SGS Thomson Microelectronics TDA7400 Datasheet



ADVANCED CAR SIGNAL PROCESSOR

FULLY INTEGRATED SIGNAL PROCESSOR
OPTIMIZED FOR CAR RADIO APPLICA­TIONS

FULLY PROGRAMMABLEBY I
INCLUDES AUDIOPROCESSOR, STEREO -

DECODER WITH NOISE BLANKER AND
MULTIPATHDETECTOR

PROGRAMMABLE ROLL-OFF COMPENSA­TION

NO EXTERNALCOMPONENTS

DESCRIPTION

The TDA7400D is the newcomer of the CSPfam­ily introduced by TDA7460/61. It uses the same
innovative concepts and design technologies al­lowing fully software programmability through I
bus and overall cost optimisation for the system
designer.

The device includes an audioprocessor with con­figurable inputs and absence of external compo­nents for filter settings, a last generation
stereodecoder with multipath detector and a so-

2

C BUS

2

C

TDA7400

TQFP44

ORDERING NUMBER: TDA7400

phisticated stereoblend and noise cancellation
circuitry.
Strength pointsof the CSP approachare flexibility
and overall cost/room saving in the application,
combined withhigh performances.

AUDIO PROCESSOR PART

BLOCK DIAGRAM

CDL CDGND CDR

531

CDLOUT

TAPE R

TAPE L

PH+

PH-

MPX

V

2

4

INPUT

10

AM

MULTIPLEXER

+

44

AUTO ZERO

43

8

7

12

27

V

S

41

REF

MUXR

MUXL
FM_R

FM_L

80KHz

LP

SUPPLY

26 42 15 16 14

CREF MPIN

GND

CDROUT

SMUTE

PIL

DET

SOFT

MUTE

DEMODULATOR

+ STEREO

+ STEREO BLEND

VOLUME BASSTREBLE

PILOT

CANCELLATION

PLL

ACOUTL

ACOUTR

DIGITAL CONTROL

ADJUST

MULTIPATH-

DETECTOR

MPOUT LEVEL

25KHz

LP

NOISE

BLANKER

ACINRF

S&H

PULSE

FORMER

ACINRR

3839353422

ACINLF

HIGH

CUT

CONTROL

D

A

ACINLR

3740

OUT LR
OUT LF
OUT RR
OUT RF

I2C BUS

QUAL.

30
32
29
31

23
24
19
18

21

D98AU852B

OUT LR
OUT LF
OUT RR
OUT RF

SCL
SDA
MUX R
MUX L

QUAL

July 1999

1/28

TDA7400

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

S

amb Operating Ambient Temperature Range -40 to 85 °C

T

stg Operating 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 filtersflat) 50 60 dB

ESD

All pins are protectedagainst ESD accordingto the MIL883standard.

PIN CONNECTION

Operating Supply Voltage 10.5 V

=9V 253035mA

S

Stereodecoder + Audioprocessor 45 55 dB

THERMAL DATA

CDR

CDROUT

CDG

CDLOUT

CDL
N.C.

PHONE-

PHONE+

N.C.

AM

N.C.

REF

ACINRF

ACINLF

ACINRR

N.C.

MUXL

ACINLR

MUXR

TAPE R

TAPE L

CREF

V

44 43 42 41 3940 38 37 36 35 34

1
2
3
4
5
6
7
8
9

10

12 13 14 15 16

N.C.

MPX

LEVEL

171118 19 20 21 22

MPIN

MPOUT

N.C.

N.C.

ACOUTL

ACOUTR

QUAL

SMUTE

33
32
31
30
29
28
27
26
25
24
23

D98AU853

N.C.
OUT LF
OUT RF
OUT LR
OUT RR
N.C.
V

S

GND
N.C.
SDA
SCL

Symbol Parameter Value Unit

th-j pins Thermal ResistanceJunction-pins Max 65 °C/W

R

2/28

TDA7400

PIN DESCRIPTION

N. Name Function Type

1 VREF Reference Voltage Output I
2 CREF Reference Capacitor Pin S
3 TAPEL Tape InputLeft I
4 TAPER Tape InputRight I
5 CDR CD Right Channel Input I
6 CDGND CD Input Common Ground I
7 CDL CD Input Left Channel I
8 PH - Differential Phone Input - I

9 PH + Differential Phone Input + I
10 AM AM Input I
11 MPX FM Stereodecoder Input I
12 LEVEL Level InputStereodecoder I
13 MPIN Multipath Input I
14 MPOUT Multipath Output O
15 MUXL Multiplexer Output Left Channel O
16 MUXR Multiplexer Output Right Channel O
17 QUAL Stereodecoder Quality Output O
18 SMUTE Soft Mute Drive I
19 SCL I
20 SDA I
21 GND Supply Ground S
22 VS Supply Voltage S
23 OUTRR Right Rear Speaker Output O
24 OUTLR Left Rear Speaker Output O
25 OUTRF Right Front Spaeaker Output O
26 OUTLF Left FrontSpeaker Output O
27 ACOUTR Pre-speaker AC Output RightChannel O
28 ACOUTL Pre-speaker AC Output Left Channel O

Pin typelegenda: I = Input O = OutputI/O = Input/Output S = Supply nc = not connected

2

C Clock Line I

2

C Data Line I/O

3/28

TDA7400

Input Multiplexer

Quasi-differentialCD and cassettestereoinput
AM monoinput
Phonedifferentialinput
Multiplexer signal after In-Gain available at

separatepins

Treble Control

2nd order frequencyresponse
Center frequencyprogrammablein 4 steps
±15 x 1dB steps

Volume control

1dB attenuator
Max. gain15dB
Max. attenuation79dB

Bass Control

2nd order frequencyresponse
Centerfrequencyprogrammablein 4(5) steps
DC gain programmable
±15 x 1dB steps

Speaker Control

4 independentspeaker controls in 1dB steps
max gain 15dB
max. attenuation79dB

Mute Functions

Direct mute

Digitally controlled softmute with 4 programmable
mute time

DESCRIPTIONOF THE AUDIOPROCESSOR
PART

ELECTRICALCHARACTERISTICS (V

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

unless otherwisespecified).

Symbol Parameter Test Condition Min. Typ. Max. Unit

INPUTSELECTOR

R

in

V

CL

S

IN

IN MIN Min. Input Gain -1 0 1 dB

G

IN MAX Max. Input Gain 13 15 17 dB

G

G

STEP

V

DC

Input Resistance all inputs exceptPhone 70 100 130 K
Clipping Level 2.2 2.6 V
Input Separation 80 100 dB

Step Resolution 0.5 1 1.5 dB
DC Steps AdjacentGain Step -5 0.5 5 mV

to G

G

MIN

MAX

-10 5 10 mV

Ω

RMS

DIFFERENTIAL CD STEREOINPUT

Rin Input Resistance Differential 70 100 130 KΩ

Common Mode 70 100 130 K

CMRR Common Mode Rejection Ratio V

e

N

Output Noise @ Speaker
Outputs

CM=1VRMS

V

CM=1VRMS

20Hz to 20KHz flat; all stages
0dB

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

615

DIFFERENTIAL PHONEINPUT

R

in

CMRR Common Mode Rejection Ratio V

4/28

Input Resistance Differential 40 56 K

CM=1VRMS

V

CM=1VRMS

@ 1KHz 40 70 dB
@ 10KHz 40 60 dB

Ω

V

µ

Ω

TDA7400

ELECTRICALCHARACTERISTICS

(continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

VOLUMECONTROL

GMAX Max Gain 13 15 17 dB

MAX Max Attenuation 70 79 dB

A

A

STEP

E

A

Step Resolution 0.5 1 1.5 dB
Attenuation Set Error G = -20 to20dB -1.25 0 1.25 dB

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

E

T

V

DC

Tracking Error 2dB
DC Steps AdjacentAttenuation Steps 0.1 3 mV

From 0dB to G

MIN

0.5 5 mV

SOFTMUTE

AMUTE Mute Attenuation 80 100 dB

D Delay Time T1 0.48 1 ms

T

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

V

THlow

V

THhigh

R

PD

Low Threshold for SM Pin
High Threshold for SM Pin 2.5 V
Internal Pull-upResistor 70 100 130 K

1

1V

BASSCONTROL

CRANGE Control Range ±13 ±15 ±17 dB

A

STEP

f

C

Q

BASS Quality Factor Q1 0.9 1 1.1

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

DC

Step Resolution 0.5 1 1.5 dB
Center Frequency f

C1

f

C2

f

C3

f

C4

2 1.1 1.25 1.4

Q

3 1.3 1.5 1.7

Q

4 1.8 2 2.2

Q

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

(150)

(2)

110 Hz

DC = on 3.5 4.4 5.5 dB

Ω

TREBLECONTROL

C

RANGE

A

STEP

C Center Frequency fC1 8 10 12 KHz

f

1) The SM pin is activelow (Mute= 0)

2) SeeNote in Programming Part

Control Range

13

±

15

±

Step Resolution 0.5 1 1.5 dB

C2 10 12.5 15 KHz

f

C3 12 15 18 KHz

f

C4 14 17.5 21 KHz

f

17 dB

±

5/28

TDA7400

ELECTRICALCHARACTERISTICS

(continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

SPEAKERATTENUATORS

RIN Input Impedance 35 50 65 KΩ

G

MAX Max Gain 13 15 17 dB

A

MAX

A

STEP

A

MUTE

E

E

V

DC DC Steps Adjacent Attenuation Steps 0.1 5 mV

Max Attenuation -70 -79 dB
Step Resolution 0.5 1 1.5 dB
Output Mute Attenuation 80 90 dB
Attenuation Set Error

2dB

±

AUDIO OUTPUTS

V

CLIP

RL Output LoadResistance 2 KΩ
C

L Output Load Capacitance 10 nF

R

OUT

V

DC

Clipping Level d= 0.3% 2.2 2.6 V

Output Impedance 30 120
DC Voltage Level 4.3 4.5 4.7 V

GENERAL

e

NO

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

d Distortion V

S

C

E

T

Output Noise BW = 20 Hz to 20 KHz

315µV

output muted
BW = 20 Hz to 20 KHz

6.5 15 µV

all gain = 0dB

O =2VRMS 102 110 dB

bass treble at12dB;
a-weighted; V

IN =1VRMS; all stages0dB 0.002 0.1 %

V

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

= 2.6V

O

RMS

96 100 dB

Channel separation Left/Right 80 100 dB
Total Tracking Error AV= 0 to -20dB -1 0 1 dB

A

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

V

BUSINPUTS

V

IL

V

IH

I

IN

V

O Output Voltage SDA

Input Low Voltage d = 0.3% 0.8 V
Input High Voltage 2.5 V
Input Current VIN= 0.4V -5 5

IO = 1.6mA 0.4 V

Acknowledge

RMS

Ω

µ

A

6/28

TDA7400

StereodecoderPart
ELECTRICALCHARACTERISTICS (VS = 9V;deemphasistime constant= 50µs,

MPX

= 500mV(75KHzdeviation), fm= 1KHz, Gv = 6dB,T

V

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

in

R

in

G

MIN

G

MAX

G

STEP

SVRR Supply Voltage Ripple

MPX Input Level Gv = 3.5dB 0.5 1.25 V
Input Resistance 70 100 130 K
Min. Input Gain 1.5 3.5 4.5 dB
Max. Input Gain 8.5 11 12.5 dB
Step Resolution 1.75 2.5 3.25 dB

ripple = 100mV; f = 1KHz 35 60 dB

V

Rejection

α

Max. channel Separation 30 50 dB

THD Total Harmonic Distortion 0.02 0.3 %

S+N

N

Signal plus Noise to Noise
Ratio

A-weighted, S = 2V

MONO/STEREO-SWITCH

VPTHST1 Pilot Threshold Voltage for Stereo, PTH = 1 10 15 25 mV

PTHST0 Pilot Threshold Voltage for Stereo, PTH = 0 15 25 35 mV

V

PTHMO1 Pilot Threshold Voltage for Mono, PTH = 1 7 12 17 mV

V
V

PTHMO0

Pilot Threshold Voltage for Mono, PTH = 1 10 19 25 mV

amb

=27°C; unlessotherwise specified).

rms 80 91 dB

RMS

Ω

PLL

∆f/f Capture Range 0.5 %

DEEMPHASISand HIGHCUT

τHC50

τ

HC75

τ

HC50

τ

HC75 Highcut Time Constant Bit 7, Subadr, 10 = 1,

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

V

LEVEL >> VHCH

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

V

>> V

LEVEL

HCH

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

V

>> V

V

LEVEL

LEVEL

>> V

HCL

HCL

25 50 75

50 75 100

100 150 200

150 225 300 µs

STEREOBLEND-andHIGHCUT-CONTROL

REF5V Internal Reference Voltage 4.7 5 5.3 V

REF5V Temperature Coefficient 3300 ppm

TC

L

Gmin

L

Gmax

L

Gstep

VSBL
VSBL
VSBL

VHCH
VHCH
VHCH

VHCL
VHCL
VHCL

Min. LEVEL Gain -1 0 1 dB
Max. LEVEL Gain 8 10 12 dB
LEVEL Gain Step Resolution 0.3 0.67 1 dB
Min. Voltage for Mono 25 29 33 %REF5V

min

Min. Voltage for Mono 54 58 62 %REF5V

max

Step Resolution 2.2 4.2 6.2 %REF5V

step

min Min. Voltage for NO Highcut 38 42 46 %REF5V
max Min. Voltage for NO Highcut 62 66 70 %REF5V
step Step Resolution 5 8.4 12 %REF5V

Min. Voltage for FULL Highcut 12 17 22 %VHCH

min

Max. Voltage forFULL Highcut 28 33 38 %VHCH

max

Step Resolution 2.2 4.2 6.2 %VHCH

step

s

µ

s

µ

s

µ

7/28

TDA7400

ELECTRICALCHARACTERISTICS

(continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

Carrierand harmonicsuppressionat the output

α19 Pilot Signal f = 19KHz 40 50 dB
α38 Subcarrier f = 38KHz 75 dB

57 Subcarrier f = 57KHz 62 dB

α
α76

Subcarrier f = 76KHz 90 dB

Intermodulation(Note 1)

2f

α

3f

α

= 10KHz, f

mod

= 13KHz, f

mod

= 1KHz 65 dB

spur

= 1KHz 75 dB

spur

TrafficRatio (Note 2)

57 Signal f = 57KHz 70 dB

α

SCA- SubsidiaryCommunicationsAuthoorization(Note 3)

α67 Signal f = 67KHz 75 dB

ACI - AdjacentChannel Interference(Note 4)

114 Signal f = 114KHz 95 dB

α
α190 Signal f = 190KHz 84 dB

Notes to the characteristics:

V

1. IntermodulationSuppression: α2 =

α3 =

measured with: 91%pilot signal;fm =10kHz or13kHz.

O(signal)(at1KHz

V

O(spurious)(at

V

O(signal)(at1KHz)

V

O(spurious)(at

1KHz)

1KHz)

)

=(2 x 10KHz)−19KHz

;f

s

;f

=(3 x 13KHz)−38KHz

s

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

V

α57(

V.W>F.

)=

V

O

(spurious)(

O(signal)(at1KHz)

+⁄

1KHz

at

23KHz)

−

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

V

α67=

4. ACI ( Adjacent Channel Interference): α114 =

α190 =

O(signal)(at1KHz)

V

O

(spurious)(

V

O(signal)(at1KHz

V

O(spurious)(at

V

O(signal)(at1KHz)

V

O(spurious)(at

9KHz)

at

4KHz)

4KHz)

2 x 38KHz)−67KHz

F

;

=(

S

)

=110KHz− (3x38KHz)

;F

S

=186KHz− (5x38KHz)

;F

S

measured with: 90% mono signal; 9% pilotsignal; fm =1kHz; 1% spurious signal ( fs =110kHz or 186kHz, unmodulated).

8/28

NOISE BLANKER PART

TDA7400

internal 2ndorder 140kHz high passfilter
programmabletriggerthreshold
trigger threshold dependent on high frequency

noise withprogrammable gain

additional circuits for deviation and field-

very low offset current during hold time due to
opamps wMOSinputs

four selectablepulse suppressiontimes
programmable noise rectifier charge/discharge

current

strength dependenttrigger adjustment

ELECTRICALCHARACTERISTICS (continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

TR

Trigger Threshold

VTRNOISE Noise ControlledTrigger

Threshold

V

RECT

V

RECT DEV

Rectifier Voltage V

deviation dependent
rectifier Voltage

VRECT FS Fieldstrength Controlled

Rectifier Voltage

T

V

RECTADJ

S

Suppression Pulse
Duration

5)

Noise Rectifier
discharge adjustment

SR

PEAK Noise Rectifier Charge Signal PEAKin

(c) = by design/characterization functionally guaranteed through dedicated test mode structure

0) 1)

meas. with V

= 0.9V NBT = 111 (c) 30 (c) mV

PEAK

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

2)

meas. with VPEAK = 1.5V NCT = 00 (c) 260 (c) mVOP

NCT = 01 (c) 220 (c) mV
NCT = 10 (c) 180 (c) mV
NCT = 11 (c) 140 (c) mV

= 0mV NRD6)= 00 0.5 0.9 1.3 V

MPX

V

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

V

MPX = 200mV; 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)
Signal HOLDN

in Testmode

FSC = 11 0.5 0.9(off) 1.3 V
FSC = 10 0.9 1.4 1.5 V
FSC = 01 1.7 1.9 2.3 V
FSC = 00 2.1 2.4 3.1 V
BLT = 00 TBD 38 TBD
BLT = 10 TBD 32 TBD
BLT = 01 TBD 25.5 TBD µs

Signal PEAK in

6)

Testmode

Testmode

BLT = 00 TBD 22 TBD µs
NRD = 00
NRD = 01
NRD = 10
NRD = 11

PCH = 0
PCH = 1

6)

(c) 0.3 (c) V/ms

6)

(c) 0.8 (c) V/ms

6)

(c) 1.3 (c) V/ms

6)

(c) 2.0 (c) V/ms

7)

(c) 10 (c) mV/µs

7)

(c) 20 (c) mV/µs

OP

OP
OP
OP
OP

OP
OP
OP

OP
OP
OP
OP

s

µ

s

µ

9/28

TDA7400

ELECTRICALCHARACTERISTICS

(continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

ADJMP

Noise Rectifier adjustment
through Multipath

8)

Signal PEAK in
Testmode

MPNB = 00
MPNB = 01
MPNB = 10
MPNB = 11

0) All Thresholdsare measuredusinga pulsewithTR =2µs, THIGH=2µs and TF =10µs. Therepetitionrate must notincrease the PEAKvoltage.

1) NBT represents the Noiseblanker Byte bits D

2) NAT represents the Noiseblanker Byte bit pairD

3) OVDrepresents theNoiseblanker Byte bit pairD

4) FSC represents the FieldstrengthByte bitpair D

5) BLT represents theSpeaker RR Byte bit pair D

6) NRD represents theConfiguration-Byte bit pair D

7) PCH represents the Stereodecoder-Byte bit D

8) MPNBrepresents theHighCut-Byte bit D

V

IN

7 and the Fieldstrength-Byte D7 for the noiserectifier multipath adjustment

forthe noise blanker trigger threshold

2,D0

for thenoise controlled triggeradjustment

4,D3

for theover deviation detector

7,D6

forthe fieldstrengthcontrol

1,D0

,D6for the blanktime adjustment

7

1,D0 forthe noise rectifier discharge-adjustment

5 forthe noise rectifier charge-current adjustment

8)

(c) 0.3 (c) V/ms

8)

(c) 0.5 (c) V/ms

8)

(c) 0.7 (c) V/ms

8)

(c) 0.9 (c) V/ms

V

OP

DC

D97AU636

T

RTHIGH

Figure 1. TriggerThreshold vs.VPEAK

VTH

8 STEPS

65mV

30mV

MIN. TRIG. THRESHOLD

0.9V

D97AU648

NOISE CONTROLLED

TRIG. THRESHOLD

1.5V

V

PEAK(V)

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

T

F

Time

Figure 2. DeviationControlled TriggerAdjust-

ment

V

PEAK

)

(V

OP

00

2.8

2.0

1.2

0.9

D97AU649

20

32.5 45 75

01

10

DETECTOR OFF (11)

DEVIATION(KHz)

10/28

Figure 3. FieldstrengthControlled TriggerAdjustment

V

PEAK

MONO STEREO

»3V

NOISE

ATC_SB OFF(11)

2.4V(00)

1.9V(01)

1.4V(10)

TDA7400

0.9V

E’

MultipathDetector

Internal19kHz band pass filter

noisy signal goodsignal

D97AU650

two pin solution fully independent usable for
externalprogramming

selectable internalinfluence on Stereoblend

Programmableband pass andrectifier gain

ELECTRICALCHARACTERISTICS (continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit

CMP Center Frequency of Multipath-

f

Bandpass

G

BPMP

G

RECTMP

I

CHMP

I

DISMP

Bandpass Gain bits D2,D1configuration byte = 00 6 dB

Rectifier Gain bits D7,D6configuration byte = 00 7.6 dB

Rectifier Charge Current bit D5configuration byte = 0 0.5

Rectifier Discharge Current 0.5 1 1.5 mA

stereodecoder locked on Pilottono 19 KHz

bits D
bits D
bits D

bits D
bits D
bits D

bit D

configuration byte = 10 12 dB

2,D1

configuration byte = 01 16 dB

2,D1

configuration byte = 11 18 dB

2,D1

configuration byte = 01 4.6 dB

7,D6

configuration byte = 10 0 dB

7,D6

,D6configuration byte = 11 off dB

7

configuration byte = 1 1.0

5

A

µ

A

µ

Quality Detector

Symbol Parameter Test Condition Min. Typ. Max. Unit

A Multipath Influence Factor bit D

bit D

High-Cut byte +

7

Fieldstrength byte +

7

00
01
10
11

0.7

0.85

1.00

1.15

11/28

TDA7400

Input Multiplexer

CD quasi differential
Cassettestereo
Phonedifferential
AM mono
Stereodecoderinput.

Input stages

Most of the input stages have remainedthe same
as in preceeding ST audioprocessorswith excep­tion of the CD inputs(see figure 4).
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 common­mode rejectioneven with those CD players.

The output of the Cd stage is permanently avail­able of the Cd out-pins

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 amplifiedto the output.

To avoid that effect a special offset cancellation
stage calledAutoZerois implemented.

This stage is located before the volume-block to
eliminate all offsets generated by the Stereode­coder, the Input Stage and the In-Gain (Please
notice that externally generatedoffsets, e.g. gen-

erated through the leakage current of the cou­pling capacitors,are not cancelled).

The auto-zeroing is started every time the DATA­BYTE 0 is selected and takes a time of max.

0.3ms. To avoid audible clicks the audioproces­sor is muted before the volume stage during this
time.

AutoZeroRemain

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 undesired mute
would appear at the outputs. For such applica­tions the TDA7400D 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.

MultiplexerOutput

The output signal of the Input Multiplexer is avail­able at separate pins (please see the Blockdia­gram). This signalrepresents the input signal am­plifier by the In Gain stage and is also going into
the Mixer stage.

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 criticalregions (see fig­ure 5).

2

For timing purposes the Bit 3 of the I

C bus out-

put register is set to 1 from the startof mutingun-

C

Figure 4. Inputstages

12/28

CD+

CD-

PHONE+

PHONE-

CASSETTE

AM

MPX

100K

100K

100K

100K

100K

1

1

15K 15K

+

-

15K 15K

15K 15K

+

-

15K 15K

STEREODECODER

CD OUT

IN GAIN

D98AU854A

TDA7400

Figure 5. Softmute Timing

1

EXT.

MUTE

+SIGNAL

REF

-SIGNAL

1

2

C BUS

I

OUT

Note: Pleasenotice that a startedMute action is always terminated
and could not beinterrupted by a change of the mute signal.

D97AU634

Time

til the end of demuting.

Bass

There are four parameters programmable in the
bass stage: (seefigs 6, 7, 8, 9):

Attenuation

Figure 6 shows the attenuation as a function of
frequency at a center frequency at a center fre­quency of 80Hz.

Central Frequency

Figure 7 shows the four possible center frequen­cies 60,70,80and 100Hz.

Quality Factors

Figure 8 shows the four possible qualityfactors 1,

1.25, 1.5 and 2.

DC Mode

In this mode the DC gain is increased by 5.1dB.
In addition the programmedcenter frequencyand
quality factor is decreasedby 25% which can be
used to reach alternative center frequencies or
qualityfactors.

TREBLE

There are two parameters programmable in the
treble stage (seefigs 10, 11):

Attenuation

Figure 10 shows the attenuation as a function of
frequency at a centerfrequencyof 17.5KHz.

Center Frequency

Figure 11 shows the four possible Center Fre­quency (10, 12.5,15 and17.5kHz).

Speaker Attenuator

The speaker attenuators have exactely the same
structureand rangelike the Volume stage.

FUNCTIONAL DESCRIPTION OF STEREODE­CODER

The stereodecoder part of the TDA7400D (see
Fig. 12) contains all functions necessary to de­modulate the MPX signal like pilot tone depend­ent MONO/STEREO switching as well as
”stereoblend”and ”highcut”functions.

Figure 6. BassControl @ 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 7. BassCenter @ 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

13/28

TDA7400

Figure 8. BassQuality factors @ Gain = 14dB,

fc = 80Hz

15.0

12.5

10.0

7.5

5.0

2.5

0.0

10.0 100.0 1.0K 10.0K

Figure 10. TrebleControl @ fc = 17.5KHz

15 . 0

10 . 0

5.0

Figure 9. Bassnormal and DC Mode @ Gain =

14dB, fc = 80Hz

15.0

12.5

10.0

7.5

5.0

2.5

0.0

10.0 100.0 1.0K 10.0K

Note: In general the center frequency, Q and DC-mode can be set
independently. Theexceptionfromthis ruleisthe mode(5/xx1111xx)
where thecenter frequency is set to 150Hz insteadof 100Hz.

Figure 11. TrebleCenter Frequencies

@ Gain = 14dB

15.0

12.5

10.0

0.0

-5. 0

-10.0

-15.0

10.0 100.0 1.0K 10.0K

StereodecoderMute

The TDA7400D has a fast and easy to control
RDS mute function which is a combinationof the

7.5

5.0

2.5

0.0

10.0 100.0 1.0K 10.0K

audioprocessor’s 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

14/28

TDA7400

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 conditionsimply the unmute commandmust
be sent: the stereodecoder is unmuted immedi­ately and the audioprocessor is softly unmuted.
Fig. 13 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-ohmicmutestate.

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

Ingain + Infilter

The Ingain stage allows to adjust the MPX signal
to a magnitude of about 1Vrms internally which is
the recommendedvalue. The 4th order input filter
has a corner frequency of 80KHz and is used to

attenuate spikes and nose and acts as an anti al­lasing filter for the following switch capacitor fil­ters.

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
TDA7400D offers an I2C bus programmable roll­off adjustment which is able to compensate the
lowpass behaviour of the tuner section. If the
tuner attenuation at 38kHz is in a range from

13.8% to 24.6% the TDA7400D needs no exter­nal network in front of the MPX pin. Within this
range an adjustment to obtain at least 40dB
channelseparationispossible.

The bits for this adjustment are located together
with the fieldstrengthadjustmentin one byte. This
gives the possibility to perform an optimization
step during the production of the carradio where
the channel separation and the fieldstrength con­trol are trimmed.
The setup of the Stereoblend characteristics
which is programmable in a wide range is de­scribedin 2.8.

Figure 12. BlockDiagram of the Stereodecoder

DEMODULATOR

- PLOT

- ROLL-OFF

- LP 25KHz

MPX

100K

INGAIN

3.5 ... 11dB
STEP 2.5dB

D98AU855

INFILTER

LP 80KHz

4.th ORDER

PLL +

PILOT-DET.

F19
F38

STEREO

NOISE BLANKER

HOLDN

NOISE

CANC

COMP.

SB CONTROL

-

MULTIPATH

DETECTOR

MPLEVELOUT

t=50 or 75µs

REF 5V
VSBL

MPINFL

LEVEL INTERN

DEEMPHASIS

+ HIGHCUT

HC

CONTROL

D

MP_OUT

MP_IN

A

LEVEL INPUT

LP 2.2KHZ

1.thORDER
GAIN 0..10dB

QUALITY DETECTOR

FM_L

FM_R

VHCCH
VHCCL

LEVEL

+

QUAL

15/28

TDA7400

Figure 13. SignalsDuring Stereodecoder’s

Softmute

SOFTMUTE

COMMAND

t

STD MUTE

t

V

O

D97AU638

t

Deemphasisand Highcut.

The lowpass filter for the deemphasis allows to
choose between a time constant of 50µs and
75µs (bit D

7

, Stereodecoderbyte).

The highcut control range will be in both cases

τ

HC

=2⋅τ

. Inside the highcut control range

Deemp

(between VHCH and VHCL) the LEVEL signal
is converted into a 5 bit word which controls the
lowpass time constant between τ

τ

. Thereby the resolution will remain always

Deemp

Deemp

...3⋅

5 bits independently of the absolute voltage
range between theVHCHand VHCL values.

2

The highcut function can be switched off by I
bus (bit D

7

, Fieldstrengthbyte setto ”0”).

C

The setup of the highcut characteristics is de­scribed in 2.9.

Figure 14. InternalStereoblendCharacteristics

LEVEL Input and Gain

To suppress undesired high frequency modula­tion on the highcut and stereoblend function the
LEVELsignal is lowpass filtered firstly.

The filter is a combination of a 1st order RC low­pass at 53kHz (working as anti-aliasing filter)and
a 1st-orderswitched capacitor lowpassat 2.2kHz.
The second stage is a programmable gain stage
to adapt the LEVELsignal internallyto different IF
device(see Testmode section5 LEVELINTERN).

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.

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 detectorenables
the demodulation if the pilot tone reaches the se­lected pilot tone threshold V

PTHST. Two different

thresholdsare available.The detectoroutput (sig­nal STEREO, see blockdiagram) can be checked
by reading the status byte of the TDA7400D via

2

C bus.

I

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 and as input for the multipath
detector. These additional functions are de­scribed in sections3.3 and 4.

16/28

StereoblendControl

The stereoblend control block converts the inter­nal LEVEL voltage (LEVEL INTERN) into an de­modulatorcompatible analog signalwhichis 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 programmedbetween 29.2% and 58%, of
REF5Vin 4.167% steps(see figs. 11, 12).

To adjustthe external LEVELvoltageto the inter­nal range two values must be defined: the LEVEL
gain L

and VSBL (see fig. 12). To adjust the

G

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

has to be de-

G

fined. The following equation can be used to esti­mate the gain:

Figure 15. RelationBetweenInternaland ExternalLEVELVoltageand Setup ofStereoblend

TDA7400

INTERNAL

VOLTAGES

REF 5V

VSBL

SETUP OF VST

LEVEL INTERN

LEVEL

VSTVMO

t

FIELDSTRENGHT VOLTAGE

Figure 16. HighcutCharacteristics

LOWPASS

TIME CONSTANT

3•τ

Deemp

τ

Deemp

FIELDSTRENGHTVHCHVHCL

=

L

G

Fieldstrength

D97AU640

REF 5 V

voltage[STEREO]

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

The MONO voltage VMO (0dB channel separa­tion) can be choosenselecting VSBL
All necessary internal reference voltages like
REF5V are derived from a bandgap circuit.
Therefore they have a temperature coefficient
near zero. This is usefulif the fieldstrength signal
is also temperaturecompensated.

But mostIF devicesapply a LEVEL voltagewith a
TC of 3300ppm. The TDA7400D offers this TC
for the reference voltages, too. The TC is select-

7

able with bit D

of the ”stereodecoderadjustment”

byte.

Highcut Control

The highcut control setup is similar to the

INTERNAL

VOLTAGES

REF 5V

VSBL

58%
50%
42%
33%

D97AU639

SETUP OF VMO

VMO FIELDSTRENGHT VOLTAGE

LEVEL INTERN

VST

t

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, 22, 28 or 33% ofVHCH(see fig. 21).

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 outputof the stereodecoderis held
at the actual voltage for a time between 22 and
38µs (programmable).

The block diagram of the noiseblankeris given in
fig.17.

In a firststage 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 biasingcircuit.

TriggerPath

The incoming MPX signal is highpass filtered,
amplified and rectified. This second order high­pass-filterhas a cornerfrequency 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 resulting voltage can be adjusted by use of
the noise rectifierdischarge current.

The PEAKvoltage is fed to a thresholdgenerator,
which adds to the PEAK voltage a DC depend­ent threshold VTH. Both signals, RECT and

17/28

TDA7400

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 selectedduration.

Automatic NoiseControlled ThresholdAdjust­ment (ATC)

There are mainly two independent possibilities for
programmingthe triggerthreshold:

a the low thresholdin 8 steps(bits D

0 toD2 of

the noiseblankerbyte)

b the noise adjustedthreshold in 4 steps

3

(bits D

andD4of 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 programmablein 4 steps (see fig. ...).

AUTOMATIC THRESHOLD CONTROL MECHA­NISM

noisy is fixed by the RF part. Therefore also the
starting point of the normal noise-controlled trig­ger adjustment is fixed (fig. 11). 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 occuresfor the MPX signal often shows
distortion in this range which can be avoided
even if usinga 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

0 and D1 of the fieldstrengthcontrolbyte.

D

Over DeviationDetector

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 thresholdadjustment.

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

6

with the bits D

and D7of the stereodecoderbyte

(the first stepturns off thedetector,see fig. 15).

Automatic Threshold Control by the
StereoblendVoltage

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

The point where the MPX signal starts to become

Figure 17. BlockDiagramof theNoiseblanker

MPX

MPX CONTROL

RECTIFIER

LOWPASS

D98AU856

RECT

FUNCTIONAL DESCRIPTION OF THE MULTI­PATH DETECTOR

Using the internal multipath detector the audible
effects of a multipathcondition can be minimized.
A multipath condition is detected by rectifying the
19kHz spectrumin the fieldstrengthsignal.
An external capacitor is used to define the attack
and decay times (see block diagram fig. 23). the

+

-

VTH

+

PEAK

+

MONOFLOP HOLDN

THRESHOLD

GENERATOR

ADDITIONAL
THRESHOLD

CONTROL

18/28

Figure 18. BlockDiagramof theMultipathDetector

TDA7400

LEVEL

CHARGE

1 bit

MP_IN

BANDPASS

19KHz

GAIN

2 BITS

RECTIFIER

GAIN

2 BITS

MPOUT pin is used as detector outputconnected
to a capacitor of about 47nF and additionally the
MPIN pin is selected to be the fieldstrengthinput.
Using the configuration an external adaptation to
the user’s requiremetis givenin fig.25.

Selecting the ”internal influence” in the configura­tion byte, the channel separation is automatically
reduced during a multipathcondition according to
the voltage appearing at the MP_OUT pin. A
possible applicationis shown infig. 26.

Programming

To obtain a good multipath performancean adap­tation is necessary. Therefore tha gain of the
19kHz bandpass is programmable in four steps
as wellas the rectifier gain. The attackand decay
times can be set bythe external capacitorvalue.

QUALITY DETECTOR

The TDA7400D offers a quality detector output
which gives a voltagerepresenting the FM recep­tion conditions. To calculate this voltage the MPX
noise and the multipath detector output are
summed accordingto the followingformula:

Quality= 1.6 (V

-0.8V)+a (REF5V-V

noise

MPOUT

)

-

VDD

int. INFLUENCE

MPOUT

47nF

D98AU857

to SB

tional influences. The factor ”a” can be pro­grammed from 0.7 to 1.15. the output is a low im­pedance output able to drive external circuitry as
well as simply fed to an A/D converter for RDS
applications.

TEST MODE

During the test mode which can be activated by
setting bit D

0 of the testing byte and bit D5 of the

subaddress byte to ”1” several internal signals
are available attheCASSR pin.

During this mode theinputresistor of 100kOhm is
disconnected from the pin. The internal signals
availableare shownin the softwarespecification.

2

I

C BUS INTERFACEDESCRIPTION

Interface Protocol

The interfaceprotocol comprises:

-a start condition(S)

-a chip addressbyte (the LSB bitdetermines read
/ write transmission)

-a subaddressbyte

-a sequence of data(N-bytes+ acknowledge)

-a stop condition(P)

The noise signal is the PEAK signal withoutaddi-

19/28

TDA7400

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 SPEED 500kbits/s

The transmitted data is automatically updated af­ter each ACK. Transmission can be repeated
without newchip address.

SUBADDRESS

(receivemode)

TRANSMITTED DATA

MSB LSB

XXXXSTSMXX

SM = 1 Soft mute activated
ST = 1 Stereomode
X = Not Used

(sendmode)

MSB LSB FUNCTION

I3 I2 I1 I0 A3 A2 A1 A0

AntiRadiation Filter

0
1

0
1

0
1

0
1

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

off
on

AutoZero Remain

off
on

Testmode

off
on

Auto Increment Mode

off
on

Databyte Addressing

Input Selector

0

Volume

1

Treble

0

Bass

1

Speaker attenuator LF

0

Speaker attenuator RF

1

Speaker attenuator LR

0

Speaker attenuator RR

1

SoftMute / Bass Prog.

0

Stereodecoder

1

Noiseblanker

0

High Cut Control

1

Fieldstrength & Quality

0

Configuration

1

Stereodecoder Adjustment

0

Testing

1

20/28

DATA BYTE SPECIFICATION
Input Selector(subaddress0H)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Source Selector

CD

0
0
0
0
1
1
1
1

0
0

:
1
1

0
1

0
0

:
1
1

0
0

:
1
1

0
1

:
0
1

0
0
1
1
0
0
1
1

0

Cassette

1

Phone

0

AM

1

Stereo Decoder

0

AC Inputs Front

1

Mute

0

AC inputs Rear

1

In-Gain

15dB
14dB
:
1dB
0dB

Coupl.Front Speaker

external
internal

TDA7400

Volume and SpeakerAttenuation (subaddress1H, 4H, 5H, 6H, 7H)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

1

:
1
1

1

:
1
0
0
0

:
0
0

:
0
0

X 1 1 X X X X X Mute

0

:
0
0

0

:
0
0
0
0

:
0
0

:
1
1

0

:
0
0

0

:
0
0
0
0

:
0
0

:
0
0

1

:
1
1

0

:
0
0
0
0

:
0
1

:
0
0

1

:
0
0

1

:
0
0
0
0

:
1
0

:
1
1

1

:
0
0

1

:
0
0
0
0

:
1
0

:
1
1

1

:
0
0

1

:
0
0
0
0

:
1
0

:
1
1

1

:
1
0

+15dB

1

:

:

+1dB

1

0dB

0

0dB

0

-1dB

1

:

:

-15dB

1

-16dB

0

:

:

-78dB

0

-79dB

1

not used configurations

21/28

TDA7400

Treble Filter (subaddress2H)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Treble Steps

-15dB

0
0

:
0
0
1
1

:
1
1

0
0
1
1

0
1

0
1
0
1

0
0

:
1
1
1
1

:
0
0

0
0

:
1
1
1
1

:
0
0

0

-14dB

1

:

:

-1dB

0

0dB

1

0dB

1

+1dB

0

:

:

+14dB

1

+15dB

0

Treble Center Frequency

10.0KHz

12.5KHz

15.0KHz

17.5KHz

Coupl.Rear Speaker

external (AC)
internal

Bass Filter (subaddress3H)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Bass Steps

-15dB

0
0

:
0
0
1
1

:
1
1

0
0
1
1

0
1

0
1
0
1

0
0

:
1
1
1
1

:
0
0

0
0

:
1
1
1
1

:
0
0

0

-14dB

1

:

:

-1dB

0

0dB

1

0dB

1

+1dB

0

:

:

+14dB

1

+15dB

0

Bass Q-Factor

1.0

1.25

1.50

2.0

Bass DC Mode

off
on

22/28

Soft Mute and Bass Programming(subaddress8H)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Mute

0

Enable Soft Mute

1

Disable Soft Mute
Mutetime = 0.48ms
Mutetime = 0.96ms
Mutetime = 40.4ms
Mutetime = 324ms
Stereodecoder Soft Mute Influence= on
Stereodecoder Soft Mute Influence= off

Bass Center Frequency

Center Frequency = 60 Hz
Center Frequency = 70 Hz
Center Frequency = 80 Hz
Center Frequency = 100Hz
Center Frequency = 150Hz (1)

Noise Blanker Time

Center Frequency = 38µs
Center Frequency = 25.5µs
Center Frequency = 32µs
Center Frequency = 22µs

0
0
1
1
1

0
0
1
1

(1) Only for Bass Q-Factor = 2.0

0
1
0
1

0
1
0
1
1

0
0
1

1
0
1

0
1
0
1

TDA7400

Stereodecoder

(subaddress9H)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

0

STD Unmuted

1

STD Muted

0

1

1 must be ”1”

0
1

0
1

0
1

0
1

1
0

In Gain 8.5dB
In Gain 6dB
others combinations not used

Forced Mono
Mono/Stereo switch automatically

Noiseblanker PEAK charge current low
Noiseblanker PEAK charge current high

Pilot Threshold HIGH
Pilot Threshold LOW

Deemphasis 50µs
Deemphasis 75µs

23/28

TDA7400

Noiseblanker(subaddressAH)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Low Threshold 65mV

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

0

Low Threshold 60mV

1

Low Threshold 55mV

0

Low Threshold 50mV

1

Low Threshold 45mV

0

Low Threshold 40mV

1

Low Threshold 35mV

0

Low Threshold 30mV

1

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

High Cut (subaddressBH)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

0

High Cut OFF

1

High Cut ON

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

Max. High Cut 2dB
Max. High Cut 5dB
Max. High Cut 7dB
Max. High Cut 10dB

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

VHCL at 16.7% VHCH
VHCL at 22.2% VHCH
VHCL at 27.8% VHCH
VHCL at 33.3% VHCH

Strong Multipath influence on PEAK 18K

OFF
ON (18K Dischargeif V

MPOUT

<2.5V)

24/28

FieldstrengthControl (subaddressCH)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

VSBL at 29% REF5V

0

0

0

0

1

1

1

1

0
0
1
1

0
0
1
1

0
1

0
1
0
1

0
1
0
1

0
0
1
1
0
0
1
1

0

VSBL at 33% REF5V

1

VSBL at 38% REF5V

0

VSBL at 42% REF5V

1

VSBL at 46% REF5V

0

VSBL at 50% REF5V

1

VSBL at 54% REF5V

0

VSBL at 58% REF5V

1

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

Quality Detector Coefficient a = 0.7
Quality Detector Coefficient a = 0.85
Quality Detector Coefficient a = 1.0
Quality Detector Coefficient a = 1.15

Multipath off influenceon PEAK discharge

-1V/ms (at MPout= 2.5V

TDA7400

Configuration

(subaddressDH)

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Noise Rectifier Discharge Resistor

R = infinite

0
0
1
1

0
1
0
1

0
1

0
1

0
0
1
1

0
1
0
1

0

0

1

1

0

R = 56k

1
0
1

Ω

R = 33kΩ
R =18kΩ

Multipath Detector Bandpass Gain

6dB
12dB
16dB
18dB

Multipath Detector internal influence

ON
OFF

Multipath Detector Charge Current 0.5µA
Multipath Detector Charge Current 1µA

Multipath Detector Reflection Gain

Gain = 7.6dB
Gain = 4.6dB
Gain = 0dB
disabled

25/28

TDA7400

StereodecoderAdjustment(subaddress EH)

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

1 must be ”1”

0
0
0

:

1

0
0
1

:

1

0
1
0

:

1

0
0
1

:

0

:

1

Testing (subaddressFH)

0
1
0

:

0

:

1

19.6%

21.5%
:

25.3%
:

31.0%

Level Gain

0dB

0.66dB

1.33dB
:
10dB

MSB LSB FUNCTION

D7 D6 D5 D4 D3 D2 D1 D0

Stereodecoder test signals

OFF

0

Test signals enabled ifbit D5 of the subaddress

1

(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 byte is used fortestingor evaluationpurposes only andmust not besettoothervalues thanthedefault ”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 Control Voltage
Pilot threshold
HOLDN
NB threshold
F228
VHCCL
VSBL
not used
not used
PEAK
not used
REF5V
not used

VCO

OFF
ON

Audioprocessor test mode

enabled if bit D5 of the subaddress
(test mode bit) is set to ”1”
OFF

26/28

TDA7400

DIM.

mm inch

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

A 1.60 0.063

A1 0.05 0.15 0.002

0.006

A2 1.35 1.40 1.45 0.053 0.055 0.057

B 0.30 0.37 0.45 0.012 0.014 0.018

C 0.09 0.20 0.004

0.008

D 12.00 0.472
D1 10.00 0.394
D3 8.00 0.315

e 0.80 0.031

E 12.00 0.472
E1 10.00 0.394
E3 8.00 0.315

L 0.45 0.60 0.75 0.018 0.024 0.030

L1 1.00 0.039

K 0°(min.),3.5°(typ.),7°(max.)

OUTLINE AND

MECHANICAL DATA

TQFP44 (10 x 10)

D

D1

A1

2333

34

B

44

1

e

11

TQFP4410

22

E

E1

12

L

0.10mm
.004

Seating Plane

B

K

A

A2

C

27/28

TDA7400

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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 publicationsupersedes and replaces all information previously supplied. STMicroelectronics products
are not authorized for use as critical components in lifesupport devices or systems without express written approval of STMicroelectronics.

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