Philips tda8740 DATASHEETS

INTEGRATED CIRCUITS

DATA SH EET

TDA8740; TDA8740H

Satellite sound circuit with noise reduction

Product speciﬁcation Supersedes data of November 1992 File under Integrated Circuits, IC02

Philips Semiconductors

October 1994

Philips Semiconductors Product speciﬁcation

Satellite sound circuit with noise reduction TDA8740; TDA8740H

FEATURES

• Demodulation of main audio signal using wide band PLL (lock range selectable)

• Demodulation of secondary audio signals using wide

APPLICATIONS

• Satellite receivers

• TV sets

• Video recorders.

band PLL

• HF input selection: two-out-of-eight secondary audio signals can be selected

• Noise reduction of the secondary audio signals

• Output selection: stereo, language 1, language 2, main

audio and external

GENERAL DESCRIPTION

The TDA8740; TDA8740H is a multi-function sound IC for use in satellite receivers, television sets and video recorders. The pin numbers given in parenthesis throughout this document refer to the QFP44 package.

• Mute control

• Line outputs (SCART level).

QUICK REFERENCE DATA

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Supply

supply voltage 8 12 13.2 V

Main channel

IN3(rms)

∆f

input sensitivity pin 18 (14) (RMS value) S/N(A) = 40 dB − 1.0 2.0 mV lock range PLL demodulator

either 5.5 − 7.5 MHz or 10.0 − 11.5 MHz

output voltage pin 23 (19) −9 −6 −4 dBV

S/N(A) signal-to-noise ratio A-weighted 62 70 − dB

Secondary channels

IN1,IN2

input sensitivity pins 2, 4, 6, 8, 10, 12, 14 and 16

S/N(A) = 40 dB − 0.8 1.5 mV

(1, 3, 5, 7, 9, 11, 40 and 42) (RMS value) ∆f V

OR,OL

OS1,2

lock range PLL demodulators 6.0 − 8.5 MHz

output voltage pins 24 and 25 (20 and 21) −8 −6 −4 dBV S/N(A) signal-to-noise ratio A-weighted 72 80 − dB

Crosstalk

S/M

M/S

S/S

crosstalk from secondary to main channel − 74 − dB

crosstalk from main to secondary channel − 74 − dB

crosstalk between secondary channels − 74 − dB

October 1994 2

Philips Semiconductors Product speciﬁcation

Satellite sound circuit with noise reduction TDA8740; TDA8740H

ORDERING INFORMATION

TYPE NUMBER

TDA8740 SDIP42 plastic shrink dual in-line package; 42 leads (600 mil) SOT270-1

TDA8740H QFP44

Note

1. When using IR reflow soldering it is recommended that the Drypack instructions in the (order number 9398 510 63011) are followed.

BLOCK DIAGRAM

NAME DESCRIPTION VERSION

(1)

plastic quad ﬂat package; 44 leads (lead length 1.3 mm); body 10 × 10 × 1.75 mm

PACKAGE

“Quality Reference Handbook”

SOT307-2

The pin numbers in parenthesis refer to the QFP44 package.

October 1994 3

Fig.1 Block diagram.

Philips Semiconductors Product speciﬁcation

Satellite sound circuit with noise reduction TDA8740; TDA8740H

PINNING

SYMBOL

SDIP42

QFP44

DESCRIPTION

n.c. 1 39 not connected IN-1A 2 40 intercarrier input A for Channel 1 (left) I

sel 1

3 41 input select switch bit 1 IN-1B 4 42 intercarrier input B for Channel 1 (left) I

sel 2

5 43 input select switch bit 2 IN-1C 6 1 intercarrier input C for Channel 1 (left) MCS 7 2 main channel PLL lock-in range select/disable IN-1D 8 3 intercarrier input D for Channel 1 (left) HFGND 9 4 ground for HF section IN-2A 10 5 intercarrier input A for Channel 2 (right) SCD 11 6 secondary channels PLLs disable IN-2B 12 7 intercarrier input B for Channel 2 (right) MUTE 13 8 mute switch IN-2C 14 9 intercarrier input C for Channel 2 (right) O

sel L

15 10 output select switch bit 1 (left) IN-2D 16 11 intercarrier input D for Channel 2 (right) O

sel R

17 13 output select switch bit 2 (right) IN-3 18 14 intercarrier input for main channel V

REF

D M

C M

INT 26 22 output switch bit 3 (external/internal)

EXT/ EXT

EXT

ATT/REC R

RECT

NR D R

D R

C R

19 15 decoupling capacitor for reference voltage

20 16 de-emphasis capacitor for main channel

21 17 audio pass-through capacitor input for main channel

22 18 positive supply voltage

23 19 main channel output

24 20 right channel output

25 21 left channel output

27 23 external audio input (right)

28 24 external audio input (left)

29 25 attack/recovery capacitor (right)

30 26 rectiﬁer DC decoupling (right)

31 27 noise reduction de-emphasis capacitor (right)

32 28 ﬁxed de-emphasis capacitor (right)

33 29 audio pass-through capacitor input for right channel AFGND 34 30 ground for AF section C

C L

D L

NR D L

RECT C

ATT/REC L

35 31 audio pass-through capacitor input for left channel

36 32 ﬁxed de-emphasis capacitor (left)

37 33 noise reduction de-emphasis capacitor (left)

38 34 rectiﬁer DC decoupling (left)

39 35 attack/recovery capacitor (left)

October 1994 4

Philips Semiconductors Product speciﬁcation

Satellite sound circuit with noise reduction TDA8740; TDA8740H

C C C

DC L DC M DC R

SYMBOL

SDIP42

40 36 DC decoupling capacitor (left)

41 37 DC decoupling capacitor (main)

42 38 DC decoupling capacitor (right)

QFP44

n.c. − 12 not connected n.c. − 44 not connected

DESCRIPTION

October 1994 5

Fig.2 Pin configuration (SDIP42).

Philips Semiconductors Product speciﬁcation

Satellite sound circuit with noise reduction TDA8740; TDA8740H

October 1994 6

Fig.3 Pin configuration (QFP44).

Philips Semiconductors Product speciﬁcation

Satellite sound circuit with noise reduction TDA8740; TDA8740H

FUNCTIONAL DESCRIPTION Satellite sound

The baseband signal coming from a satellite tuner contains the demodulated video signal plus a number of sound carriers to facilitate reception of a PAL/NTSC/SECAM satellite signal.

Nearest to the video signal is the main sound carrier which carries the single channel sound related to the video. This is an FM modulated carrier with a fixed pre-emphasis. The carrier frequency can be in the range of 5.8 to 6.8 MHz.

Additionally, a number of optional secondary sound carriers may be present which can be used for stereo or multi-language sound related to the video, or for unrelated radio sound. These carriers are also FM modulated, but for better sound quality (improved signal-to-noise performance) broadcast satellites (e.g. ‘ASTRA’) use a noise reduction system (adaptive pre-emphasis circuit, combined with a fixed pre-emphasis).

These secondary carrier frequencies can be in the range of 6.30 to 8.28 MHz. The TDA8740; H contains all circuitry for processing the main channel and for two secondary channels, from baseband signal to line (SCART) output drivers. The desired frequencies can be routed to the TDA8740; H via bandpass filters.

Main channel (see Fig.1) The lock-in range of the main channel PLL can be

switched between 5.5 to 7.5 MHz, PLL off and 10.0 to

11.5 MHz using the MCS signal at pin 7 (2) [when pin 7 (2) is at logic 0, being a voltage from 0 to 1.2 V, the lock-in range = 5.5 to 7.5 MHz; when pin 7 (2) is at logic 1, being a voltage from 3.5 V until V

11.5 MHz; when pin 7 (2) is in the mid voltage position, being a voltage from 1.8 to 2.8 V, the main channel PLL is switched off]. The mid voltage position of the MCS pin can also be obtained by a floating MCS pin if the circuit supply voltage Vp is 10.8 to 13.2 V. The voltage on the MCS pin is then determined by the resistor divider at this pin between VP and ground.

If only one fixed carrier frequency for the main channel is to be demodulated (e.g. 6.5 MHz), the lock-in range of the PLL should be switched to 5.5 to 7.5 MHz. The baseband signal is applied to the main channel input, pin 18 (14) via a 6.5 MHz ceramic bandpass filter. Alternatively, if there is a requirement to demodulate different main channel frequencies, these frequencies can be transferred to a fixed intermediate frequency (e.g. 10.7 MHz) using an external mixer and oscillator-frequency synthesizer. In this event the lock-in range of the PLL should be switched to

, the lock-in range = 10.0 to

10.0 to 11.5 MHz. The IF signal is applied to the main channel input, pin 18 (14) via a 10.7 MHz ceramic bandpass filter.

The filtered signal is AC-coupled to a limiter/amplifier and then to a PLL demodulator. The PLL FM demodulator ensures that the demodulator is alignment-free. High gain and DC error signals from the PLL, which are superimposed on the demodulator output, require DC decoupling. A buffer amplifier is used to amplify the signal to the same level as the secondary channels and decouples DC using an electrolytic capacitor connected to pin 41 (37). The demodulator output signal is fed to pin 20 (16) via an internal resistor. The output signal can be de-emphasized by means of this resistor and an external capacitor connected to ground.

Capacitor value = de-emphasis time constant per 1500 (for 50 µs: 33 nF).

From here the signal is fed to the output selectors. The signal is amplified to 500 mV(RMS) (i.e. −6 dBV) in the output amplifiers.

Secondary channels

Up to eight secondary channel inputs are available at pins 2, 4, 6, 8, 10, 12, 14 and 16 (1, 3, 5, 7, 9, 11, 40 and 42). External ceramic bandpass filters tuned to the required secondary sound carrier frequencies route these signals to the inputs.

For stereo applications the TDA8740; TDA8740H contains two identical secondary sound processing channels. For each channel it is possible to select from four inputs (IN-A, IN-B, IN-C and IN-D) using the input selector (see Logic Table 1). With the input switch several stereo signals or languages can be selected for demodulation. It should be noted that the inputs are identical and can be freely interchanged. Secondary Channel 1 will also be referred to as ‘LEFT’ or ‘LANGUAGE 1’ and secondary Channel 2 will also be referred to as ‘RIGHT’ or ‘LANGUAGE 2’.

From the input selector switch the signals are coupled to limiter/amplifiers and then to the PLL demodulators. Processing is similar to the main channel. The demodulator output signal is amplified in a buffer amplifier and DC decoupled using electrolytic capacitors connected to pins 40 (36) (left) and 42 (38) (right). The output level is set with a 220 Ω resistor connected in series with the capacitor.

High frequency components in the amplified PLL output signal are filtered out in the audio LPF block (4th order Butterworth low-pass filter) to prevent unwanted influence on the noise reduction.

October 1994 7

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