Datasheet TDA7461ND Datasheet (SGS Thomson Microelectronics)



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

TDA7461N

Figure 8. Bass Control @ fc = 80Hz, Q = 1

15.0

10.0

5.0

0.0

-5.0

-10.0

-15.0

10.0 100.0 1.0K 10.0K

Figure 10. Bass Quality factors @ Gain =

14dB, fc = 80Hz

15.0

12.5

10.0

7.5

5.0

Figure 9. Bass Center@ Gain= 14dB, Q = 1

15.0

12.5

10.0

7.5

5.0

2.5

0.0

10.0 10 0.0 1.0K 10.0K

Figure 11. Bass normal and DC Mode @ Gain

= 14dB, fc = 80Hz

15.0

12.5

10.0

7.5

5.0

2.5

2.5

0.0

10.0 100.0 1.0K 10.0K

Figure 12. Treble Control @ fc = 17.5KHz

15.0

10.0

5.0

0.0

-5. 0

-10.0

-15.0

10.0 100.0 1.0K 10.0K

0.0

10.0 100.0 1.0K 10.0K

Note: In general the center frequency, Q and DC-mode can be set
independently. The exceptionfromthis ruleisthemode(5/xx1111xx)
where the center frequency is setto 150Hz instead of 100Hz.

Figure 13. Treble Center Frequencies

@ Gain = 14dB

15.0

12.5

10.0

7.5

5.0

2.5

0.0

10.0 100.0 1.0K 10.0K

11/31

TDA7461N

STEREODECODERPART

No external componentsnecessary
PLL with adjustmentfree fully integratedVCO
Automatic pilot dependent MONO/STEREO

switching
Very high suppression of intermodulation and

interference
ProgrammableRoll-Off compensation

ELECTRICAL CHARACTERISTICS

75KHz deviation, f = 1KHz. G

I = 6dB, Tamb =25°C; unless otherwise specified).

(V

S

= 9V; deemphasis time constant = 50µs, V

Dedicated RDS Softmute
Highcut and Stereoblend characterisctics pro-

grammablein a wide range
Internal Noiseblankerwith thresholdcontrols
Multipath detector with programmable inter-

nal/external influence

2

C bus controlof all necessary functions

I

MPX

= 500mV,

Symbol Parameter Test Condition Min. Typ. Max. Unit

IN MPX Input Level InputGain = 3.5dB 0.5 1.25 VRMS

V
R

in

min Minimum Input Gain 1.5 3.5 4.5 dB

G

G

max

G

STEP

SVRR Supply Voltage Ripple Rejection V

α

Input Resistance 70 100 130 K

Max Input Gain 8.5 11 12.5 dB
Step Resolution 1.75 2.5 3.25 dB

= 100mv, f = 1khz 55 dB

ripple

Max Channel Separation 30 50 dB

THD Total Harmonic Distortion 0.02 0.3 %

S+N

Signal plus Noise to Noise Ratio S = 2V

rms

80 91 dB

N

MONO/STEREOSWITCH

V

PTHST1

V

PTHST0

V

PTHMO1

V

PTHMO0

Pilot Threshold Voltage forStereo, PTH = 1 10 15 25 mV
Pilot Threshold Voltage forStereo, PTH = 0 15 25 35 mV
Pilot Threshold Voltage forMono, PTH = 1 7 12 17 mV
Pilot Threshold Voltage forStereo, PTH = 0 10 19 25 mV

Ω

PLL

∆f/f Capture Range 0.5 %

DEEMPHASISand HIGHCUT (5)

τHC50

τ

HC75

τ

HC50

τ

HC75

Deemphasis Time Constant Bit = 7, Subadr. 10 = 0

V

LEVEL >> VHCH

Deemphasis Time Constant Bit = 7, Subadr. 10 = 1

VLEVEL >> V

HCH

Highcut Time Constant Bit= 7, Subadr. 10 = 0

VLEVEL >> V

HCL

Highcut Time Constant Bit= 7, Subadr. 10 = 1

VLEVEL >> V

HCL

25 50 75

50 75 100

100 150 200

150 225 300

STEREOBLENDand HIGHCUT-CONTROL

REF5V Internal Reference Voltage 4.7 5 5.3 V

TC

REF5V

L

Gmin

Gmax Max. LEVEL Gain 8 10 12 dB

L
L

Gstep

VSBL
VSBL
VSBL

12/31

Temperature Coefficient 3300 ppm
Min. LEVEL Gain -1 0 +1 dB

LEVEL Gain Step Resolution 0.3 0.67 1.0 dB

min Min.Voltage for Mono 29 33 37 %REF5V

Max. Voltage for Mono 54 58 62 %REF5V

max

Step Resolution 5.0 8.4 12 %REF5V

step

s

µ

s

µ

s

µ

s

µ

TDA7461N

ELECTRICALCHARACTERISTICS

(continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

STEREOBLENDand HIGHCUT CONTROL

VHCH
VHCH
VHCH

VHCL

VHCL

Min.Voltage for NO Highcut 36 42 46 %REF5V

min

Max. Voltage for NO Highcut 62 66 70 %REF5V

max
step Step Resolution 5 8.4 12 %REF5V

Min. Voltage for FULL High cut 13 17 21 %VHCH

min

max Max.Voltagefor FULLHigh cut 29 33 37 %VHCH

Carrierand harmonicsuppressionat the output

19 Pilot Signal f = 19KHz 40 50 dB

α

38 Subcarrier f = 38KHz 75 dB

α

57 Subcarrier f = 57KHz 62 dB

α

76 Subcarrier f = 76KHz 90 dB

α

Intermodulation(Note1)

α2 Pilot Signal f

3f

α

= 10KHz; f

mod

= 13KHz; f

mod

= 1KHz; 65 dB

spur

= 1KHz; 75 dB

spur

Traffic Radio (Note 2)

57 Signal f = 57KHz 70 dB

α

SCA - SubsidiaryCommunicationsAuthorization(Note 3)

α67 Signal f = 67KHz 75 dB

ACI - AdjacentChannelInterference(Note 4)

114 Signal f = 114KHz 95 dB

α

190 Signal f = 190KHz 84 dB

α

Notes to the characteristics:

1. Intermodulation Suppression: measured with:91% pilot signal; fm = 10kHz or 13kHz.

2. TrafficRadio (V.F.) Suppression: measured with: 91% stereo signal; 9% pilot signal; fm=1kHz; 5% subcarrier (f = 57kHz,
fm = 23Hz AM, m = 60%)

3. SCA (Subsidiary Communications Authorization ) measured with: 81% mono signal; 9% pilot signal; fm = 1kHz; 10%SCA - subcarrier
( fs = 67kHz, unmodulated ).

4. ACI (Adjacent Channel Interference ) measured with: 90% mono signal; 9% pilot signal; fm =1kHz; 1% spurious signal

( fs = 110kHz or 186kHz, unmodulated).

5. By Design/Characterization but functionally guaranteed through dedicated test mode structure

13/31

TDA7461N

NOISE BLANKER PART

tion, field-strenght)

internal 2nd order 140kHz high pass filter
programmabletrigger threshold

very low offset current during hold time
four selectable pulse suppressiontimes

additionalcircuits for trigger adjustment (devia-

ELECTRICALCHARACTERISTICS (continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

TR TriggerThreshold

V

TRNOISE

Noise Controlled Trigger
Threshold

2)

VRECT Rectifier Voltage VMPX = 0mV 0.5 0.9 1.3 V

V

RECT DEV

deviation dependent
rectifier Voltage

VRECT FS Fieldstrength Controlled

Rectifier Voltage

0) All thresholds are measured using a pulse with TR=2µs, T

1) NBT representsthe Noiseblanker-Byte bits D2; D0 for the noise blanker trigger threshold

2) NAT representsthe Noiseblanker-Byte bit pair D4,D3 for the noise controlled trigger adjustment

3) OVD represents the Noiseblanker-Byte bit pair D7,D6 for the over deviation detector

4) FSC representsthe Fieldstrength-Byte bitpair D1,D0 for the fieldstrength control

0) 1)

meas. with VPEAK = 0.9V NBT = 111 30 mVOP

NBT = 110 35 mVOP
NBT = 101 40 mV
NBT = 100 45 mV
NBT = 011 50 mV
NBT = 010 55 mV
NBT = 001 60 mVOP
NBT = 000 65 mVOP

meas. with V

= 1.5V NCT = 00 260 mV

PEAK

NCT = 01 220 mV
NCT = 10 180 mV
NCT = 11 140 mV

V

MPX = 50mV; f= 150KHz 1.5 1.7 2.1 V

V

MPX = 100mV; f = 150KHz 2.2 2.5 2.9 V

3)

means. with
V

MPX = 800mV

(75KHz dev.)

OVD = 11 0.5 0.9(off) 1.3 V
OVD = 10 0.9 1.2 1.5 V
OVD = 01 1.7 2.0 2.3 V
OVD = 00 2.5 2.8 3.1 V

4)

means. with
V

= 0mV

MPX

V

<< V

LEVEL

SBL

(fully mono)

=2µs and TF=10µs.

HIGH

FSC = 11 0.5 0.9(off) 1.3 V
FSC = 10 1.0 1.3 1.6 V
FSC = 01 1.5 1.8 2.1 V
FSC = 00 2.0 2.3 2.6 V

OP
OP
OP
OP

OP
OP
OP
OP

OP
OP
OP
OP

14/31

V

IN

DC

D97AU636

V

OP

TRT

HIGH

T

F

Time

Figure 14. Trigger Threshold vs. VPEAK

VTH

TDA7461N

260mV(00)
220mV(01)
180mV(10)
140mV(11)

MIN. TRIG. THRESHOLD

8 STEPS

65mV

30mV

0.9V

D97AU648

Figure 15. Deviation Controlled Trigger Adjustment

V

PEAK

(VOP)

2.8

2.0

1.2

0.9

D97AU649

20

32.5 45 75

NOISE

CONTROLLED

TRIG. THRESHOLD

V

1.5V

PEAK(V)

00

01

10

DETECTOR OFF (11)

DEVIATION(KHz)

Figure 16. FieldstrengthControlled Trigger Adjustment

V

PEAK

MONO STEREO

»3V

NOISE

noisy signal good signal

D98AU863

ATC_SB OFF (11)

2.3V(00)

1.8V(01)

1.3V(10)

0.9V

E’

15/31

TDA7461N

MULTIPATH DETECTOR

Internal19kHz bandpassfilter
Programmablebandpass and rectifier gain

ELECTRICALCHARACTERISTICS (continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

CMP Center frequency of Multipath-

f

Bandpass

G

BPMP

G

RECTMP

CHMP Rectifier Charge Current 1 µA

I

DISMP Rectifier Discharge Current 1.5 mA

I

Bandpass Gain bitsD2,D1configuration byte= 00 6 dB

Rectifier Gain bitsD7,D6configuration byte= 00 7.6 dB

stereodecoder locked on pilot
tone

bitsD

2,D1

bitsD

2,D1

bitsD

2,D1

bitsD

7,D6

bitsD

7,D6

Two pin solution fully independent usable for
externalprogramming

Selectable internalinfluence on Stereoblend

19 KHz

configuration byte= 01 16 dB
configuration byte= 10 12 dB
configuration byte= 11 18 dB

configuration byte= 01 4.6 dB
configuration byte= 10 0 dB

Figure 17. Block diagram of the stereodecoder

MPX

100K

INGAIN

3.5 ... 11dB
STEP 2.5dB

INFILTER

LP

80KHz

4.th ORDER

PLL

+

PILOT-DET.

F19
F38

STEREO

NOISE BLANKER

HOLDN

D97AU762

DEMODULATOR

- PLOT

CANC

- ROLL-OFF

- LP 25KHz

COMP.

SB CONTROL

DEEMPHASIS

+ HIGHCUT

t=50 or 75µs

HC

CONTROL

REF 5V
VSBL

MPINFL

-

LEVEL INTERN

MULTIPATH
DETECTOR

D

A

LEVEL INPUT

LP 2.2KHZ

1.th ORDER
GAIN 0..10dB

FM_L

FM_R

VHCCH
VHCCL

LEVEL

MPIN

MPOUT

16/31

TDA7461N

DESCRIPTIONOFSTEREODECODER

The stereodecoder part of the TDA7461N (see
Fig. 17) contains all functions necessary to de­modulate the MPX signal like pilot tone depend­ent MONO/STEREO switching as well as
”stereoblend”and ”highcut”functions.

Adaptations like programmable input gain, roll-off
compensation, selectable deemphasis time con­stant and a programmable fieldstrength input al­low to use different IF devices.

StereodecoderMute

The TDA7461N has a fast and easy to control
RDS mute function which is a combinationof the
audioprocessor softmute and the high-ohmic
mute of the stereodecoder. If the stereodecoder
is selected and a softmute command is sent (or
activated through the SM pin) the stereodecoder
will be set automatically to the high-ohmic mute
condition after the audio signal has been soft­muted.

Hence a checking of alternate frequencies could
be performed. To release the system from the
mute condition simply the unmute command must
be sent: the stereodecoder is unmuted immedi­ately and the audioprocessor is softly unmuted.
Fig. 18 shows the output signal V

as well as the

O

internal stereodecoder mute signal. This influ­ence of Softmute on the stereodecodermute can
be switched off by setting bit 3 of the Softmute
byte to ”0”. A stereodecodermute command (bit
0, stereodecoder byte set to ”1”) will set the
stereodecoder in any case independently to the
high-ohmicmute state.

If any other source than the stereodecoderis se­lected the decoder remains muted and the MPX
pin is connectedto Vref to avoidany discharge of
the coupling capacitor throughleakage currents.

Input Stages

The Ingain stage allows to adjust the MPX signal
to a magnitude of about 1Vrms internally which is
the recommended value. The 4.th order input fil­ter has a corner frequency of 80kHz and is used
to attenuatespikes and noise and acts as an anti­aliasing filter for the following switch capacitor fil­ters.

Figure 18. Signals during stereodecoder’s

softmute

SOFTMUTE

COMMAND

t

STD MUTE

t

V

O

D97AU638

t

lowpass behaviour of the tuner section. If the
tuner attenuation at 38kHz is in a range from

20.2% to 31% the TDA7461N needs no external
network before the MPX pin. Within this range an
adjustment to obtain at least 40dB channel sepa­ration is possible.

The bits for this adjustment are located together
with the fieldstrengthadjustment in one byte. This
gives the possibility to perform an optimization
step during the production of the carradio where
the channel separation and the fieldstrengthcon­trol are trimmed.

Deemphasisand Highcut.

The lowpass filter for the deemphasis allows to
choose between a time constant of 50µs and
75µs (bit D7, Stereodecoderbyte).

The highcut control range will be in both cases
t

HC

=2⋅t

. Inside the highcut control range

Deemp

(between VHCH and VHCL) the LEVEL signal
is converted into a 5 bit word which controls the
lowpasstime constant betweent

Deemp

...3 ⋅ t

Deemp

There by the resolution will remain always 5 bits
independentlyof the absolute voltage range be­tween the VHCH and VHCL values.

The highcut function can be switched off by I2C
bus (bit D7, Fieldstrengthbyte set to ”0”).

.

Demodulator

In the demodulator block the left and the right
channel are separated from the MPX signal. In
this stage also the 19 kHz pilot tone is cancelled.
For reaching a high channel separation the
TDA7461N offers an I2C bus programmable roll­off adjustment which is able to compensate the

PLL and Pilot ToneDetector

The PLL has the task to lock on the 19kHz pilo­tone during a stereo transmission to allow a cor­rect demodulation.The included detector enables
the demodulation if the pilot tone reaches the se­lected pilottone threshold VPTHST. Two different
thresholdsare available. The detector output (sig­nal STEREO, see block diagram) can be checked

17/31

TDA7461N

by reading the status byte of the TDA7461N via
I2C bus.

FieldstrengthControl

The fieldstrength input is used to control the high
cut and the stereoblend function. In addition the
signal can be also used to control the noise­blanker thresholds.

LEVEL Input and Gain

To suppress undesired high frequency modula­tion on the highcut and stereoblend function the
LEVEL signal is lowpass filtered firstly. The filter
is a combination of a 1st order RC lowpass at
53kHz (working as anti-aliasing filter) and a 1st­order switched capacitor lowpass at 2.2kHz. The
second stage is a programmable gain stage to
adapt the LEVEL signal internally to different IF.

The gain is widely programmable in 16 steps
from 0dB to 10dB (step = 0.67dB). These 4 bits
are located together with the Roll-Off bits in the
”Stereodecoder Adjustment” byte to simplify a
possible adaptation during the production of the
carradio.

StereoblendControl

The stereoblend control block converts the inter­nal LEVEL voltage (LEVEL INTERN) into an de­modulatorcompatible analog signal whichis used
to control the channel separation between 0dB
and the maximum separation. Internally this con­trol range has a fixed upper limit which is the in­ternal reference voltage REF5V. The lower limit
can be programmed to be 33%, 42%, 50% or
58% of REF5V(see fig. 20).

To adjust the external LEVEL voltage to the inter­nal range two values must be defined: the LEVEL

Figure 19. Internal stereoblend characteristics

gain L

and VSBL. To adjust the voltage where

G

the full channel separation is reached (VST) the
LEVEL gain L

has to be defined. The following

G

equation can be usedto estimatethe gain:

=

L

G

Field strength voltage [STEREO]

REF5V

The gain can be programmed through 4 bits in
the ”Stereodecoder-Adjustment”byte.

The MONO voltage VMO (0dB channel separa­tion) can be choosen selecting 33, 42, 50 or 58%
of REF5V.
All necessary internal reference voltages like
REF5V are derived from a bandgap circuit.
Therefore they have a temperature coefficient
near zero. This is useful if the fieldstrength signal
is also temperaturecompensated.

But mostIF devices apply a LEVEL voltage with a
TC of 3300ppm. The TDA7461N offers this TC
for the reference voltages, too. The TC is select­able with bit D7 of the ”stereodecoder adjust­ment” byte.

Figure 20. Relation between internal and external LEVEL voltage and setup of Stereoblend

INTERNAL

VOLTAGES

REF 5V

18/31

VSBL

SETUP OF VST

LEVEL INTERN

LEVEL

VSTVMO

t

FIELDSTRENGHT VOLTAGE

INTERNAL

VOLTAGES

REF 5V

VSBL

58%
50%
42%
33%

D97AU639

SETUP OF VMO

VMO FIELDSTRENGHT VOLTAGE

LEVEL INTERN

VST

t

TDA7461N

Highcut Control

The highcut control setup is similar to the
stereoblend control setup : the starting point
VHCH can be set with 2 bits to be 42, 50, 58 or
66% of REF5V whereas the range can be set to
be 17 or 33% of VHCH(see fig. 21).

Figure 21. Highcut characteristics

LOWPASS

TIME CONSTANT

3•τ

Deemp

τ

Deemp

D97AU640

FIELDSTRENGHTVHCHVHCL

FUNCTIONAL DESCRIPTION OF THE NOISE­BLANKER

In the automotive environment the MPX signal is
disturbed by spikes produced by the ignition and
for example the wiper motor. The aim of the
noiseblanker part is to cancel the audible influ­ence of the spikes. Therefore the output of the
stereodecoder is held at the actual voltage for
40µs.

In a first stage the spikes must be detected but to
avoid a wrong triggering on high frequency
(white) noise a complex trigger control is imple­mented. Behind the triggerstage a pulse former
generates the ”blanking” pulse. To avoid any
crosstalk to the signalpath the noiseblanker is

suppliedby his own biasing circuit.

TriggerPath

The incoming MPX signal is highpass filtered,
amplified and rectified. This second order high­pass-filter has a corner frequency of 140kHz. The
rectified signal, RECT, is lowpass filtered to gen­erate a signal called PEAK. Also noise with a fre­quency 140kHz increases the PEAK voltage. The
PEAK voltage is fed to a threshold generator,
which adds to the PEAK voltage a DC depend­ent threshold VTH. Both signals, RECT and
PEAK+VTH are fed to a comparator which trig­gers a re-triggerable monoflop. The monoflop’s
output activates the sample-and-hold circuits in
the signalpathfor 40µs.

The block diagram of the noiseblankeris given in
fig.22.

Automatic Noise Controlled Threshold Adjust­ment (ATC)

There are mainly two independentpossibilities for
programmingthe trigger threshold:

a the low threshold in 8 steps(bitsD0 to D2 of

the noiseblankerbyte)

b the noise adjusted thresholdin 4 steps

(bits D3 and D4 of the noiseblankerbyte,
see fig. 14).

The low threshold is active in combination with a
good MPX signal without any noise; the PEAK
voltage is less than 1V. The sensitivity in this op­eration is high.

If the MPX signal is noisy the PEAK voltage in­creases due to the higher noise, which is also
rectified. With increasing of the PEAK voltage the
trigger threshold increases, too. This particular
gain is programmable in 4 steps(seefig. 14).

Figure 22. Block diagram of the noiseblanker

MPX

HIGH PASS

RECTIFIER

LOWPASS

D98AU861

RECT

+

-

VTH

+

PEAK

+

MONOFLOP HOLDN

THRESHOLD

GENERATOR

ADDITIONAL
THRESHOLD

CONTROL

19/31

TDA7461N

Automatic Threshold Control

Besides the noise controlled threshold adjust­ment there is an additionalpossibility for influenc­ing the trigger threshold. It is depending on the
stereoblendcontrol.

The point where the MPX signal starts to become
noisy is fixed by the RF part. Therefore also the
starting point of the normal noise-controlled trig­ger adjustment is fixed (fig. 16). In some cases
the behaviour of the noiseblanker can be im­proved by increasing the threshold even in a re­gion of higher fieldstrength. Sometimes a wrong
triggering occures for the MPXsignal often shows
distortion in this range which can be avoided
even if using a low threshold.

Because of the overlap of this range and the
range of the stereo/monotransitionit can be con­trolled by stereoblend. This threshold increase is
programmable in 3 steps or switched off with bits
D0 and D1 of the fieldstrengthcontrol byte.

Over Deviation Detector

If the system is tuned to stations with a high de­viation the noiseblanker can trigger on the higher
frequencies of the modulation. To avoid this
wrong behaviour, which causes noise in the out­put signal, the noiseblankeroffers a deviation de­pendent threshold adjustment.

By rectifying the MPX signal a further signal rep­resenting the actual deviation is obtained. It is

used to increase the PEAK voltage. Offset and
gain of this circuit are programmable in 3 steps
with the bits D6 and D7 of the stereodecoderbyte
(the first step turns off the detector,see fig. 15).

FUNCTIONAL DESCRIPTION OF THE MULTI­PATH DETECTOR

Using the internal detector the audible effects of a
multipath condition can be minimized.A multipath
condition is detected by rectifying the 19kHz
spectrumin thefieldstrengthsignal.

Selecting the ”internal influence” in the configura­tion byte, the channel separation is automatically
reduced during a multipath condition according to
the voltage appearing at theMPOUTpin.

To obtain a optimal performance an adaptationis
necessary.Thereforethe gain of the 19kHz band­pass is programmablein four steps as well as the
rectifier gain. The attack and decay times can be
set by the external capacitorvalue.

TEST MODE

During the test mode which can be activated by
setting bit D0 of the testing byte and bit D5 of the
subaddress byte to ”1” several internal signals
are available at the CASSR pin. During this
mode the input resistance of 100kOhmis discon­nected from the pin. The internal signals available
are shown in the software specification.

Figure 23. Block diagram of the Multipath Detector

LEVEL

VDD

DC=1µA

MPIN

BANDPASS

19KHz

GAIN

2 BITS

RECTIFIER

GAIN

2 BITS

-

MPOUT

220nF

to SB

int. INFLUENCE

D97AU880

20/31

Figure 24. ApplicationExample 1

+V

CC

CASS R

CASS L

CDR

CDG

CDL

PHGND

PHONE

=

9V

Note: Bit D7 of ”Bass and Treble Filter characteristics” set to 1

100nF

100nF

100nF

22µF

100nF

220nF

220nF

100nF

PHONE_GND

SOUND

EFFECTS

ACOUTL ACOUTR ACINLACINR

V

S

OUTLF

CASS R

CASS L

CDR

CDG

CDL

TDA7461

PHONE

MPIN MPOUT

UNWEIGHTED

LEVEL

MUXR MUXL

220nF

OUTRF

OUTLR

CREF

OUTLF

OUTRF

OUTLR

OUTRR

MPX

AM

SDA
SCL
SMUTE
LEVEL
GND

TDA7461N

10µF

OUTRR

220nF

MPX

220nF

AM

SDA

SCL

SMUTE

LEVEL

D97AU763A

Figure 25. ApplicationExample 2

+V

CC

CASS R

CASS L

CDR

CDG

CDL

PHGND

PHONE

=

9V

Note: Bit D7of ”Bass and Treble Filter characteristics” set to0

100nF

100nF

100nF

22µF

100nF

220nF

220nF

100nF

PHONE_GND

PRE-SPEAKER

OUTPUT

ACOUTL ACOUTR

V

S

CASS R

CASS L

PHONE

CDR

CDG

CDL

MPIN MPOUT

UNWEIGHTED

LEVEL

ADDITIONAL

INPUT

100nF 100nF

ACINLACINR

TDA7461

MUXR MUXL

220nF

CREF

OUTLF

OUTRF

OUTLR

OUTRR

MPX

AM

SDA
SCL
SMUTE
LEVEL
GND

10µF

OUTLF

OUTRF

OUTLR

OUTRR

220nF

MPX

220nF

AM

SDA
SCL

SMUTE

LEVEL

D97AU764

21/31

TDA7461N

I2C BUS INTERFACE DESCRIPTION
Interface Protocol

The interfaceprotocolcomprises:

-a start condition (S)

/ write transmission)

-a subaddressbyte

-a sequenceof data (N-bytes+ acknowledge)

-a stop condition (P)

-a chip address byte (the LSB bit determinesread

CHIP ADDRESS

MSB LSB MSB LSB MSB LSB

S1000110R/WACK ACK ACKP

D97AU627

S = Start
ACK = Acknowledge
AZ = AutoZero-Remain

SUBADDRESS DATA 1 to DATA n

XI

AZ T A3 A2 A1 A0 DATA

Auto increment

If bit I in the subaddress byte is set to ”1”, the
autoincrementof the subaddressis enabled.

T = Testing
I = Autoincrement
P = Stop
MAX CLOCK SPEED500kbits/s

The transmitted data is automatically updated af­ter each ACK.

Transmission can be repeated without new chip

TRANSMITTED DATA (sendmode)

MSB LSB

XXXXSTSMXX

SM = Soft mute activated
ST = Stereo
X = Not Used

address.

SUBADDRESS (receive mode)

MSB LSB FUNCTION

X AZ T I A3A2A1A0

Input selector

0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1

0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1

0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1

0

Loudness / Auto-Zero

1

Volume

0

Softmute / Beep

1

Bass / Treble Attenuator

0

Bass / Treble Configuration

1

Speaker attenuator LF

0

Speaker attenuator LR

1

Speaker attenuator RF

0

Speaker attenuator RR / Blanktime adjust

1

Stereodecoder

0

Noiseblanker

1

Fieldstrength Control

0

Configuration

1

Stereodecoder Adjustment

0

Testing

1

T = Testmode
I = Autoincrement
AZ = Auto Zero Remain
X = not used

22/31

DATA BYTE SPECIFICATION
Input Selector

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Source Selector

CD

0
0
0
0
1
1
1
1

0
1

1
0
0
1

0
0

:
1
1

For example to select the CD input in quasi-differential mode with gain of 8dB the Data Byte is: 0/01111000

0
0

:
1
1

0
1

:
0
1

0
0
1
1

0
0
1
1
0
0
1
1

1
1
0
0

0

Cassette

1

Phone

0

AM

1

Stereo Decoder

0

Input FM

1

Mute

0

AC inputs

1

CD Mode

CD Full-differential
CD Quasi-diff

AM/FM Mode

AM mono

1

AM stereo

1

AM through Stereodecoder

0

FM- Stereodecoder

0

In-Gain

14dB
12dB
:
2dB
0dB

TDA7461N

Loudness

MSB LSB LOUDNESS

D7 D6 D5 D4 D3 D2 D1 D0

Attenuation

0dB

0
0

:
1
1

0
1

0
1

0
1

1 must be ”1”

Note: The attenuation is specified at high frequencies. Around the center frequency the value is different depending on theprogrammed

attenuation(see Loudness frequency response).

0
0

:
1
1

0
0

:
1
1

0

-1dB

1

:

:

-14dB

0

-15dB

1

Filter

on
off (flat)

Center Frequency

200Hz
400Hz

LoudnessQ

low (1
normal (2

st

order)

nd

order)

23/31

TDA7461N

Mute, Beep and Mixing

MSB LSB MUTE/BEEP/MIXING

D7 D6 D5 D4 D3 D2 D1 D0

Mute

Enable Softmute

0

Disable Softmute

1
0
0
1

0
1

0
1

0

0
0
1
1

Note: for more information to the Stereodecoder-Softmute-Influence please refer to the stereodecoder description.

0
1
0
1

1

1

0
1
0
1

Mute time =0.48 ms
Mute time =0.96 ms
Mute time =40.4 ms
Mute time =324 ms
Stereo Decoder Softmute Influence = off
Stereo Decoder Softmute Influence = on

Beep

Beep Frequency = 600Hz
Beep Frequency = 1.2KHz

Mixing

Mix-Source = Beep
Mix-Source = Phone
Full Mix Signal
Source -12dB + Mix-Signal -2.5dB
Source -6dB + Mix-Signal -6dB
Full Source

Volume

MSB LSB ATTENUATION

D7 D6 D5 D4 D3 D2 D1 D0

Gain/Attenuation

+32dB

0
0

:
0
0
0

:
0
0
0

:
1
1

0
1

Note: It is not recommended to use a gain more than 20dB for system performance reason. In general, the max. gain should be limitedby

softwareto the maximum value,which is needed for the system.

0
0

:
0
0
0

:
0
1
1

:
1
1

0
0

:
0
0
0

:
1
0
0

:
0
0

0
0

:
1
1
1

:
1
0
0

:
1
1

0
0

:
1
1
1

:
1
0
0

:
1
1

0
0

:
0
0
1

:
1
0
0

:
1
1

0

+31dB

1

:

:

+20dB

0

+19dB

1

+18dB

0

:

:

+1dB

1

0dB

0

- 1dB

1

:

:

-78dB

0

-79dB

1

Softstep

Softstep Volume = off
Softstep Volume = on

24/31

TDA7461N

Bass & Treble Attenuation

MSB LSB BASS & TREBLE ATTENUATION

D7 D6 D5 D4 D3 D2 D1 D0

Treble Steps

-14dB

0
0

:
0
0
1
1

:
1
1

0
0

:
0
0
1
1

:
1
1

For example 12dB Trebleand -8dB Bass give the following DATA BYTE: 0 0 1 1 1 0 0 1.

0
0

:
1
1
1
1

:
0
0

0
0

:
1
1
1
1

:
0
0

0
1

:
0
1
1
0

:
1
0

0
0

:
1
1
1
1

:
0
0

0
0

:
1
1
1
1

:
0
0

0
1

:
0
1
1
0

:
1
0

-12dB
:

-2dB
0dB
0dB

+2dB
:
+12dB
+14dB

Bass Steps

-14dB

-12dB

:

-2dB
0dB
0dB

+2dB
:
+12dB
+14dB

Bass & Treble Filter Characteristics

MSB LSB BASS& TREBLEFILTER

D7 D6 D5 D4 D3 D2 D1 D0

Treble

Center Frequency = 10 KHz

0
0
1
1

0
0
1

1
1
0
0
1

0
1

0
1

For example Treble center frequency = 15kHz, Bass center frequency = 100Hz, Bass Q = 1 and DC = 0dB give the following DATA BYTE: 1
0001110

(*) For deeper information see application examples fig. 24 and fig. 25.

1

1
0
1
0
1

1

0
1
0
1
1

0

Center Frequency = 12.5 KHz

1

Center Frequency = 15 KHz

0

Center Frequency = 17.5 KHz

1

Bass

Center Frequency = 60 Hz
Center Frequency = 70 Hz
Center Frequency = 80 Hz
Center Frequency = 100Hz
Center Frequency = 150Hz
Quality factor = 1
Quality factor = 1.25
Quality factor = 1.5
Quality factor = 2
DC-Gain = 0dB
DC-Gain =±4.4dB

AC Coupling (*)

For External Connection
Internally connected

25/31

TDA7461N

Speaker Attenuation (LF, LR, RF, RR)

MSB LSB

D7 D6 D5 D4 D3 D2 D1 D0

0
0

:
1
0
0
1
1
0
0
1
1

11

0
0
1
1

0
1
0
1

0
1

0
0

:
0
0
0
0
0
0
0
0
0
1

0
0

:
1
1
1
1
1
1
1
1
1

0
0

:
0
1
1
1
1
1
1
1
1

0
0

:
1
0
0
0
0
1
1
1
1

Attenuation

0dB

0

-1dB

1

:

:

-23dB

1

-24.5dB

0

-26dB

1

-28dB

0

-30

1

-32dB

0

-35dB

1

-40dB

0

-50dB

1

Speaker Mute
Must be ”1” (except RF, RR speaker; see below)

Blank Time adj. (subaddress speaker RR)
38µs

25.5µs
32µs
22µs

Output selector for pins 15 and 16.

(subaddress spaeaker RF)
Stereodecoder output selected
Input multiplexer output selected

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Stereodecoder

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

01STD Unmuted

STD Muted

0
0
1
1

1 must be ”1”

1
1

0
1

0
1

0
1

0
1
0
1

IN-Gain 11dB
IN-Gain 8.5dB
IN-Gain 6dB
IN-Gain 3.5dB

Forced MONO
MONO/STEREO switch automatically

Pilot Threshold HIGH
Pilot Threshold LOW

Deemphasis 50µs
Deemphasis 75µs

TDA7461N

Noiseblanker

MSB

D7 D6 D5 D4 D3 D2 D1 D0

0
0
0
0
1
1
1
1

0
0
1
1

0
1

0
0
1
1

0
1
0
1

0
1
0
1

0
0
1
1
0
0
1
1

LSB

0
1
0
1
0
1
0
1

FUNCTION

Low Threshold 65mV
Low Threshold 60mV
Low Threshold 55mV
Low Threshold 50mV
Low Threshold 45mV
Low Threshold 40mV
Low Threshold 35mV
Low Threshold 30mV

Noise Controlled Threshold 320mV
Noise Controlled Threshold 260mV
Noise Controlled Threshold 200mV
Noise Controlled Threshold 140mV

Noise blanker OFF
Noise blanker ON

Over deviation Adjust 2.8V
Over deviation Adjust 2.0V
Over deviation Adjust 1.2V
Over deviation Detector OFF

27/31

TDA7461N

FieldstrengthControl

MSB

D7 D6 D5 D4 D3 D2 D1 D0

0
0
1
1

0
0
1
1

0
0
1
1

1
0

0
1

0
1
0
1

0
1
0
1

LSB

0
1
0
1

Noiseblanker Field strength Adj 2.3V
Noiseblanker Field strength Adj 1.8V
Noiseblanker Field strength Adj 1.3V
Noiseblanker Field strength Adj OFF

VSBL at 33% REF 5V
VSBL at 42% REF 5V
VSBL at 50% REF 5V
VSBL at 58% REF 5V

VHCH at 42% REF 5V
VHCH at 50% REF 5V
VHCH at 58% REF 5V
VHCH at 66% REF 5V

VHCL at 17% VHCH
VHCL at 33% VHCH

High cut OFF
High cut ON

FUNCTION

Configuration

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Noise Rectifier Discharge Resistor

R = infinite

0
0
1
1

0
0
1
1

0
1

1 Must be ”1”

0
0
1
1

0
1
0
1

0
1
0
1

0

R = 56kΩ

1

R = 33k

0

R =18k

1

Multipath Detector Bandpass Gain

6dB
16dB
12dB
18dB

Multipath Detector internal influence

ON
OFF

Multipath Detector Reflection Gain

Gain = 7.6dB
Gain = 4.6dB
Gain = 0dB
OFF

Ω

Ω

28/31

StereodecoderAdjustment

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Roll-Off Compensation

not allowed

0
0
0

:
1

:
1

0
0
0

:

1

0
1

0
0
0

:

1

0
0
1

:

1

0
1
0

:

1

0
0
1

:

0

:

1

0

20.2%

1

21.9%

0

:

:

25.5%

0

:

:

31.0%

1

LEVEL Gain

0dB

0.66dB

1.33dB
:
10dB

Temperature compensation at LEVEL input

TC = 0
TC = 16.7mV/K (3300ppm)

Testing

TDA7461N

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Stereodecoder test signals

0

OFF

1

Test signals enabled if bit D5 of the subaddress
(test mode bit)is set to ”1”, too

0
1

0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1

0
1

0
1

Note :This byteis usedfortestingor evaluationpurposes onlyand mustnot beset toothervalues than thedefault ”11111110”in theapplication!

0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1

0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1

0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1

External Clock
Internal Clock

Testsignals at CASS_R

VHCCH
Level intern
Pilot magnitude
VCOCON; VCO ControlVoltage
Pilot threshold
HOLDN
NB threshold
F228
VHCCL
VSBL
not used
not used
PEAK
not used
REF5V
not used

VCO

OFF
ON

Audioprocessortest mode

only ifbit D5 of the subaddress
(test mode bit)is set to ”1”
OFF

29/31

TDA7461N

DIM.

MIN. TYP. MAX. MIN. TYP. MAX.

A 2.65 0.104

a1 0.1 0.3 0.004 0.012

b 0.35 0.49 0.014 0.019

b1 0.23 0.32 0.009 0.013

C 0.5 0.020

c1 45° (typ.)

D 17.7 18.1 0.697 0.713
E 10 10.65 0.394 0.419

e 1.27 0.050

e3 16.51 0.65

F 7.4 7.6 0.291 0.299

L 0.4 1.27 0.016 0.050

S8°(max.)

mm inch

OUTLINE AND

MECHANICAL DATA

SO28

30/31

TDA7461N

Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences
of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is
granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are
subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products
are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.

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31/31