SGS Thomson Microelectronics TDA7461ND Datasheet



CAR RADIO SIGNAL PROCESSOR

HIGH PERFORMANCE SIGNAL PROCES­SOR FOR CARRADIO SYSTEMS

DEVICE INCLUDES AUDIO PROCESSOR,
STEREO DECODER, NOISEBLANKER AND
MULTIPATHDETECTOR

NO EXTERNAL COMPONENTS REQUIRED
FULLY PROGRAMMABLEVIA I
LOW DISTORTION
LOW NOISE

2

C BUS

TDA7461N

SO28

DESCRIPTION

The TDA7461N is a high performance signal
processor specifically designed for car radio ap­plications.

The device includes a complete audioprocessor
and a stereo decoder with noiseblanker,
stereoblend and all signal processing functions
necessary for state-of-the-artas well as future car
radio systems.

Switched-capacitors design technique allows to
obtain all these features without external compo-

BLOCK DIAGRAM

CDL CDG CDR

765

CASS R

CASS L

PHONE

PH GND

10

AM

3
4

INPUT

MULTIPLEXER

+

9

AUTO ZERO

8

PHONE

MIXING
STAGE

BEEP

LOUDNESS

VOLUME BASSTREBLE

ORDERING NUMBER: TDA7461ND

nents or adjustments. This means that higher
quality and reliability walks alongside an overall
cost saving.

2

The CSP is fully programmable by I

C bus inter­face allowing to customize key device parameters
and especiallyfilter characteristics.

The BICMOS process combined with the opti­mized signal processing assure low noise and
low distortionperformances.

ACOUTL

ACOUTR

ACINL

SMUTE

SOFT
MUTE

DIGITAL CONTROL

ACINR

21272817

I2C BUS

OUT LR
OUT LF
OUT RR
OUT RF

23

OUT LR

25

OUT LF

22

OUT RR

24

OUT RF

18

SCL

19

SDA

16

MUX R

15

MUX L

MPX

VS

June 2000

11

80KHz

LP

21

SUPPLY

20 26 13 14 12

CREF MPIN

GND

PILOT

CANCELLATION

PLL

PIL

DET

DEMODULATOR

+ STEREO

ADJUST

+ STEREO BLEND

MULTIPATH-

DETECTOR

25KHz

LP

NOISE

BLANKER

MPOUT LEVEL

S&H

PULSE

FORMER

HIGH

CUT

CONTROL

D

A

D97AU646A

1/31

TDA7461N

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

S

amb Operating Ambient Temperature Range -40 to 85 °C

T

stg Storage Temperature Range -55 to 150 °C

T

SUPPLY

Symbol Parameter Test Condition Min. Typ. Max. Unit

S Supply Voltage 7.5 9 10 V

V

S Supply Current V

I

SVRR Ripple Rejection @ 1KHz Audioprocessor (all filters flat) 60 dB

ESD

All pins are protectedagainstESDaccording to the MIL883 standard.

PIN CONNECTION

Operating Supply Voltage 10.5 V

=9V 253035mA

S

Stereodecoder + Audioprocessor 45 dB

ACINL

ACINR

CASSR

CASSL

CDR

CDGND

CDL

PH GND

PHONE GND

AM SDA

2
3
4
5
6
7
8
9
10

MPX

LEVEL

MPIN MUXR

12
13

28
27
26
25
24
23
22
21
20
19
18
17
16

ACOUTL1
ACOUTR
CREF
OUTLF
OUTRF
OUTLR
OUTRR
VS

SCL11
SMUTE

1514MPOUT MUXL

D97AU647

THERMAL DATA

Symbol Parameter Value Unit

th-j pins Thermal Resistance Junction-pins Max 85 °C/W

R

2/31

TDA7461N

PIN DESCRIPTION

N. Name Function Type

1 ACINL Speaker Stage Input Left I
2 ACINR Speaker Stage Input Right I
3 CASSR Cassette Input Right I
4 CASSL Cassette Input Left I
5 CDR CD Right ChannelInput I
6 CDGND Ground reference CD I
7 CDL CD Left ChannelInput I
8 PHGND Phone Ground I

9 PHONE Phone Input I
10 AM AM Input I
11 MPX FMInput (MPX) I
12 LEVEL Level Input Stereodecoder I
13 MPIN Multipath Detector Input I
14 MPOUT Multipath Detector Output O
15 MUXL Multiplexer Output Left Channel (Stereodecoder Output leftselectable
16 MUXR Multiplexer Output Right Channel (StereodecoderOutput right selectable
17 SMUTE Soft Mute Drive I
18 SCL I
19 SDA I

2

C Clock Line I/O

2

C Data Line I/O
20 GND Supply Ground S
21 VS Supply Voltage S
22 OUTRR Right Rear Speaker Output O
23 OUTLR Left Rear Speaker Output O
24 OUTRF Right Front Spaeaker Output O
25 OUTLF Left Front Speaker Output O
26 CREF Reference Capacitor Pin S
27 ACOUTR Pre-speaker AC Output Right Channel O
28 ACOUTL Pre-speaker AC Output LeftChannel O

1

)O

1

)O

(1) See databyte specification - speaker attenuators
Pin type legenda:
I = Input
O = Output
I/O = Input/Output
S = Supply

3/31

TDA7461N

AUDIO PROCESSORPART

Input Multiplexer

Fully differential or quasi-differential CD and
cassettestereo input

AM mono or stereo input
Phonedifferential or single ended input

Bass Control

2nd order frequencyresponse
Center frequencyprogrammable in 4(5)steps
DC gain programmable
7 x2dB steps

Internalbeep with 2 frequencies(selectable)
Mixablephone and beep signals

Treble Control

2nd order frequencyresponse

Loudness

Secondorder frequencyresponse

Center frequencyprogrammable in 4 steps
7 x2dB steps

Program mablecenterfr equencyandqualityfactor
15 x 1dBsteps
Selectableflat-mode(constantattenuation)

Speaker Control

4 independentspeaker controls (1dB steps
controlrange 50dB)

Volume control

1dB attenuator
Max. gain 20dB
Max. attenuation79dB
Soft-stepgain control

ELECTRICALCHARACTERISTICS (V

S = 9V; Tamb =25°C; RL = 10KΩ; all gains= 0dB; f = 1KHz;

Mute Functions

Direct mute
Digitally controlled softmute with 4 program-

mabletime constants

unless otherwise specified).

Symbol Parameter Test Condition Min. Typ. Max. Unit

INPUTSELECTOR

Rin Input Resistance all inputs except Phone [phone] KΩ

Clipping Level 2.2 2.6 V
Input Separation 80 100 dB
Min. Input Gain -1 0 1 dB
Max. Input Gain 13 14 15 dB
Step Resolution 1 2 3 dB
DC Steps Adjacent Gain Step -5 0 +5 mV

to G

G

MIN

MAX

-5 1 +5 mV

G

G

G

V

CL

S

IN
IN MIN
IN MAX

STEP

V

DC

DIFFERENTIAL CD STEREO INPUT

R

in

CMRR Common ModeRejection Ratio V

N Output Noise @ Speaker

e

Input Resistance Differential 70 100 130 K

Common Mode 20 30 40 K

@ 1KHz 45 70 dB

915µV

Output

CM=1VRMS
CM =1VRMS @ 10KHz 45 60 dB

V
20Hz to 20KHz flat; allstages

0dB

DIFFERENTIAL PHONE INPUT

Rin Input Resistance Differential 10 15 20 KΩ

Common Mode 20 30 40 K

CMRR Common ModeRejection Ratio V

CM=1VRMS

V

CM=1VRMS

@ 1KHz 45 70 dB
@ 10KHz 45 60 dB

RMS

Ω
Ω

Ω

4/31

TDA7461N

ELECTRICALCHARACTERISTICS

(continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

BEEPCONTROL

VRMS Beep Level 250 350 500 mV

BMIN Lower Beep Frequency 570 600 630 Hz

f

f

BMAX

Higher Beep Frequency 1.15 1.2 1.25 KHz

MIXINGCONTROL

MLEVEL Mixing Level Source -1 0 1 dB

Source -5 -6 -7 dB
Source -10 -12 -14 dB
Beep/Phone -1 0 1 dB

VOLUMECONTROL

G

MAX

A

MAX

A

STEP

E

A

T Tracking Error 2dB

E

DC DC Steps Adjacent Attenuation Steps -3 0.1 3 mV

V

Max Gain 19 20 21 dB
Max Attenuation -83 -79 -75 dB
Step Resolution 0.5 1 1.5 dB
Attenuation Set Error G = -20 to 20dB -1.25 0 1.25 dB

G = -60 to 20dB -4 0 3 dB

From 0dB to G

MIN -7 0.5 +7 mV

LOUDNESSCONTROL

A

STEP

A

MAX

CMIN Lower Center Frequency 180 200 220 Hz

f

CMAX Higher Center Frequency 360 400 440 Hz

f

Step Resolution 0.5 1 1.5 dB
Max. Attenuation -16 -15 -14 dB

SOFTMUTE

A

MUTE

T

D

THlow Low Threshold for SM Pin

V

THhigh High Threshold for SM Pin 2.5 V

V

PU Internal Pull-up Resistor 70 100 130 KΩ

R
V

PU

Mute Attenuation 60 100 dB
Delay Time T1 0.48 1 ms

T2 0.96 2 ms
T3 20 40.4 60 ms
T4 200 324 600 ms

1

Pull-up Voltage 4.7 V

SOFTSTEP

T

SW

1) The SM pin is active low (Mute = 0)

Switch Time 5 10 15 ms

1V

5/31

TDA7461N

ELECTRICALCHARACTERISTICS

(continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

BASSCONTROL

CRANGE Control Range ±13 ±14 ±15 dB

A

STEP Step Resolution 1 2 3 dB

f

C

Q

BASS Quality Factor Q1 0.9 1 1.1

DC

GAIN

Center Frequency f

C1

f

C2

f

C3

f

C4

Q

2 1.1 1.25 1.4

Q

3

Q

4

54 60 66 Hz
63 70 77 Hz
72 80 88 Hz
90 100

(2)

110 Hz

1.3 1.5 1.7

1.8 2 2.2

Bass-Dc-Gain DC = off -1 0 +1 dB

DC = on 4 4.4 6 dB

TREBLECONTROL

C

A

RANGE

STEP

f

C

Control Range

13

±

14

±

15 dB

±

Step Resolution 1 2 3 dB
Center Frequency f

C1

f

C2 10 12.5 15 KHz

f

C3

f

C4

8 10 12 KHz

12 15 18 KHz
14 17.5 21 KHz

SPEAKERATTENUATORS

CRANGE Control Range -53 -50 -47 dB

A

A

STEP

MUTE

E

V

DC

E

Step Resolution 0.5 1 2 dB
Output Mute Attenuation 80 90 dB
Attenuation Set Error -2 2 dB
DC Steps Adjacent Attenuation Steps 0.1 5 mV

AUDIO OUTPUTS

V

CLIP

R

L

C

L Output Load Capacitance 10 nF

R

OUT Output Impedance 30 100 Ω

V

DC

Clipping Level d = 0.3% 2.2 2.6 V
Output Load Resistance 2 K

DC Voltage Level 3.6 3.8 4.0 V

GENERAL

e

NO

S/N Signal to Noise Ratio all gain = 0dB flat; V

d Distortion V

S

C Channel separation Left/Right 80 100 dB

E

T

2) See description of Audioprocessor Part - Bass & Treble filter characteristics programming

Output Noise BW = 20 Hz to 20 KHz

315µV

output muted
BW = 20 Hz to 20 KHz

6.5 15 µV

all gain = 0dB

=2V

O

RMS

bass treble at12dB; V

2.6V

RMS

=1V

IN

V

IN =1VRMS;Bass& Treble= 12dB 0.05 0.1 %

; all stages0dB 0.002 0.1 %

RMS

O =

106 dB
100 dB

Total Tracking Error AV= 0 to -20dB -1 0 1 dB

A

= -20 to -60dB -2 0 2 dB

V

RMS

Ω

6/31

TDA7461N

DESCRIPTIONOFTHE AUDIOPROCESSOR
PART

ProgrammableInput Matrix

The programmableinput matrix of the TDA7461N
offers several possibilities to adaptthe audioproc­essor to the desired application. In to the stand­ard applicationwe have:

CD quasi differential
Cassettestereo
Phonedifferential
AM mono
Stereodecoderinput.

The input matrix can be configuredby only 2 bits:

Figure 1. Input Configuration Tree

TDA7461

bits 3 and 4 of subaddress 0. Basically the bit of
subaddress 13 is fixed by the application and has
to be programmed only once at the startup of the
IC.

For many configurations the two bits are also
fixed during one application (e.g. the standardap­plication) and a change of the input source can
be done by loading the first three bits of subad­dress 0.

In other configurations for some sources a pro­gramming of bit 3 and 4 of subaddress0 is nec­essary in addition to the three source selection
bits. In every case only the subaddress 0 has to
be changed to switch from one source to another.

The followingpicture shows the input and source
programmingflow:

CD QD CD FD

APPL. 2APPL. 1 APPL. 3 APPL. 5APPL. 4 APPL. 6

CD

QD

CASSETTE

FM STD

AM

MONO

PHONE (D)

Note: in AMSTD configuration theAM mono signal is lead throughthe FM stereodecoder part touse its additionalfiltersand high-cutfunction.

CD

QD

CASSETTE

FM STD

AM

STEREO

PHONE (SE)

CD

QD

CASSETTE

FM STD

AM STD

PHONE (D)

CD FD

CASSETTE

FM STD

AM

MONO

PHONE (SE)

CD FD

CASSETTE

FM STD

AM STEREO

CD FD

CASSETTE

FM STD
AM STD

PHONE (SE)

D97AU632B

7/31

TDA7461N

PIN NUMBER

Appl. No 6 8 9 10 Programming

1CD
2CD

3CD

4 CDR
5 CDR

6 CDR

1)

Syntax 0/xxx11100 means: SUBADDRESS= 0 - DATA BYTE = xxx11100 (x - don’t care)

GND
GND

GND

GND CDLGND Phone AMMONO Startup: 0/xxxx0xxx
GND CDLGND AMRIGHT AMLEFT Startup: 0/xxxx0xxx

GND

Phone
Phone

Phone

CDL

GND

GND
GND

GND

Phone AM
AMRIGHT AM

Phone AMSTD Startup: 0/xxxx1xxx

Phone AMSTD Startup: 0/xxxx0xxx

MONO
LEFT

Startup: 0/xxx11xxx
Startup: 0/xxxx1xxx
FM

AM
Phone

FM
AM
Phone

FM
AM

FM
AM
Phone

1)

0/xxx11100
0/xxx01011
0/xxx11010

0/xxx11100
0/xxx01100
0/xxx11010

0/xxx10100
0/xxx00011

0/xxx10100
0/xxx00100
0/xxx10010

How to find the right input configuration

The best way to come to the desired configura­tion may be to go through the application tree
from the top to the bottom while making the spe­cific decisions.

This way will lead to one of the six possibleappli­cations. Then take the number of the application
and go into the pinning table. Here you will find
the special pinout as well as the special program­ming codesfor selectingsources.

For example in Appl. 6 the TDA7461N has to be
configured while startup with the databyte
0/xxxx0xxx.

To select the FM, AM or phone source the last
five significant bits of subaddress 0 have to be
changed, for any other source the last three bits
are sufficient(see data byte specification).

Input stages

Most of the input circuits are the same as in pre­ceeding ST audioprocessors with exception of
the CD inputs(see figure 2).
In the meantime there are some CD players in
the market having a significant high source im­pedance which affects strongly the common­mode rejection of the normal differential input
stage. The additional buffer of the CD input

avoids this drawback and offers the full common­moderejection even with those CD players.

The TDA7461N can be configured with an addi­tional input; if the AC coupling before the speaker
stage is not used(bit 7 in subaddress5set to ”1”)
ACINL and ACINR pins can be used as an addi­tional stereo input.

AutoZero

In order to reduce the number of pins there is no
AC coupling between the In-Gain and the follow­ing stage, so that any offset generated by or be­fore the In-Gain stage would be transferred or
even amplified to the output.

To avoid that effect a special offset cancellation
stage calledAutoZerois implemented.
To avoid audible clicks the audioprocessor is
muted before the loudness stage during this time.
In some cases, for example if the µP is executing
a refresh cycle of the I

2

C bus programming, it is
not useful to start a new AutoZeroaction because
no new source is selectedand an undesiredmute
would appear at the outputs. For such applica­tions the TDA7461N could be switched in the
”Auto Zero Remain” mode (Bit 6 of the subad­dress byte). If this bit is set to high, the DAT­ABYTE 0 could be loaded without invoking the
AutoZeroand the old adjustmentvalue remains.

8/31

Figure 2. Input stages

TDA7461N

CD

100K

CDGND

PHONE

PH_GND

CASSETTE

100K

AM

100K

MPX

100K

15K 15K

15K 15K

15K 15K

15K 15K

STEREODECODER

Mixing Stage

This stage offers the possibilityto mix the internal
beep or the phone signal to any other source.
Due to the fact that the mixing stage is also lo­cated behind the In-Gain stage fine adjustments
of the main source level can be done in this way.

-

+

-

+

IN GAIN

D97AU633A

Figure 3. Loudness Attenuation @ fc = 400Hz

(secondorder)

0.0

-5.0

Loudness

There are four parameters programmable in the
loudnessstage (see fig.3, 4,5):

- Attenuation

- Center Frequency

- LoudnessQ

- Flat Mode: in this mode the loudnessstageworks
asa 0- 15dBattenuator.

Softmute

The digitally controlled softmute stage allows
muting/demuting the signal with a I
grammable slope. The mute process can either
be activated by the softmute pin or by the I

2

C bus pro-

2

bus. The slope is realized in a special S shaped
curve to mute slow in the critical regions (see fig­ure 6).

For timing purposes the Bit 3 of the I

2

C bus out­put register is set to 1 from the start of muting un­til the end of demuting.

-10.0

-15.0

-20.0

10.0 100.0 1.0K 10.0K

Figure 4. Loudness Center frequency @ Attn.

= 15dB (second order)

0.0

-5.0

-10.0

C

-15.0

-20.0

10.0 100 .0 1.0K 10.0K

9/31

TDA7461N

Figure 5. Loudness @ Attn.= 15dB,fc = 400Hz

(dB)

-5

-10

-15

-20
10 100 1,000 Hz

D98AU844

Softstep Volume

When volume level is changed often an audible
click appears at the output. The root cause of
those clicks could be either a DC offset before
the volume stage or the sudden change of the
envelope of the audio signal. With the Softstep
feature both kinds of clickscould be reduced to a
minimum and are no more audible (see figure 7).

Bass

There are three parameters programmable in the
bass stage(see figs 8, 9, 10, 11):

Figure 6. Softmute Timing

1

EXT.

MUTE

+SIGNAL

REF

-SIGNAL

1

2

I

C

BUS

OUT

D97AU634

Note: Please notice that a startedMute action is always terminated
and could not be interruptedby a change of the mute signal.

Time

Figure 7. Soft Step Timing

VOUT

2dB

1dB

- Attenuation

- Center Frequency (60,70, 80 and 100Hz)

- Quality Factors (1, 1.25, 1.5 and 2)

DC Mode

In this mode the DC gain is increased by 4.4dB.
In addition the programmedcenter frequencyand
quality factor is decreased by 25% which can be
used to reach alternative center frequencies or
quality factors.

Treble

There are two parameters programmable in the
treblestage (see figs 12, 13):

- Attenuation

- Center Frequency (10,12.5, 15 and 17.5kHz).

Speaker Attenuator

Due to practicalaspectsthe stepsin the speaker
attenuators are not linear over the full range. At
attenuations more than 24dB the steps increase
from 1.5dB to 10dB (please see data byte specifi­cation).

10ms

-1dB

-2dB

Note: For steps more than 1dB the softstep mode should be
deactivated because it could generate a 1dB error during the
blend-time

Time

D97AU635

10/31