TDA4504B Datasheet, PDF (17/26 Pages) NXP Semiconductors – Small signal combination for multistandard colour TV

Philips Semiconductors
Small signal combination for multistandard colour TV
Product specification
TDA4504B
Notes to the characteristics
1. Supplying a current of 9 mA to pin 12 starts the horizontal oscillator. This current can be obtained via a bleed circuit
from the mains rectifier whilst the main supply for the device (V_P) is obtained from the horizontal output stage. The
load current of the driver must be added to the value given above.
2. On set AGC.
3. The input impedance has been chosen such that a SAW filter can be employed.
4. Measured with 0 dB = 450 µV.
5. Measured at 10 mV (RMS) 100% input signal.
6. Projected zero point; i.e. with switched demodulator.
7. The output signal amplitude is determined by the AGC detector. For negative modulation the sync tip level is used
as reference. With positive modulation the white level is stabilized
8. Measured according to the test line given in Fig.3.
a) The differential gain is expressed as a percentage of the difference in peak amplitudes between the largest and
smallest value relative to the subcarrier amplitude at blanking level.
b) The differential phase is defined as the difference in degrees between the largest and smallest phase angle.
c) The differential gain and phase are measured with a DSB signal.
9. This figure is valid for the complete video signal amplitude (peak white to black). The non-linearity is expressed as a
percentage of the maximum deviation of a luminance step from the mean step, with respect to the mean step.
10. The test set-up and input conditions are given in Fig.5. The figures are measured at an input signal of 10 mV (RMS).
11. Measure with a source impedance of 75 Ω. The signal-to-noise ratio =
20 log -V----_n---₍^V--_R--^o--_M---b-_S--l-₎-a---ca---k-t----B-t--o---=---w---5-h----iM-t-e---H----z--
12. These figures are based on sample tests.
13. By means of the system switch, two conditions can be obtained. Negative modulation with sync tip level AGC. This
is obtained with pin 32 connected to ground. Positive modulation with peak white AGC. This is obtained with pin 32
connected to the positive supply.
14. When the video switch is in the external mode the first control loop in the synchronization circuit is not switched to a
long time constant when weak signals are received.
15. Defined as ( 20 log ) --V--V--^o---_o--u--w-n----wa---n-a--t-n-e--t-d-e---d-v---i-vd---i-e-d--o-e----o-b----lb-a---lc-a--k-c----k-t--o---t---o-w-----wh----ih-t--e-i-t--e-- ; measured at 4.4 MHz.
16. The indicated figures are measured at an input signal of 10 mV RMS. The unloaded Q-factor of the reference tuned
circuit is 70.
With very weak input signals the drive signal for the AFC circuit will have a high noise content. This noise input has
a asymmetrical frequency spectrum which will cause an offset of the AFC output voltage. To avoid problems due to
this effect a notch filter can be built into the demodulator tuned circuit. The characteristics given for weak signals are
measured without a notch circuit, with a SAW filter connected in front of the IC input signal such that the input signal
of the IC is 150 µV (RMS value).
17. The minimum value is obtained by connecting a 1.8 kΩ resistor between pins 15 and 28. The slicing level can be
varied by changing the value of this resistor (higher resistor value results in larger value of the minimum sync pulse
amplitude). The slicing level is independent of the video information.
18. Frequency control is obtained by supplying a correction current to the oscillator RC network via a resistor connected
between the phase 1 detector output and the oscillator network. The oscillator can be adjusted to the correct
frequency by short circuiting the sync separator bias network (pin 28) to +V_P. To avoid the need of a VCR switch the
time constant of the phase detector at strong input signals is sufficiently short to get a stable picture during VCR
playback. During the vertical retrace period the time constant is even shorter so that the head-errors of the VCR are
February 1992
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