Philips TDA4504B Datasheet

INTEGRATED CIRCUITS

DATA SH EET

TDA4504B

Small signal combination for multistandard colour TV

Product speciﬁcation File under Integrated Circuits, IC02

February 1992

Philips Semiconductors Product speciﬁcation

Small signal combination for multistandard colour TV TDA4504B

FEATURES

• Gain controlled vision IF amplifier

• Synchronous demodulator for negative and positive

demodulation

• AGC detector operating on peak sync amplitude for negative demodulation and on peak white level for positive demodulation

• Tuner AGC

• AFC circuit with two control polarities and on/off-switch

• Video preamplifier

• Video switch to select either the internal video signal or

an external video signal

• Horizontal oscillator and synchronization circuit with two control loops

• Vertical synchronization (divider system), ramp generator and driver with automatic amplitude adjustment for 50 and 60 Hz

• Transmitter identification (mute)

• Sandcastle pulse generation

• VCR/auto VCR switch

• Start-up circuit

• Vertical guard

GENERAL DESCRIPTION

Having the capability to demodulate IF signals with either positive or negative-going video information, the TDA4504B (Fig.1) is contained within a 32 pin encapsulation. It includes a three-stage vision IF amplifier, mute circuit, AFC and AGC circuitry, fully synchronised horizontal and vertical timebases with drive circuits and integral three-level sandcastle pulse generator. A functional colour tv receiver can thus be realized with the addition of a tuner, audio demodulator and amplifier, chroma decoder and respective line and field deflection circuitry.

ORDERING INFORMATION

EXTENDED

TYPE NUMBER

TDA4504B 32 DIL plastic SOT201

Note

1. SOT201-1; 1996 November 29

PINS PIN POSITION MATERIAL CODE

PACKAGE

(1)

February 1992 2

Philips Semiconductors Product speciﬁcation

Small signal combination for multistandard colour TV

TDA4504B

February 1992 3

Fig.1 Block diagram.

Philips Semiconductors Product speciﬁcation

Small signal combination for multistandard colour TV TDA4504B

QUICK REFERENCE DATA

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Supply

Video

9-10

S/N signal to noise ratio V

Video switch

(p-p)

13(p-p)

15(p-p)

Sync

5(p-p)

positive supply voltage pin 8 10 12 13.2 V supply current pin 8 90 115 140 mA start current pin 12 − 6.5 9 mA

IF sensitivity (RMS value) 25 40 65 µV IF gain control range − 74 − dB

input signal =

− 58 − dB

10 mV AFC output voltage swing 10.5 − 11.5 V video output amplitude − 2 − V

internal video input − 2 − V external video input − 1 − V video output − 2.5 − V

sync pulse input amplitude (p-p) 200 −−mV ﬂyback input current 0.1 − 2mA sandcastle output during burst key 8 −−V

- during hor. blanking 4 4.4 5 V

- during vert. blanking 2.1 3.3 3.7 V

video transmitter identiﬁcation

- no signal condition − 0.3 − V

- 50 Hz signal − 12 − V

- 60 Hz signal − 9 − V

vert. feedback

- DC voltage 2.9 3.3 3.7 V

- AC voltage − 1 − V

February 1992 4

Philips Semiconductors Product speciﬁcation

Small signal combination for multistandard colour TV TDA4504B

PINNING

PIN DESCRIPTION

1 black level internal video 2 AGC take over (output) 3 vertical ramp generator (output) 4 vertical drive (output) 5 vertical feedback (input) 6 tuner AGC (input) 7 ground 8 supply voltage 9 vision IF (input) 10 vision IF (input) 11 IF AGC (output) 12 start horizontal oscillator (output)/AFC polarity switch (input) 13 external video (input) 14 mute/50 / 60 Hz (output) 15 video switch (output) 16 internal video (input) 17 VCR switch (input) 18 video switch (input) 19 ground for some critical parts 20 video ampliﬁer (output) 21 AFC (output) 22 AFC S/H, AFC switch (input) 23 vision demodulator tuned circuit 24 vision demodulator tuned circuit 25 coincidence detector/transmitter identiﬁcation 26 horizontal oscillator 27 phase 1 detector (output) 28 sync separator (input) 29 horizontal drive (output) 30 sandcastle output/horizontal ﬂyback (input) 31 phase 2 detector (output) 32 AGC system switch (input)

February 1992 5

Philips Semiconductors Product speciﬁcation

Small signal combination for multistandard colour TV TDA4504B

FUNCTIONAL DESCRIPTION Vision IF ampliﬁer, demodulator

and video ampliﬁer

Each of the three AC-coupled IF stages permit the omission of DC feedback and possess a control range in excess of 20 dB.

The IF amplifier, which is completely symmetrical, is followed by a passive synchronous demodulator providing a regenerated carrier signal. This is limited by a logarithmic limiter circuit prior to its application to the demodulator.

A noise clamp circuit is provided at the video input (pin 16) to limit interference pulses below the sync tip level and is more efficient than a noise inverter in providing improved picture stability during the presence of interference.

The video amplifier has good linearity and bandwidth figures.

AFC-circuit

Obtaining the AFC reference signal from the demodulator tuned circuit presents the advantage of utilizing a single tuned circuit and one adjustment. However, since the frequency spectrum of the signal applied to the demodulator is determined by the characteristic of the SAW filter, the resultant asymmetrical spectrum with respect to the vision carrier causes the AFC output voltage to be dependent upon the video signal. The TDA4504B thus contains a sample-and-hold circuit.

With negative-going vision signals the AFC is active only during the sync pulse period. When positive-going signals are applied to the device, however, the AFC is continuously active but filtered to ensure only a small by-pass current is present in the sample-and-hold circuit.

With weak input signals the drive signal will contain considerable noise which also possesses an asymmetrical frequency spectrum and could create an offset in the AFC output voltage. The inclusion of a notch in the demodulator tuned circuit minimises this effect.

The sample-and-hold circuit is followed by a high impedance output amplifier. Thus the AFC control gradient depends upon the load impedance.

The AFC polarity switch is combined with the start circuit (pin 12). It has a negative slope when pin 12 is open or connected to the main supply and a positive slope when pin 12 is grounded. The AFC is disabled when the sample connection (pin 22) is grounded.

February 1992 6

Philips Semiconductors Product speciﬁcation

Small signal combination for multistandard colour TV TDA4504B

AGC circuit

For signals employing negative modulation the AGC detector operates on peak sync level but upon peak white content with those having positive modulation. Selection is facilitated by the system switch (pin 32):

pin 32 HIGH/open: positive modulation pin 32 LOW: negative modulation

The AGC detector currents are:

positive modulation negative modulation charge 1 µA55µA discharge 3 mA 1.5 mA

With a 6.8 µF AGC capacitor, the video tilt will be < 10% for positively modulated signals and < 2% for negative modulation.

To obtain a rapid AGC action when executing a search tuning operation with the circuit set for peak white AGC, the charge current is held at 55 µA until the detection of a transmitted signal.

The transmitter identiﬁcation

A mute signal is generated to disable the audio preamplifier of an audio demodulator during the absence of a transmission signal. When the video switch is in the internal mode, the identification of a transmitted signal is derived from the coincidence detector. In the external mode the IF part of the circuit has its own identification system. The system relies upon the detection of sync. pulses on the incoming IF signal. The separated horizontal sync pulse charges the capacitor on pin 25 which drives the mute output (pin 14).

The connection of a 1 MΩ resistor between pin 25 and V 50/60 Hz information derived from the internal vertical divider section (see 50/60 Hz truth table).

MUTE Truth Table:

Input signal Pins 9 and 10

pin 25 9.5 V 9.5 V 0.3 V 9.5 V 9.5 V 9.5 V 0.3 V pin 28 50 Hz 60 Hz none 50 Hz 60 Hz none 50/60 Hz pin 18 LOW LOW LOW/

pin 14 12 V 9 V 0.3 V 12 V 9 V 12 V 0.3 V

50 Hz 60 Hz none 50/60 Hz 50/60 Hz 50/60 Hz none

HIGH

results in the mute information being overruled by the

HIGH HIGH HIGH HIGH

February 1992 7

Philips Semiconductors Product speciﬁcation

Small signal combination for multistandard colour TV TDA4504B

50/60 Hz Information

In the external video mode and with a resistor of 1 MΩ from pin 25 to VCC the mute is overruled by the 50/60 Hz information from the divider system.

50/60 Hz Truth Table:

Input Signal

Pin 9/10

Pin 25 9.5 9.5 0.3 9.5 9.5 9.5

Pin 28 50 Hz 60 Hz None 50 Hz 60 Hz None

Pin 18 LOW LOW LOW HIGH HIGH HIGH Pin 14 12 9 0.3 12 9 12

VCR switch

Flywheel horizontal synchronization is desirable when receiving weak signals marred by noise but is usually unnecessary when receiving stronger off-air signals unless certain types of interference or multipath reception are apparent. Due to the inherent instability of VCR signals, however, the horizontal time constant should be shorter to prevent loss of horizontal synchronization in the early part of the scan. Provision is therefore incorporated to automatically switch the short time constant such that a strong signal instigates the 'VCR' mode and a weak signal triggers the 'TV' mode. The connection of a switch to pin 17 provides for this to be accomplished manually and may take the form of an auxiliary switching function associated with a designated program selector button.

The TDA4504B has a separate pin (pin 17) for the VCR switch:

pin 17 HIGH: VCR mode fast time constant; ungated pin 17 n.c.: auto VCR mode pin 17 LOW: TV mode slow time constant; gated

Video-switch

50 Hz 60 Hz None Don’t care Don’t care Don’t care

Video output from the demodulator is filtered to remove the audio carrier and DC-coupled to pin 16. If AC-coupling is employed the internal noise clamp will operate on sync. tips.

The TDA4504B provides the opportunity for a direct video connection (e.g. via a peritel connector) to be made to the device at pin 13. Selection between internal and external video is made by applying a switching potential to pin 18.

Video switch:

pin 18 LOW: internal video pin 18 HIGH: external video

Gain reduction

To prevent crosstalk between the IF stages and the horizontal oscillator when the device is operated in its external video mode with no RF input, the TDA4504B incorporates an option to reduce IF gain by 20 dB. This is accomplished by connecting a 39 kΩ resistor between pin 17 and ground. Omission of this component results in the IF amplifier remaining at full gain.

In the internal video mode the resistor must be disconnected to achieve the auto-VCR mode.

February 1992 8

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