QS7785PF/CF
3D 2/4-Channel Stereo Surround Synthesizer
NIPPON PRECISION CIRCUITS INC.
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 QSurround™ 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 surround signal using front speakers and surround
speakers for 4-channel output. It also features a center signal output for clear listening of vocal and
speech signals.
FEATURES
■
■
■
■
Surround signal output for 2-channel front speakers
Surround signal output for 4-channel front + surround speakers
Center speaker output for voice signals
Parallel and 2 serial interfaces for mode control
supported
■
• QS7785CF: I2C bus 2-wire serial interface
(Data and Clock)
• QS7785PF: 3-wire serial interface (Data, Clock
and Strobe)
5 to 13V analog supply
4.5 to 5.5V digital supply
48-pin QFP package
■
Multimedia products
■
■
APPLICATIONS
■
■
TV, radio and VCRs
Car audio
PINOUT (Top view)
QXBC4
FROUT
FLOUT
25
CIN
LPC
MSC5
41
20
LPC
19
VREFIN
MSC4
42
19
VREFIN
18
N.C.
MSC3
43
18
N.C.
17
VREFOUT
MSC2
44
17
VREFOUT
45
16
PSAVE
MSC1
45
16
PSAVE
QXCC1
46
15
MUTE
QXCC1
46
15
MUTE
QXCC2
47
14
BASS
QXCC2
47
14
BASS
QXCC3
48
13
SUR(SCL)
QXCC3
48
13
SUR(SCL)
10
11
12
MONO
AC
BYP(SDA)
11
AC
9
10
MONO
SP
9
SP(STRB)
8
8
P/S
P/S
7
VDD
7
6
GND
VDD
5
QXDC4
6
4
QXDC3
QS7785CF
GND
3
QXDC2
12
2
BYP(SDA)
1
QXCC4
QXDC1
QS7785PF
5
MSC1
26
COUT
21
QXDC4
44
QXBC3
22
40
4
MSC2
27
39
MSC6
QXDC3
43
QXBC2
BASC2
3
MSC3
28
SLOUT
QXDC2
42
QXBC1
SROUT
23
2
MSC4
29
24
38
1
20
VCC
37
QXCC4
41
30
RIN
LIN
QXDC1
MSC5
QXAC4
FROUT
FLOUT
25
CIN
31
QXBC4
26
COUT
21
QXAC3
QXBC3
27
22
40
32
QXBC2
28
39
MSC6
QXAC2
QXBC1
29
BASC2
33
VCC
30
SLOUT
QXAC1
QXAC4
31
SROUT
23
34
QXAC3
32
24
38
BASC1
QXAC2
33
37
35
QXAC1
34
RIN
LIN
36
BASC1
35
QS7785CF
36
QS7785PF
ORDERING INFORMATION
Device
Package
QS7785PF
48-pin QFP
QS7785CF
48-pin QFP
I2C bus is a registered trademark of Philips Electronics N.V.
Dolby and the double-D symbol are registered trademarks of Dolby Laboratories Licensing Corporation.
NIPPON PRECISION CIRCUITS—1
QS7785PF/CF
PACKAGE DIMENSIONS
(Unit: mm)
0.35max
0.17 0.05
1.00typ
7.00 0.20
7.00 0.20
9.00 0.20
0.50 0.10
0.10 0.07
0.20
1.50 0.10
0 to 10
9.00 0.20
0.339typ
0.10
0.50
0.19 0.05
0.08 M
35 34 33 32 30 29 28 27
36
46 47 48
1
3
4
QXDC4
QXDC3
QXDC1
2
QXDC2
QXCC4
QXCC3
QXCC2
QXCC1
QXBC4
QXBC3
QXBC2
QXBC1
QXAC4
QXAC3
QXAC2
QXAC1
BLOCK DIAGRAM
5
BASC1
37
26
Front
QEXPANDER
38
LIN
MSC2
MSC1
VCC
GND
FLOUT
SROUT
SLOUT
43
44
21
To internal
CIN
45
22
Multiplex/Decode/Level Shift
31
20
To internal
COUT
LPC
Serial I/O
VREFIN
23
42
FROUT
19
6
17
18
16 15 14 10 11 9 13 12
7
8
P/S
MSC3
Surround
QEXPANDER
PSAVE
MUTE
BASS
MONO
AC
SP(STRB)
SUR(SCL)
BYP(SDA)
MSC4
41
N.C.
MSC5
Mono to
Stereo
MSC6
24
40
VREFOUT
BASC2
25
39
VDD
RIN
NIPPON PRECISION CIRCUITS—2
QS7785PF/CF
PIN DESCRIPTION
Name
Number
I/O
Parallel
Description
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)
SP
–
I
Enhancement control (HIGH: high spread, LOW: low spread)
–
STRB
I
Serial data strobe (not applicable to QS7785CF)
9
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)
Bypass control (HIGH: bypass, LOW: Qsurround)
BYP
–
I
–
SDA
I/O
SUR
–
I
Surround speaker control (HIGH: surround speaker on, LOW: off)
–
SCL
I
Serial clock signal input
12
Serial data input (also serves as ACK signal output for I2C bus)
13
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
VCC/2 reference voltage output
18
NC
–
No connection
19
VREFIN
I
VCC/2 reference voltage output (biased internally to VCC/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
NIPPON PRECISION CIRCUITS—3
QS7785PF/CF
Name
Number
I/O
Parallel
Description
Serial
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
SPECIFICATIONS
Absolute Maximum Ratings
GND = 0V
Parameter
Symbol
Rating
Unit
Supply voltage range (analog)
VCC
−0.3 to 15
V
Supply voltage range (digital)
VDD
−0.3 to 7
V
Input voltage range (analog)
VIANA
−0.3 to VCC + 0.3
V
Input voltage range (digital)
VIDIG
−0.3 to VDD + 0.3
V
VIOPEN
10
V
Power dissipation
PD
250
mW
Storage temperature range
Tstg
−40 to 125
°C
Symbol
Rating
Unit
Supply voltage range (analog)
VCC
5 to 13
V
Supply voltage range (digital)
VDD
4.5 to 5.5
V
Operating temperature range
Topr
−20 to 85
°C
I2C signal input voltage (SDA, SCL)
Recommended Operating Conditions
GND = 0V
Parameter
NIPPON PRECISION CIRCUITS—4
QS7785PF/CF
DC Characteristics
VCC = 9V, VDD = 5V, GND = 0V, Ta = 25°C
Rating
Parameter
Analog input impedance
Symbol
Condition
Unit
min
typ
max
ZAIN1
LIN, RIN
16
20
24
ZAIN2
CIN
8
10
12
kΩ
Reference voltage output
VREFOUT
–
VCC/2
–
V
HIGH-level input voltage
VIH
0.7VDD
–
–
V
LOW-level input voltage
VIL
–
–
0.3VDD
V
Input leakage current
ILEAK
Digital inputs, VDD input voltage
−3
–
3
IILOPD
SDA, SCL, 10V input voltage
−3
–
3
ACK signal output from SDA, 3mA sink
current
0
–
0.4
V
µA
LOW-level output voltage
VOL
Supply voltage (analog)
VCC
5
–
13
V
Supply voltage (digital)
VDD
4.5
–
5.5
V
Current consumption (analog)
ICC
–
6
8
mA
Current consumption (digital)
IDD
–
0.3
0.5
mA
ICCSAVE
–
0.1
0.2
mA
Standby current (analog)
Noise and THD Characteristics
VCC = 9V, VDD = 5V, GND = 0V, Ta = 25°C
Rating
Parameter
Symbol
Condition
Unit
min
typ
max
Bypass noise voltage
NBYP
BYP = HIGH, SUR = MONO = SP = LOW,
“A”-wgt, FLOUT, FROUT
–
10
20
µVRMS
Qsurround noise voltage (front)
NQSF
SUR = SP = HIGH, BYP = MONO = LOW,
“A”-wgt, FLOUT, FROUT
–
20
40
µVRMS
Qsurround noise voltage (surround)
NQSR
SUR = SP = HIGH, BYP = MONO = LOW,
“A”-wgt, SLOUT, SROUT
–
15
30
µVRMS
Bypass total harmonic distortion
THDB
BYP = SUR = HIGH, MONO = SP = LOW,
LIN = RIN = 1VRMS, f = 1kHz, FLOUT,
FROUT, SLOUT, SROUT
–
–
0.1
%
Qsurround mono total harmonic
distortion
THDQM
BYP = LOW, SUR = MONO = SP = HIGH,
LIN = RIN = 1VRMS, f = 1kHz, FLOUT,
FROUT, SLOUT, SROUT
–
–
0.1
%
NIPPON PRECISION CIRCUITS—5
QS7785PF/CF
AC Characteristics
VCC = 9V, VDD = 5V, GND = 0V, Ta = 25°C
Rating
Parameter
Symbol
Condition
Unit
min
typ
max
Bypass-mode maximum input voltage
VB
BYP = SUR = HIGH, MONO = SP = LOW,
LIN = RIN, f = 1kHz
1.7
2.3
–
VRMS
Qsurround enhanced-mode
maximum input voltage
VQ+
BYP = MONO = SUR = LOW, SP = HIGH,
LIN = RIN, f = 1kHz
1.8
2.4
–
VRMS
Qsurround-mode maximum input
voltage (surround speakers on)
VQS
BYP = MONO = SP = LOW, SUR = HIGH,
LIN = RIN, f = 1kHz
1.3
1.7
–
VRMS
Mono/stereo conversion enhanced
mode maximum input voltage
VM+
BYP = SUR = LOW, MONO = SP = HIGH,
LIN = RIN, f = 1kHz
0.8
1.0
–
VRMS
Mono/stereo conversion mode
maximum input voltage (surround
speakers on)
VMS
BYP = SP = LOW, MONO = SUR = HIGH,
LIN = RIN, f = 1kHz
0.8
1.0
–
VRMS
Bypass gain
GBYP1
BYP = HIGH, MONO = SUR = SP = LOW,
LIN to FLOUT, RIN to FROUT, f = 1kHz
−2
0
2
dB
Bypass gain (surround speakers on)
GBYP2
BYP = SUR = HIGH, MONO = SP = LOW,
LIN to SLOUT, RIN to SROUT, f = 1kHz
−2
0
2
dB
Qsurround mode gain
GQ
BYP = MONO = SUR = SP = LOW, LIN to
FLOUT, RIN to FROUT, f = 1kHz
3.9
5.9
7.9
dB
Qsurround mode crosstalk gain
GQX
BYP = MONO = SUR = SP = LOW, LIN to
FROUT, RIN to FLOUT, f = 1kHz
−1.5
0.5
2.5
dB
Qsurround mode gain (surround)
GQS
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)
GQXS
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
GQ+
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
GQX+
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 leftchannel gain
GML
BYP = SUR = SP = LOW, MONO = HIGH,
LIN = RIN, FLOUT, f = 1kHz
2.6
4.6
6.6
dB
Mono/stereo conversion mode rightchannel gain
GMR
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
GML+
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
GMR+
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
GMSL
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
GMSR
BYP = SP = LOW, MONO = SUR = HIGH,
LIN = RIN, SROUT, f = 1kHz
−1.6
0.4
2.4
dB
SCL clock pulse period
t0
QS7785PF
100
–
–
ns
SCL clock HIGH-level pulsewidth
t1
QS7785PF
40
–
–
ns
SCL clock LOW-level pulsewidth
t2
QS7785PF
40
–
–
ns
SDA setup time
t3
QS7785PF
15
–
–
ns
SDA hold time
t4
QS7785PF
30
–
–
ns
STRB setup time
t5
QS7785PF
50
–
–
ns
STRB pulsewidth
t6
QS7785PF
100
–
–
ns
STRB hold time
t7
QS7785PF
50
–
–
ns
NIPPON PRECISION CIRCUITS—6
QS7785PF/CF
Rating
Parameter
Symbol
Condition
Unit
min
typ
max
SCL hold time (I2C)
tHD:STA
QS7785CF
4.0
–
–
µs
SCL setup time (I2C)
tSU:STO
QS7785CF
4.0
–
–
µs
SDA hold time (I2C)
tHD:DAT
QS7785CF
5.0
–
–
µs
SDA setup time (I2C)
tSU:DAT
QS7785CF
250
–
–
ns
SCL clock HIGH-level pulsewidth
(I2C)
tHIGH
QS7785CF
4.0
–
–
µs
SCL clock LOW-level pulsewidth (I2C)
tLOW
QS7785CF
4.7
–
–
µs
SCL rise time (I2C)
tr
QS7785CF
–
–
1000
ns
SCL fall time (I2C)
tf
QS7785CF
–
–
300
ns
Serial Interface Timing
3-wire (QS7785PF) timing
SDA
BYP
SUR
SP
MONO
AC
BASS
MUTE
PSAVE
SCL
t3
t4
t1
t2
t6
t0
STRB
t7
t5
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.
I2C 2-wire (QS7785CF) timing
2
I C address is {AD6 − AD0} = {1011011}
SDA
AD6
tHD:STA
AD0
tr
BYP
tf
SUR
SP
MONO
tSU:DAT
AC
BASS
MUTE
PSAVE
tSU:STO
SCL
tHIGH
tLOW
Pin
tHD:DAT
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.
NIPPON PRECISION CIRCUITS—7
QS7785PF/CF
FUNCTIONAL DESCRIPTION
Operating Modes
The QS7785PF/CF operating mode can be controlled 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 relationship is shown in the table below. Refer to “Serial
Interface Timing” for the SDA signal format.
Output mode
Output signals1
Control pins/SDA signal
No.
Input signals
BYP
MONO
SUR
SP
FROUT/FLOUT
SROUT/SLOUT
0
0
0
0
Stereo Q
–
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
0
1
0
0
Mono → Stereo Q
–
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
1
0
0
×
Stereo bypass
–
1
0
1
×
Stereo bypass
Stereo bypass
1
1
0
×
–
Stereo bypass
1
1
1
×
Stereo bypass
Stereo Q1
1
2
Stereo only
6
Mono only
10
Stereo/Mono
11
12
Stereo only
1. – (dash) = no output signal.
× = indicates don’t care.
1 = HIGH, 0 = LOW
Output signal description
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.
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 processed 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 signal is the same as in output modes 1 and 2. The
surround-channel signal is a mixed signal comprising an enhanced surround effect Qsurround processed 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.
NIPPON PRECISION CIRCUITS—8
QS7785PF/CF
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 signals. 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
Control pins/SDA signal1
Output signal
BYP
MONO
SUR
SP
AC
COUT
×
×
×
×
0
–
×
×
×
×
1
(RIN + LIN) / 2
1. – (dash) = no output signal.
× = indicates don’t care.
1 = HIGH, 0 = LOW
The center signal is output on COUT. See “Center Control.”
Bass boost mode
Control pins/SDA signal1
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
1. × = indicates don’t care.
1 = HIGH, 0 = LOW
The bass boost function is used to enhance the bass frequency component. See “Bass Boost.”
Mute and power save
Control pins/SDA signal1
Output signal
BYP
MONO
SUR
SP
AC
BASS
MUTE
PSAVE
FROUT/FLOUT
SROUT/SLOUT
COUT
×
×
×
×
×
×
0
0
Available
Available
Available
×
×
×
×
×
×
1
0
–
–
–
×
×
×
×
×
×
1
1
–
–
–
1. – (dash) = no output signal.
× = indicates don’t care.
1 = HIGH, 0 = LOW
When PSAVE is HIGH, the analog stages of the
device are turned OFF to save power. When MUTE
is HIGH, all outputs are muted.
NIPPON PRECISION CIRCUITS—9
QS7785PF/CF
Speaker Arrangement
The QS7785PF/CF supports the following speaker arrangements.
37 RIN
SROUT 24
37 RIN
SROUT 24
38 LIN
FROUT 26
38 LIN
FROUT 26
CIN 21
COUT 22
Front
Speakers
CIN 21
Rear
Speakers
COUT 22
FLOUT 25
FLOUT 25
SLOUT 23
SLOUT 23
Type A. Two front speakers in front and two surround
speakers in rear
Type B. Front speakers and surround speakers in
front
37 RIN
SROUT 24
37 RIN
SROUT 24
38 LIN
FROUT 26
38 LIN
FROUT 26
CIN 21
CIN 21
COUT 22
COUT 22
FLOUT 25
FLOUT 25
SLOUT 23
SLOUT 23
Type C. Front speakers and surround speakers in
front with actual center speaker
Type D. Front speakers and surround speakers in
front with center
Type A
Type C
The front speakers are placed in front and the surround 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 signals where the left and right channels are located
close to each other.
A center speaker can be added in the center to reproduce vocal and speech signals for easy listening. The
center signal is output on COUT. The signal is comprised of LIN and RIN signals, producing a sound
image in the center.
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 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 resistor can be utilized for voice and similar fixed-band
signals. See “Center Control” for a description of the
method.
NIPPON PRECISION CIRCUITS—10
QS7785PF/CF
Center Control
Adding to the front-channel output
The center signal output on COUT is enabled when
AC is HIGH.
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 frequency of the filter is given by the following equation.
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 connection between CIN and COUT.
1
f = ---------------------------------------2πCb ( Ra + R2 )
Using a center speaker
The input signal on CIN is added equally to both
front-channel outputs FLOUT and FROUT. Frequencies lower than voice tones are cut from the signal
added to the front-channel outputs for clear reproduction of voice-band signals.
When using a speaker, a capacitor Ca can be connected between LPC and COUT, forming a lowpass
filter. The −3dB cutoff frequency of the filter is given
by the following equation.
1
f = --------------------------2πCa × R1
Frequencies higher than voice tones are cut from the
signal sent to the center speaker for clear reproduction of voice-band signals.
VREFOUT
Close when AC=H
Open when AC=L
Close when MUTE=H
Open when MUTE=L
LPC
R1:20k
20
FROUT
26
R3:10k
Ca
Ra:10k CIN
21
Cb:0.082µF
22
COUT
10k
10k
R2:10k
Cnter
Speaker
10k
10k
Front Right
Speaker
FLOUT
25
Front Left
Speaker
Center output connection
V(COUT)/V(RIN)@V(LIN)=0
Gain
−6dB
3dB
3dB
GC
fL=
1
1
fH=
2πCb(Ra+R2)
2πCaR1
GC=20 log
R3
( Ra+R2
)−6dB
V(FROUT)
or V(FLOUT)
fL
fH
Freq.
Center output frequency response
Note: Internal resistance value, R1 and R2, may vary ± 15%.
NIPPON PRECISION CIRCUITS—11
QS7785PF/CF
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
RIN
/LIN
+
37
RA=10k
RB:10k
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.
R1:20k
R2:20k
To Internal
36
BASC1
/BASC2
C:0.15µF
VREFOUT
Close when BASS=H
Open when BASS=L
Bass boost connection (Gb = 6dB, fC = 300Hz)
.
Gain
(
Gb=20 log 1+
Gb
R1
RA+RB
)
R1
RA+RB
RA RB
2πC
RA+RB
1+
fC=
fL=fC 10
0dB
fL
fC
fH
Freq.
−
fH=fC 10
1
2
1
2
log 1+
(
)
(
)
R1
RA+RB
1+2 RA+RB
R1
R1
RA+RB
1+2 RA+RB
R1
log 1+
Bass boost frequency response
NIPPON PRECISION CIRCUITS—12
QS7785PF/CF
TYPICAL APPLICATIONS
Parallel Interface
5 to 13V
0.01µF 0.01µF
10k
39 BASC2
1000pF
FLOUT 25
LPC 20
42 MSC4
VREFIN 19
43 MSC3
N.C. 18
44 MSC2
VREFOUT 17
45 MSC1
PSAVE 16
8 P/S
7 VDD
6 GND
5 QXDC4
4 QXDC3
3 QXDC2
2 QXDC1
1 QXCC4
46 QXCC1
8200pF
QXCC2 47
QXCC3 48
SLOUT
4.7µF
4.7µF
4.7µF
8200pF
15
14
10µF
10µF
MUTE
BASS
13
SUR(SCL)
0.012µF
41 MSC5
12 BYP(SDA)
0.082µF
23
SROUT
CIN 21
11 AC
2700pF
40 MSC6
10 MONO
0.022µF
24
COUT 22
9 SP(STRB)
0.15µF
0.22µF
FROUT 26
QXBC3 28
QXBC4 27
QXBC2 29
VCC 31
QXBC1 30
QXAC3 33
QXAC4 32
QXAC2 34
10k
37
LIN
38
10k
4.7µF
Signal Out
Signal In
4.7µF
RIN
3300pF 3300pF
4.7µF
BASC1 36
0.15µF
4.7µF
QXAC1 35
10k
8200pF 8200pF
47k
5V
A capacitor for decoupling should be connected between supply and ground.
NIPPON PRECISION CIRCUITS—13
QS7785PF/CF
Serial Interface
QS7785PF
5 to 13V
0.01µF 0.01µF
10k
39 BASC2
40 MSC6
1000pF
FLOUT 25
LPC 20
42 MSC4
VREFIN 19
43 MSC3
N.C. 18
44 MSC2
VREFOUT 17
45 MSC1
PSAVE 16
8 P/S
7 VDD
6 GND
5 QXDC4
4 QXDC3
3 QXDC2
2 QXDC1
8200pF
QXCC2 47
QXCC3 48
1 QXCC4
46 QXCC1
11 AC
0.012µF
41 MSC5
10 MONO
2700pF
0.082µF
23
SROUT
SLOUT
4.7µF
4.7µF
4.7µF
CIN 21
9 SP(STRB)
0.022µF
24
COUT 22
12 BYP(SDA)
0.15µF
0.22µF
FROUT 26
QXBC3 28
QXBC4 27
QXBC2 29
VCC 31
QXBC1 30
QXAC3 33
QXAC4 32
QXAC2 34
37
LIN
38
10k
10k
4.7µF
Signal Out
Signal In
4.7µF
RIN
BASC1 36
4.7µF
3300pF 3300pF
4.7µF
0.15µF
QXAC1 35
10k
15
14
13
10µF
10µF
MUTE
BASS
SUR(SCL)
SCL
8200pF
SDA
STRB
8200pF 8200pF
5V
QS7785PF
5 to 13V
0.01µF 0.01µF
10k
39 BASC2
0.022µF
2700pF
0.082µF
0.012µF
1000pF
FLOUT 25
24
23
40 MSC6
LPC 20
42 MSC4
VREFIN 19
43 MSC3
N.C. 18
44 MSC2
VREFOUT 17
45 MSC1
PSAVE 16
11 AC
10 MONO
9 SP
8 P/S
7 VDD
6 GND
5 QXDC4
4 QXDC3
3 QXDC2
2 QXDC1
46 QXCC1
1 QXCC4
SLOUT
4.7µF
4.7µF
4.7µF
CIN 21
41 MSC5
8200pF
QXCC2 47
QXCC3 48
SROUT
COUT 22
12 BYP(SDA)
0.15µF
0.22µF
FROUT 26
QXBC4 27
QXBC3 28
QXBC2 29
VCC 31
QXBC1 30
QXAC4 32
QXAC3 33
10k
37
LIN
38
10k
4.7µF
Signal Out
Signal In
4.7µF
RIN
QXAC2 34
4.7µF
3300pF 3300pF
4.7µF
BASC1 36
0.15µF
QXAC1 35
10k
15
14
13
10µF
10µF
MUTE
BASS
SUR(SCL)
8200pF
SCL
SDA
8200pF 8200pF
5V
A capacitor for decoupling should be connected between supply and ground.
NIPPON PRECISION CIRCUITS—14
QS7785PF/CF
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.
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: [email protected]
NC9818BE
2000.11
NIPPON PRECISION CIRCUITS—15