Philips TDA8745, TDA8745H Datasheet

INTEGRATED CIRCUITS

DATA SHEET

TDA8745

Satellite sound receiver with

I2C-bus control

Preliminary specification

1996 Mar 11

Supersedes data of 1995 Mar 08

File under Integrated Circuits, IC02

Philips Semiconductors	Preliminary specification
Satellite sound receiver with I2C-bus control	TDA8745

FEATURES

·On-chip frequency synthesizer and mixer:

–tuning range 4 to 9.77 MHz

–reference oscillator 4 MHz (using a crystal or 4 MHz frequency source)

·IF input switches allowing selection of various IF bandwidths (wide or narrow)

·Demodulation of two audio signals by wide band Phase-Locked Loops (PLLs)

·Audio level control after PLL (modulation depth setting)

·Noise Reduction (NR) bypass for use with main audio signals

·Left, right and mono output [1¤2(l + r)] on SCART level

·External audio inputs (for decoder connection)

·Selectable de-emphasis (DEEM) 50 ms, 75 ms, J17 and flat response

·I2C-bus control of all functions

·Two selectable addresses

·Carrier presence detector with automatic mute option.

ORDERING INFORMATION

APPLICATIONS

·Satellite receivers

·TV sets

·Video recorders.

GENERAL DESCRIPTION

The TDA8745 is the successor of the TDA8740 and TDA8741. The device contains the functionality of the TDA8740 and TDA8741 together with a synthesizer, mixer and I2C-bus control.

The pin numbers mentioned in this publication refer to the SDIP42 package; unless otherwise indicated.

TYPE		PACKAGE
NUMBER	NAME	DESCRIPTION	VERSION
TDA8745	SDIP42	plastic shrink dual in-line package; 42 leads (600 mil)	SOT270-1
TDA8745H	QFP44	plastic quad flat package; 44 leads (lead length 1.3 mm);	SOT307-2
		body 10 ´ 10 ´ 1.75 mm

1996 Mar 11

2

Philips Semiconductors				Preliminary specification
Satellite sound receiver with I2C-bus control					TDA8745
QUICK REFERENCE DATA
SYMBOL	PARAMETER	CONDITIONS	MIN.	TYP.		MAX.	UNIT
VP1	synthesizer and mixer supply voltage		4.5	5.0		5.5	V
V	I2C-bus supply voltage		4.5	5.0		5.5	V
P2
VP3	general supply voltage		8.0	12.0		13.2	V
IP1	synthesizer and mixer supply current		−	37		48	mA
I	I2C-bus supply current		−	0.6		−	mA
P2
IP3	general supply current		−	35		46	mA
S/N(A)	signal-to-noise ratio secondary channel	A-weighted;	68	77		−	dB
		NR = on; DEEM = 75 μs
Vi(rms)	input sensitivity (RMS value) baseband input	S/N(A) = 40 dB;	−	0.5		1.5	mV
	to mixer	NR = on; DEEM = 75 μs
Vi(rms)	baseband input voltage (RMS value)	THD ≤ 0.5%				200	mV
Vo	output voltage		−8	−6		−4	dBV
Ptot	total power dissipation		−	610		800	mW
Tstg	storage temperature		−65	−		+150	°C
Tamb	operating ambient temperature		−20	−		+70	°C

1996 Mar 11

3

11Mar1996

I 2 C

PDL

12 V

LOUTDEEM

DIAGRAMBLOCK

soundSatellite

SemiconductorsPhilips

5 V

100 μH

4.7 Ω

5 V

PRES DET L

100 μF

22

22

1000 μF

22

nF

nF

nF

2.2

470

1

10

10

1

4.7

10

220 nF

μF

kΩ

μF

μF

μF

μF

nF

nF

SYNGND

VP1

ADDsel

SDA

SCL

I 2 CGND

VP2

Vref

HFGND

AFGND

VP3

CDC L

RECTL

CATT/REC L

CNR D L

CD L

CCL L

EXT L

6

4

12

18

17

14

16

19

10

32

20

41

42

37

38

36

35

34

33

25

Vref

receiver

10

4 MHz

LIMITER

LPF

REDUCTION

INTERFACE

PDR

PDL

PRESENCE

OML

DETECTOR

DC

XTAL

40

CRYSTAL

DE-EMPHASIS

23

O L

HF

PLL

AUDIO

NOISE

OSCILLATOR

flat

50 μs

pF

TUN9 to TUN0

J17

75 μs

with

CHARGE

ϕ

IL2 to IL0

BB

LEV3 to LEV0

NR

DEM1 and DEM0

OS1 and OS0

OM

N

200

12 to

3dB

4 MHz

OML

TDA8745

21

PUMP

I

OMR

2

SLF

2

frequency

12 to

3dB

C

VCO

synthesizer

6.8

33

30 to 40 MHz

HF

AUDIO

NOISE

DE-EMPHASIS

-

PLL

DC

flat

50 μs

22

bus

1 μF

nF

kΩ

LIMITER

LPF

REDUCTION

OR

J17

75 μs

BPFN

2

4

15 pF (1)

PE

control

IR2 to IR0

IR2

PRESENCE

OMR

27 pF

27 pF

3

PRE-BPF

DETECTOR

BASEBAND

IN

IL2

47 μH

1 kΩ

MIXER

27 pF

5

9

11

13

15

7

8

39

1

27

26

28

29

30

31

24

IF OUT

10.7

(2)

IN-1

IN-2

IN-3

IN-4

IN-5

IN-6

470

1

CDC R

RECTR

CATT/REC R

C NR D R

CD R

OUT R

CCL L

EXTR

MBE037

10 nF

10

10

1

4.7

10

220 nF

330 Ω

NARROW

kΩ

μF

μF

μF

μF

nF

nF

DEEM

330 Ω

	10.52 (2)		PRES DET R
330 Ω	NARROW		330
			Ω
	10.7	(2)
330 Ω	WIDE		330
			Ω

When driving more than three filters in parallel, pin 5 should be buffered.		TDA8745	specificationPreliminary
(1)	Add 15 pF for NTSC.
(2)	Ceramic filters:
	SFE10.7MJA10-A (narrow)
	SFE10.52MJA10-A (narrow)
	SFE10.7MS2-A (wide).
	Fig.1 Block diagram (SDIP42).

Philips Semiconductors				Preliminary specification
Satellite sound receiver with I2C-bus control					TDA8745
PINNING
SYMBOL	PIN			DESCRIPTION
	SDIP42		QFP44
CDC R	1		39	DC decoupling capacitor (right channel)
SLF	2		41	synthesizer loop-filter
BASEBAND IN	3		42	baseband input to mixer
VP1	4		43	synthesizer and mixer supply voltage (+5 V)
IF OUT	5		44	intercarrier output from mixer
SYNGND	6		1	synthesizer and mixer ground
IN-5	7		2	intercarrier input 5/port expansion output 1
IN-6	8		3	intercarrier input 6/port expansion output 2
IN-1	9		4	Intercarrier input 1
HFGND	10		5	HF ground
IN-2	11		6	intercarrier input 2
ADD	12		7	I2C-bus address selection
sel
IN-3	13		8	Intercarrier input 3
I2CGND	14		9	I2C-bus ground
IN-4	15		10	intercarrier input 4
V	16		11	I2C-bus supply voltage (+5 V)
P2
SCL	17		12	I2C-bus serial clock input
SDA	18		13	I2C-bus serial data input/output
Vref	19		14	decoupling capacitor for reference voltage
VP3	20		15	general supply voltage (+12 V)
OM	21		17	mono channel output [1¤2(l + r)]
OR	22		18	right channel output
OL	23		19	left channel output
EXTR	24		20	external audio input (right channel)
EXTL	25		21	external audio input (left channel)
CATT/REC R	26		22	attack/recovery capacitor (right channel)
RECTR	27		23	rectifier DC decoupling (right channel)
CNR D R	28		24	noise reduction de-emphasis capacitor (right channel)
CD R	29		25	de-emphasis capacitor (right channel)
DEEM OUT R	30		26	de-emphasis output (right channel)
CCL R	31		27	audio pass-through input (right channel)
AFGND	32		28	AF ground
CCL L	33		29	audio pass-through input (left channel)
DEEM OUT L	34		30	de-emphasis output (left channel)
CD L	35		31	de-emphasis capacitor (left channel)
CNR D L	36		32	noise reduction de-emphasis capacitor (left channel)
RECTL	37		33	rectifier DC decoupling (left channel)
CATT/REC L	38		34	attack/recovery capacitor (left channel)

1996 Mar 11

5

Philips Semiconductors										Preliminary specification
Satellite sound receiver with I2C-bus control										TDA8745
SYMBOL	PIN									DESCRIPTION
	SDIP42		QFP44
PRES DET R	39		35		presence detector timing (right channel)
XTAL	40		36		crystal input for 4 MHz oscillator
PRES DET L	41		37		presence detector timing (left channel)
CDC L	42		38		DC decoupling capacitor (left channel)
n.c.	−		16		not connected
n.c.	−		40		not connected
		handbook, halfpage								CDC L
				CDC R		1		42
					SLF	2		41		PRES DET L
			BASEBAND IN			3		40		XTAL
					V P1
						4		39		PRES DET R
										CATT/REC L
				IF OUT		5		38
										RECT L
				SYNGND		6		37
										C NR D L
					IN-5	7		36
										C D L
					IN-6	8		35
					IN-1	9		34		DEEM OUT L
										C CL L
				HFGND		10		33
					IN-2	11	TDA8745	32		AFGND
				ADD sel						C CL R
						12		31
					IN-3	13		30		DEEM OUT R
				I 2 CGND						C D R
						14		29
										C NR D R
					IN-4	15		28
					V P2					RECTR
						16		27
										CATT/REC R
					SCL	17		26
					SDA	18		25		EXT L
					Vref	19		24		EXT R
					V P3
						20		23		O L
					OM
						21		22		O R
							MBE035

Fig.2 Pin configuration (SDIP42).

1996 Mar 11

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Philips Semiconductors	Preliminary specification
Satellite sound receiver with I2C-bus control	TDA8745

handbook, full pagewidth

	OUTIF	V	BASEBANDIN	SLF	n.c.	C	C	PRESDET L	XTAL	PRESDET R	C
		P1				DCR	DC L				ATT/RECL
	44	43	42	41	40	39	38	37	36	35	34
SYNGND	1										33	RECTL
IN-5	2										32	CNR D L
IN-6	3										31	CD L
IN-1	4										30	DEEM OUT L
HFGND	5										29	CCL L
IN-2	6				TDA8745H						28	AFGND
ADDsel	7										27	CCL R
IN-3	8										26	DEEM OUT R
I2 CGND	9										25	C D R
IN-4	10										24	C NR D R
VP2	11										23	RECTR
	12	13	14	15	16	17	18	19	20	21	22	MBE034
	SCL	SDA	V	V	n.c.	O	O	O	EXT	EXT	RATT/REC
			ref	P3		M	R	L	R	L
											C

Fig.3 Pin configuration (QFP44).

1996 Mar 11

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Philips Semiconductors	Preliminary specification
Satellite sound receiver with I2C-bus control	TDA8745

FUNCTIONAL DESCRIPTION

Satellite sound

The baseband signal coming from a satellite tuner comprises the demodulated video signal plus a number of sound carriers in the event of reception of a PAL, NTSC or SECAM satellite signal.

Nearest to the video signal is the main sound carrier which carries the mono 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. These can be used for stereo or multi-language sound related to the video signal, or for unrelated radio sound. These carriers are also FM modulated, and 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.

For accurate tuning to the many sound carriers, an internal frequency synthesizer and mixer are used to transfer the sound carriers to intermediate frequencies of

10.7 and 10.52 MHz.

The TDA8745 contains all circuitry for the processing of the main channel and secondary channels, from baseband signal to line (SCART) output drivers. By means of external band-pass filters the desired frequencies coming from the synthesizer/mixer are routed to the IF limiter/demodulator inputs.

Band-pass filter and mixer

Before the incoming baseband signal is applied to the mixer, the signal is filtered. Related to the sound carriers, the level of the video part of the baseband signal can be much higher, so to avoid overload it is desirable to attenuate the latter, this is also to avoid interference (additional unwanted mix of signals after mixing).

The internal band-pass filter (pass band from approximately 4 to 10 MHz) is completed by a simple external notch filter. The external filter provides substantial attenuation of the video colour carrier. The notch filter is chosen to be external because the required notch frequency is TV standard dependent and also because an accurate on-chip notch filter requires a tuning mechanism (consuming additional chip area).

The mixer is a double-balanced mixer with degeneration, this to accommodate the level of the filter output signal.

The mixer transfers the different sound carrier frequencies to fixed intermediate frequencies of 10.7 and 10.52 MHz. These frequencies are fed via an internal buffer stage to external ceramic band-pass filters before they are routed to the two demodulator inputs. The buffer stage can drive up to three external ceramic band-pass filters (assuming 330 Ω filter terminations) but this can be increased to four or more by adding an external buffer.

Synthesizer

The synthesizer consists of the following parts:

∙Reference oscillator

∙Reference divider

∙A 10-bit programmable divider

∙Phase detector

∙Charge pump

∙Voltage Controlled Oscillator (VCO)

∙Divide-by-two circuit.

The reference frequency circuit consists of a 4 MHz crystal oscillator and a divider (by 200). The resulting reference frequency of 20 kHz is fed to the phase detector.

The programmable divider consists of a series of cells (divide by 2 or 3) connected as a ripple counter.

The minimum division ratio is 2n and the maximum division ratio is 2n + 1 − 1.

The programmable divider output signal is also fed to the phase detector. The charge pump provides output current pulses in accordance with the signals from the phase detector. The final tuning voltage for the VCO is provided by the loop filter and a buffer amplifier.

The oscillator frequency range is from

29.04 to 40.94 MHz, depending on the setting of the programmable divider (by the TUN signal). The tuning voltage is clipped to limit the VCO frequency range.

The frequency of the oscillator is divided-by-two before it is applied to the mixer (to obtain the desired 10 kHz resolution).

Left and right channel inputs

A maximum of six inputs are available (pins 9, 11, 13, 15, 7 and 8). External ceramic band-pass filters, which are tuned to the desired intermediate frequencies, route the signals to the inputs.

For stereo purposes the TDA8745 contains two identical secondary sound processing channels (secondary channel 1 will also be referred to as ‘left’ or ‘language 1’ and secondary channel 2 as ‘right’ or ‘language 2’).

1996 Mar 11

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Philips Semiconductors	Preliminary specification
Satellite sound receiver with I2C-bus control	TDA8745

With the input selection every input pin of the left and/or right channel can be independently selected. Input selection for the left channel is controlled by the IL signal and for the right channel by the IR signal.

From the inputs, the signals are coupled to the limiter/amplifier and to the PLL demodulator of each channel. The output signal from the PLL is routed to both the presence detector and audio level control.

The inputs of pins 7 and 8 can be changed into digital outputs for external switching purposes, set by the so called Port Extension bit (PE). Not used inputs should be connected to ground. Note that the inputs of pins 7 and 8 are also floating when not in Port Extension mode.

Presence detector

The presence detector is used to determine if a carrier is present on the channel of interest. It does so by measuring the amount of high frequency noise (>20 kHz) in the audio signal, which is directly related to the C/N (carrier-to-noise ratio) at the IF input. If a carrier is present, these high frequencies are fairly moderate, if no carrier is present, strong noise components are present.

The audio signal, first high-pass filtered and then rectified, is filtered by the components at pins 41 and 39

(PRES DET L and PRES DET R). The DC level at this pin is then compared with an internal reference voltage. If the level at pins 41 and 39 exceeds this voltage level, the presence detector output goes HIGH (no carrier).

This output signal can be used to drive the output mute (if bit PDM = 1; see Section “Output selection”) and can be monitored by reading bits PDL and PDR. The detection level can be modified by changing the leakage resistor at pins 41 and 39, a higher resistor value gives a ‘no carrier’ response ant C/N levels detected as ‘carrier present’ with a lower resistor value.

Audio level control

Each demodulator output signal is amplified in a buffer amplifier and DC decoupled by means of electrolytic capacitors connected to pin 42 (left) and pin 1 (right).

The output level of all channels is -6 dBV typical at a frequency deviation of the FM signal of 54% of the maximum deviation (i.e 0.54 ´ 85 kHz = 46 kHz for the main channel and 0.54 ´ 50 kHz = 27 kHz for the secondary channels) at 1 kHz modulation frequency (reference level).

To adjust for different (main channel) modulation depths used at some satellites the audio level is made adjustable, the signal can be controlled in steps of 1 dB from

-12 dB to +3 dB by the LEV signal.

Noise Reduction (NR)

To improve the quality of the secondary channels, the audio signal is processed at the transmitter side before modulation. For an overall flat audio response the inverse processing must take place after demodulation. This is achieved in the NR.

The NR can be regarded as an input level dependent Low-Pass Filter (LPF) [adaptive de-emphasis system] followed by a fixed de-emphasis. Figure 3 shows the transfer characteristics as function of the input level (normalized to input level, and without the fixed de-emphasis).

At maximum input level (50 kHz frequency deviation, referred to as 0 dB) the frequency response of the first part (i.e. without fixed de-emphasis) is nearly flat (note the small dip around 3 kHz in Fig.3; this is a system attribute). As the input level is X dB lowered, the higher output frequencies will be reduced an extra X dB with respect to the lower frequencies (1 : 2 expansion).

If a main carrier signal is received, the NR can be bypassed at which the signal is fed directly to the de-emphasis circuit. The noise reduction is active when the NR signal (via I2C-bus) is logic 1.

De-emphasis

De-emphasis is realized by means of several internal resistors and an external capacitor to ground. Via the I2C-bus, the DEM signal can be switched between 50 ms, 75 ms, J17 and no de-emphasis. Figure 4 shows these four different possibilities.

Output selection

With the output selector the output pins 23 and 22 can be switched to the left and right satellite channels

(pins 33 and 31) or to the external inputs (pins 25 and 24) for an other signal source or for connection of a decoder box. the OS1 and OS0 bits determine this selection.

Pin 21 is a separate output which delivers the mono channel. The mono signal is the sum of pin 23 (left) and pin 22 (right) output signal [1¤2(l + r)].

1996 Mar 11

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Philips Semiconductors	Preliminary specification
Satellite sound receiver with I2C-bus control	TDA8745

Output pins 23 and 22 can be muted by setting the OML and OMR signals to logic 1. In addition, automatic muting is also possible, the presence detector (as

described in Section “Presence detector”) sets the PDL bit (PDR for other channel). Absence of a carrier at the selected frequency results in automatic muting. This mechanism is enabled or inhibited by the PDM bit (Presence Detector auto Mute).

All outputs (pins 21, 22 and 23) are line drivers with SCART level capability and are short-circuit protected by means of 125 Ω output resistors. Pins 34 and 30 are also line drivers at SCART level and can be used as signal outputs before the IC’s output selection (i.e. for decoder box use).

ABBREVIATIONS

BPF = Band-Pass Filter.

fmod = modulating frequency.

fM = frequency deviation of the main Channel.

fS1 = frequency deviation of secondary Channel 1 (left).

fS2 = frequency deviation of secondary Channel 2 (right).

fOM = carrier frequency of main Channel.

fOS1 = carrier frequency of secondary Channel 1. fOS2 = carrier frequency of secondary Channel 2. IF = Intermediate Frequency.

IL = Input Left.

IR = Input Right.

LPF = Low-Pass Filter.

NR = Noise Reduction.

OML = Output Mute Left.

OMR = Output Mute Right.

OS = Output Select.

PDM = Presence Detector auto Mute. PE = Port Extension.

PLL = Phase-Locked Loop.

POR = Power-On Reset.

S/N = Signal-to-Noise ratio.

VCO = Voltage Controlled Oscillator.

0																																MBE284									8																																				MBE285
handbook, halfpage																														0 dB											handbook, halfpage
transfer																																									transfer
(dB)																																									(dB)
				4																																					4
				8																																					0																																	flat
																																													4
			12
			16																																										8																		J17										50 μs
			20																												20 dB													12
																																												16
			24																																																																	75 μs
							102							103																4							105											102							103																			4						105
10																						10									f	(Hz)									10																									10										(Hz)
																																																																										f

Fig.4 Noise reduction transfer as function of
input level.	Fig.5 LF de-emphasis curves.

1996 Mar 11

10

Philips Semiconductors							Preliminary specification
Satellite sound receiver with I2C-bus control								TDA8745
I2C-BUS PROTOCOL
Table 1 Slave receiver/transmitter address: D4 or D6 (HEX)
BIT 7	BIT 6	BIT 5	BIT 4		BIT 3	BIT 2	BIT 1		BIT 0
1	1	0	1		0	1	AS(1)				(2)
									R/W

Notes

1.AS bit defined by level at address select (pin 12); 0 V = logic 0; 5 V = logic 1.

2.R/W = 0; TDA8745 is receiver (microcontroller is master transmitter). R/W = 1; TDA8745 is transmitter (microcontroller is master receiver).

TDA8745 receiver use

In the receiver mode the device has four subaddresses with auto-increment, as shown in Tables 2 to 5.

Table 2 Input byte SA: 00; situation after POR

IL2		IL1	IL0		IR2	IR1	IR0	TUN9	TUN8
i7		i6	i5		i4	i3	i2	i1	i0
0		0	0		0	0	1	1	0
Table 3 Tuning byte SA: 01; situation after POR
TUN7		TUN6	TUN5		TUN4	TUN3	TUN2	TUN1	TUN0
t7		t6	t5		t4	t3	t2	t1	t0
1		1	1		0	1	1	0	0
Table 4 Select byte SA: 02; situation after POR
TEST		BB	OS1		OS0	PDM	PE	OML	OMR
s7		s6	s5		s4	s3	s2	s1	s0
0		0	0		0	0	0	1	1
Table 5 Audio byte SA: 03; situation after POR
LEV3		LEV2	LEV1		LEV0	NR	DEM1	DEM0	BPFN
a7		a6	a5		a4	a3	a2	a1	a0
1		1	0		0	1	1	1	0
TDA8745 transmitter use
No subaddress.
Table 6 Read byte
PDL		PDR	−		−	−	−	−	POR
r7		r6	r5		r4	r3	r2	r1	r0
0 or 1		0 or 1	1		1	1	1	1	0 or 1

1996 Mar 11

11

Philips Semiconductors	Preliminary specification
Satellite sound receiver with I2C-bus control	TDA8745

Slave receiver mode (bits transmitted from microcontroller to TDA8745)

Different IF inputs can be selected for the PLLs, for switching between different external BPFs and/or channels; see Tables 7 and 8.

Table 7 IL2 to IL0; Input Left; note 1

	IL2	IL1	IL0	PE(2)	MODE
	i7	i6	i5	s2
	0	0	0	0	IF input IN-1 selected for left PLL (after POR)
	0	0	1	0	IF input IN-2 selected for left PLL
	0	1	0	0	IF input IN-3 selected for left PLL
	0	1	1	0	IF input IN-4 selected for left PLL
	1	0	0	0	IF input IN-5 selected for left PLL
	1	0	1	0	IF input IN-6 selected for left PLL
	1	1	0	0	no selection
	1	1	1	0	no selection
	X	0	0	1	IF input IN-1 selected for left PLL
	X	0	1	1	IF input IN-2 selected for left PLL
	X	1	0	1	IF input IN-3 selected for left PLL
	X	1	1	1	IF input IN-4 selected for left PLL
	0	X	X	1	IF input IN-5 used as output; 0 = 0 V
	1	X	X	1	IF input IN-5 used as output; 1 = 5 V

Notes

1.X = don’t care.

2.Bit PE (s2) can be set to logic 1 to change IF input 5 into digital output for external switching purposes.

1996 Mar 11

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