
Parallel
Serial
QS7785PF/CF
NIPPON PRECISION CIRCUITS--5
DC Characteristics
V
CC
= 9V, V
DD
= 5V, GND = 0V, Ta = 25
C
Noise and THD Characteristics
V
CC
= 9V, V
DD
= 5V, GND = 0V, Ta = 25
C
Parameter
Symbol
Condition
Rating
Unit
min
typ
max
Analog input impedance
Z
AIN1
LIN, RIN
16
20
24
k
Z
AIN2
CIN
8
10
12
Reference voltage output
V
REFOUT
V
CC
/2
V
HIGH-level input voltage
V
IH
0.7V
DD
V
LOW-level input voltage
V
IL
0.3V
DD
V
Input leakage current
I
LEAK
Digital inputs, V
DD
input voltage
-
3
3
A
I
ILOPD
SDA, SCL, 10V input voltage
-
3
3
LOW-level output voltage
V
OL
ACK signal output from SDA, 3mA sink
current
0
0.4
V
Supply voltage (analog)
V
CC
5
13
V
Supply voltage (digital)
V
DD
4.5
5.5
V
Current consumption (analog)
I
CC
6
8
mA
Current consumption (digital)
I
DD
0.3
0.5
mA
Standby current (analog)
I
CCSAVE
0.1
0.2
mA
Parameter
Symbol
Condition
Rating
Unit
min
typ
max
Bypass noise voltage
N
BYP
BYP = HIGH, SUR = MONO = SP = LOW,
"A"-wgt, FLOUT, FROUT
10
20
V
RMS
Qsurround noise voltage (front)
N
QSF
SUR = SP = HIGH, BYP = MONO = LOW,
"A"-wgt, FLOUT, FROUT
20
40
V
RMS
Qsurround noise voltage (surround)
N
QSR
SUR = SP = HIGH, BYP = MONO = LOW,
"A"-wgt, SLOUT, SROUT
15
30
V
RMS
Bypass total harmonic distortion
THD
B
BYP = SUR = HIGH, MONO = SP = LOW,
LIN = RIN = 1V
RMS
, f = 1kHz, FLOUT,
FROUT, SLOUT, SROUT
0.1
%
Qsurround mono total harmonic
distortion
THD
QM
BYP = LOW, SUR = MONO = SP = HIGH,
LIN = RIN = 1V
RMS
, f = 1kHz, FLOUT,
FROUT, SLOUT, SROUT
0.1
%
QS7785PF/CF
NIPPON PRECISION CIRCUITS--6
AC Characteristics
V
CC
= 9V, V
DD
= 5V, GND = 0V, Ta = 25
C
Parameter
Symbol
Condition
Rating
Unit
min
typ
max
Bypass-mode maximum input voltage
V
B
BYP = SUR = HIGH, MONO = SP = LOW,
LIN = RIN, f = 1kHz
1.7
2.3
V
RMS
Qsurround enhanced-mode
maximum input voltage
V
Q+
BYP = MONO = SUR = LOW, SP = HIGH,
LIN = RIN, f = 1kHz
1.8
2.4
V
RMS
Qsurround-mode maximum input
voltage (surround speakers on)
V
QS
BYP = MONO = SP = LOW, SUR = HIGH,
LIN = RIN, f = 1kHz
1.3
1.7
V
RMS
Mono/stereo conversion enhanced
mode maximum input voltage
V
M+
BYP = SUR = LOW, MONO = SP = HIGH,
LIN = RIN, f = 1kHz
0.8
1.0
V
RMS
Mono/stereo conversion mode
maximum input voltage (surround
speakers on)
V
MS
BYP = SP = LOW, MONO = SUR = HIGH,
LIN = RIN, f = 1kHz
0.8
1.0
V
RMS
Bypass gain
G
BYP1
BYP = HIGH, MONO = SUR = SP = LOW,
LIN to FLOUT, RIN to FROUT, f = 1kHz
-
2
0
2
dB
Bypass gain (surround speakers on)
G
BYP2
BYP = SUR = HIGH, MONO = SP = LOW,
LIN to SLOUT, RIN to SROUT, f = 1kHz
-
2
0
2
dB
Qsurround mode gain
G
Q
BYP = MONO = SUR = SP = LOW, LIN to
FLOUT, RIN to FROUT, f = 1kHz
3.9
5.9
7.9
dB
Qsurround mode crosstalk gain
G
QX
BYP = MONO = SUR = SP = LOW, LIN to
FROUT, RIN to FLOUT, f = 1kHz
-
1.5
0.5
2.5
dB
Qsurround mode gain (surround)
G
QS
BYP = MONO = SP = LOW, SUR = HIGH,
LIN to SLOUT, RIN to SROUT, f = 1kHz
-
2.3
-
0.3
1.7
dB
Qsurround mode crosstalk gain
(surround)
G
QXS
BYP = MONO = SP = LOW, SUR = HIGH,
LIN to SROUT, RIN to SLOUT, f = 1kHz
-
1.9
0.1
2.1
dB
Qsurround enhanced mode gain
G
Q+
BYP = MONO = SUR = LOW, SP = HIGH,
LIN to FLOUT, RIN to FROUT, f = 1kHz
4.7
6.7
8.7
dB
Qsurround enhanced mode crosstalk
gain
G
QX+
BYP = MONO = SUR = LOW, SP = HIGH,
LIN to FROUT, RIN to FLOUT, f = 1kHz
1.3
3.3
5.3
dB
Mono/stereo conversion mode left-
channel gain
G
ML
BYP = SUR = SP = LOW, MONO = HIGH,
LIN = RIN, FLOUT, f = 1kHz
2.6
4.6
6.6
dB
Mono/stereo conversion mode right-
channel gain
G
MR
BYP = SUR = SP = LOW, MONO = HIGH,
LIN = RIN, FROUT, f = 1kHz
3.6
5.6
7.6
dB
Mono/stereo conversion enhanced
mode left-channel gain
G
ML+
BYP = SUR = LOW, MONO = SP = HIGH,
LIN = RIN, FLOUT, f = 1kHz
2.4
4.4
6.4
dB
Mono/stereo conversion enhanced
mode right-channel gain
G
MR+
BYP = SUR = LOW, MONO = SP = HIGH,
LIN = RIN, FROUT, f = 1kHz
3.3
5.3
7.3
dB
Mono/stereo conversion mode
surround left-channel gain
G
MSL
BYP = SP = LOW, MONO = SUR = HIGH,
LIN = RIN, SLOUT, f = 1kHz
-
3.8
-
1.8
0.2
dB
Mono/stereo conversion mode
surround right-channel gain
G
MSR
BYP = SP = LOW, MONO = SUR = HIGH,
LIN = RIN, SROUT, f = 1kHz
-
1.6
0.4
2.4
dB
SCL clock pulse period
t
0
QS7785PF
100
ns
SCL clock HIGH-level pulsewidth
t
1
QS7785PF
40
ns
SCL clock LOW-level pulsewidth
t
2
QS7785PF
40
ns
SDA setup time
t
3
QS7785PF
15
ns
SDA hold time
t
4
QS7785PF
30
ns
STRB setup time
t
5
QS7785PF
50
ns
STRB pulsewidth
t
6
QS7785PF
100
ns
STRB hold time
t
7
QS7785PF
50
ns
QS7785PF/CF
NIPPON PRECISION CIRCUITS--7
Serial Interface Timing
3-wire (QS7785PF) timing
I
2
C 2-wire (QS7785CF) timing
SCL hold time (I
2
C)
t
HD:STA
QS7785CF
4.0
s
SCL setup time (I
2
C)
t
SU:STO
QS7785CF
4.0
s
SDA hold time (I
2
C)
t
HD:DAT
QS7785CF
5.0
s
SDA setup time (I
2
C)
t
SU:DAT
QS7785CF
250
ns
SCL clock HIGH-level pulsewidth
(I
2
C)
t
HIGH
QS7785CF
4.0
s
SCL clock LOW-level pulsewidth (I
2
C)
t
LOW
QS7785CF
4.7
s
SCL rise time (I
2
C)
t
r
QS7785CF
1000
ns
SCL fall time (I
2
C)
t
f
QS7785CF
300
ns
Pin
Description
SDA
Data signal. Sets mode settings. See "Operating Modes."
SCL
Clock signal. Data is read on the rising edge.
STRB
Strobe signal. Mode switches occur on the rising edge of this signal.
Pin
Description
SDA
Data signal. Sets slave address and mode settings. Address value, {1011011}, is shown in the figure above. See "Operating Modes."
SCL
Clock signal. Data is read on the rising edge.
Parameter
Symbol
Condition
Rating
Unit
min
typ
max
SCL
BYP
SP
MONO
AC
STRB
SDA
3
t
4
t
7
t
6
t
1
t
0
t
2
t
SUR
BASS
MUTE
PSAVE
5
t
SCL
BYP
SP
SDA
MONO
AD0
AD6
f
t
r
t
HD:STA
t
SU:STO
t
I C address is {AD6
- AD0} = {1011011}
2
SUR
HIGH
t
LOW
t
SU:DAT
t
HD:DAT
t
AC
BASS
MUTE
PSAVE
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
Output signals
1
1. (dash) = no output signal.
= indicates don't care.
1 = HIGH, 0 = LOW
BYP
MONO
SUR
SP
FROUT/FLOUT
SROUT/SLOUT
1
Stereo only
0
0
0
0
Stereo Q
2
0
0
0
1
Stereo Q+
3
0
0
1
0
Stereo Q
Stereo Q1
4
0
0
1
1
Stereo Q+
Stereo Q1
5
Mono only
0
1
0
0
Mono
Stereo Q
6
0
1
0
1
Mono
Stereo Q+
7
0
1
1
0
Mono
Stereo Q
Mono
Stereo Q1
8
0
1
1
1
Mono
Stereo Q+
Mono
Stereo Q1
9
Stereo/Mono
1
0
0
Stereo bypass
10
1
0
1
Stereo bypass
Stereo bypass
11
1
1
0
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.
QS7785PF/CF
NIPPON PRECISION CIRCUITS--9
In output modes 9 to 11, the input stereo signal is
output to the speakers without processing. The
bypass function works for both stereo and mono
input signals, and is used to listen to the original sig-
nals. In mode 9, the stereo signal is output on front
speakers only. In mode 10, the stereo signal is output
on both front and surround speakers. In mode 11, the
stereo signal is output on surround speakers only.
In output mode 12, the input stereo signal is output
on front speakers, and a surround effect enhanced
signal is output on the surround speakers.
Center signal output
The center signal is output on COUT. See "Center Control."
Bass boost mode
The bass boost function is used to enhance the bass frequency component. See "Bass Boost."
Mute and power save
When PSAVE is HIGH, the analog stages of the
device are turned OFF to save power. When MUTE
is HIGH, all outputs are muted.
Control pins/SDA signal
1
1. (dash) = no output signal.
= indicates don't care.
1 = HIGH, 0 = LOW
Output signal
BYP
MONO
SUR
SP
AC
COUT
0
1
(RIN + LIN) / 2
Control pins/SDA signal
1
1.
= indicates don't care.
1 = HIGH, 0 = LOW
Output signal
BYP
MONO
SUR
SP
AC
BASS
FROUT/FLOUT
SROUT/SLOUT
COUT
0
Bass boost OFF
Bass boost OFF
Bass boost OFF
1
Bass boost ON
Bass boost ON
Bass boost ON
Control pins/SDA signal
1
1. (dash) = no output signal.
= indicates don't care.
1 = HIGH, 0 = LOW
Output signal
BYP
MONO
SUR
SP
AC
BASS
MUTE
PSAVE
FROUT/FLOUT
SROUT/SLOUT
COUT
0
0
Available
Available
Available
1
0
1
1
QS7785PF/CF
NIPPON PRECISION CIRCUITS--10
Speaker Arrangement
The QS7785PF/CF supports the following speaker arrangements.
Type A
The front speakers are placed in front and the sur-
round speakers are placed behind the audience to
create a full rich enhanced space. Since the output
signal for each channel has undergone Qsurround
processing, the audio enhancement can be reduced to
an adequate level even for television and similar sig-
nals where the left and right channels are located
close to each other.
Type B
The front speakers and surround speakers are both
placed in front of the audience, perhaps because it is
not possible to place speakers behind the audience. If
the surround speakers are turned to face outwards, to
spread the surround signal, the surround effect can
be obtained.
Type C
A center speaker can be added in the center to repro-
duce vocal and speech signals for easy listening. The
center signal is output on COUT. The signal is com-
prised of LIN and RIN signals, producing a sound
image in the center.
Type D
If a center speaker is not available or not required,
COUT can be connected to CIN using a resistor and
the center signal is then added to the front-channel
signal. The presence of the center signal added to the
front channels reproduces the center signal sound
image with virtually the same effect as that obtained
using a center speaker. The connection using a resis-
tor can be utilized for voice and similar fixed-band
signals. See "Center Control" for a description of the
method.
Type A. Two front speakers in front and two surround
speakers in rear
Type C. Front speakers and surround speakers in
front with actual center speaker
24
26
21
22
25
23
Front
Speakers
Rear
Speakers
SROUT
FROUT
CIN
COUT
FLOUT
SLOUT
37
38
RIN
LIN
24
26
21
22
25
23
SROUT
FROUT
CIN
COUT
FLOUT
SLOUT
37
38
RIN
LIN
Type B. Front speakers and surround speakers in
front
Type D. Front speakers and surround speakers in
front with center
24
26
21
22
25
23
SROUT
FROUT
CIN
COUT
FLOUT
SLOUT
37
38
RIN
LIN
24
26
21
22
25
23
SROUT
FROUT
CIN
COUT
FLOUT
SLOUT
37
38
RIN
LIN
QS7785PF/CF
NIPPON PRECISION CIRCUITS--11
Center Control
The center signal output on COUT is enabled when
AC is HIGH.
This section describes the output function whereby
fixed frequency sound sources, such as vocal and
speech signals, can be output on the center signal. As
mentioned for "Type C" and "Type D" speaker
arrangements, the center signal can be output by
direct connection to a speaker or by adding the signal
to the front-channel output using a resistor connec-
tion between CIN and COUT.
Using a center speaker
When using a speaker, a capacitor Ca can be con-
nected between LPC and COUT, forming a lowpass
filter. The
-3dB cutoff frequency of the filter is given
by the following equation.
Frequencies higher than voice tones are cut from the
signal sent to the center speaker for clear reproduc-
tion of voice-band signals.
Adding to the front-channel output
With this connection, the bass frequency components
can be removed from a signal. Capacitors Ca and Cb
and resistor Ra can be connected between CIN and
COUT to form a highpass filter. The
-3dB cutoff fre-
quency of the filter is given by the following equa-
tion.
The input signal on CIN is added equally to both
front-channel outputs FLOUT and FROUT. Frequen-
cies lower than voice tones are cut from the signal
added to the front-channel outputs for clear repro-
duction of voice-band signals.
Note: Internal resistance value, R1 and R2, may vary 15%.
f
1
2
Ca R1
---------------------------
=
f
1
2
Cb Ra R2
+
(
)
----------------------------------------
=
Center output connection
26
21
22
25
20
FROUT
CIN
COUT
FLOUT
LPC
10k
10k
10k
10k
R3:10k
Ca
R2:10k
Ra:10k
R1:20k
Front Right
Speaker
Cnter
Speaker
Front Left
Speaker
Cb:0.082
F
Close when MUTE=H
Open when MUTE=L
Close when AC=H
Open when AC=L
V
REFOUT
Center output frequency response
-6dB
G
C
3dB
f
L
f
H
3dB
Gain
Freq.
V(COUT)/V(RIN)@V(LIN)=0
V(FROUT)
or V(FLOUT)
f
L
=
2
Cb(Ra+R2)
f
H
=
1
2
CaR1
1
G
C
=20 log
Ra+R2
R3
(
)
-6dB
QS7785PF/CF
NIPPON PRECISION CIRCUITS--12
Bass Boost
With a signal input connected to BASC1 and
BASC2, a bass boost function can be implemented.
When BASS is HIGH, resistors RA and RB and
capacitor C are connected to form a lowpass filter.
The lowpass filter signal and the original signal
(RIN, LIN) are combined to boost bass frequencies.
.
Bass boost connection (Gb = 6dB, f
C
= 300Hz)
36
37
RIN
/LIN
To Internal
RB:10k
R2:20k
R1:20k
C:0.15
F
Close when BASS=H
Open when BASS=L
V
REFOUT
BASC1
/BASC2
+
RA=10k
Bass boost frequency response
G
b
0dB
f
L
f
H
Gain
Freq.
f
C
Gb=20 log
RA+RB
R1
(
)
1+
f
C
=
1+
RA+RB
R1
2
C
RA+RB
RA RB
f
L
=f
C
10
f
H
=f
C
10
1+
RA+RB
R1
log
(
)
1+2
R1
RA+RB
2
-
1
1+
RA+RB
R1
log
(
)
1+2
R1
RA+RB
2
1
QS7785PF/CF
NIPPON PRECISION CIRCUITS--13
TYPICAL APPLICATIONS
Parallel Interface
A capacitor for decoupling should be connected between supply and ground.
BASC1
VCC
QXAC2
QXAC4
QXBC2
QXBC4
QXCC1
QXCC3
QXDC1
CIN
VREFIN
GND
QXBC3
QXBC1
QXAC3
QXAC1
36
QXCC2
QXCC4
QXDC2
QXDC3
QXDC4
RIN
LIN
BASC2
MSC6
MSC5
MSC4
MSC3
MSC2
MSC1
COUT
LPC
SROUT
FLOUT
FROUT
VREFOUT
PSAVE
MUTE
BASS
MONO
AC
SP(STRB)
SUR(SCL)
BYP(SDA)
N.C.
VDD
P/S
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
9
10
11
12
37
38
39
40
41
42
43
44
45
46
47
48
SLOUT
0.01
F 0.01F
3300pF 3300pF
5 to 13V
8200pF
1000pF
0.012
F
0.082
F
2700pF
0.022
F
0.22
F
0.15
F
10k
10k
0.15
F
10k
10k
Signal In
5V
47k
8200pF
8200pF
8200pF
10
F
10
F
Signal Out
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
QS7785PF/CF
NIPPON PRECISION CIRCUITS--14
Serial Interface
QS7785PF
QS7785PF
A capacitor for decoupling should be connected between supply and ground.
BASC1
VCC
QXAC2
QXAC4
QXBC2
QXBC4
QXCC1
QXCC3
QXDC1
CIN
VREFIN
GND
QXBC3
QXBC1
QXAC3
QXAC1
36
QXCC2
QXCC4
QXDC2
QXDC3
QXDC4
RIN
LIN
BASC2
MSC6
MSC5
MSC4
MSC3
MSC2
MSC1
COUT
LPC
SROUT
FLOUT
FROUT
VREFOUT
PSAVE
MUTE
BASS
MONO
AC
SP(STRB)
SUR(SCL)
BYP(SDA)
N.C.
VDD
P/S
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
9
10
11
12
37
38
39
40
41
42
43
44
45
46
47
48
SLOUT
0.01
F 0.01F
3300pF 3300pF
5 to 13V
8200pF
1000pF
0.012
F
0.082
F
2700pF
0.022
F
0.22
F
0.15
F
10k
10k
0.15
F
10k
10k
Signal In
5V
8200pF
8200pF
8200pF
10
F
Signal Out
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
SCL
SDA
STRB
10
F
BASC1
VCC
QXAC2
QXAC4
QXBC2
QXBC4
QXCC1
QXCC3
QXDC1
CIN
VREFIN
GND
QXBC3
QXBC1
QXAC3
QXAC1
36
QXCC2
QXCC4
QXDC2
QXDC3
QXDC4
RIN
LIN
BASC2
MSC6
MSC5
MSC4
MSC3
MSC2
MSC1
COUT
LPC
SROUT
FLOUT
FROUT
VREFOUT
PSAVE
MUTE
BASS
MONO
AC
SP
SUR(SCL)
BYP(SDA)
N.C.
VDD
P/S
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
9
10
11
12
37
38
39
40
41
42
43
44
45
46
47
48
SLOUT
0.01
F 0.01F
3300pF 3300pF
5 to 13V
8200pF
1000pF
0.012
F
0.082
F
2700pF
0.022
F
0.22
F
0.15
F
10k
10k
0.15
F
10k
10k
Signal In
5V
8200pF
8200pF
8200pF
10
F
Signal Out
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
4.7
F
SCL
SDA
10
F
QS7785PF/CF
NIPPON PRECISION CIRCUITS--15
NC9818BE
2000.11
NIPPON PRECISION CIRCUITS INC. reserves the right to make changes to the products described in this data sheet in order to
improve the design or performance and to supply the best possible products. Nippon Precision Circuits Inc. assumes no responsibility for
the use of any circuits shown in this data sheet, conveys no license under any patent or other rights, and makes no claim that the circuits
are free from patent infringement. Applications for any devices shown in this data sheet are for illustration only and Nippon Precision
Circuits Inc. makes no claim or warranty that such applications will be suitable for the use specified without further testing or modification.
The products described in this data sheet are not intended to use for the apparatus which influence human lives due to the failure or
malfunction of the products. Customers are requested to comply with applicable laws and regulations in effect now and hereinafter,
including compliance with export controls on the distribution or dissemination of the products. Customers shall not export, directly or
indirectly, any products without first obtaining required licenses and approvals from appropriate government agencies.
NIPPON PRECISION CIRCUITS INC.
4-3, Fukuzumi 2-chome
Koto-ku, Tokyo 135-8430, Japan
Telephone: +81-3-3642-6661
Facsimile: +81-3-3642-6698
http://www.npc.co.jp/
Email: sales
@
npc.co.jp
NIPPON PRECISION CIRCUITS INC.
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