TDA9812 datasheet(18/32 Pages) PHILIPS

18 / 32 page

1995 Mar 21

Philips Semiconductors

Preliminary speciﬁcation

Multistandard VIF-PLL and

FM-PLL/AM demodulator

TDA9812

12. The intermodulation figures are defined:

α1.1 = 20 log (V0 at 4.4 MHz/V0 at 1.1 MHz) + 3.6 dB; α1.1 value at 1.1 MHz

referenced to black/white signal;

α3.3 = 20 log (V0 at 4.4 MHz/V0 at 3.3 MHz); α3.3 value at 3.3 MHz referenced to

colour carrier.

13. Response speed valid for a VIF input level range of 200

µVupto70mV.

14. To match the AFC output signal to different tuning systems a current source output is provided. The test circuit is

given in Fig.12. The AFC-steepness can be changed by the resistors at pin 23.

15. Depending on the ratio

∆C/C0 of the LC resonant circuit of VCO (Q > 50; see note 3; C0 =Cint +Cext).

16. Source impedance: 2.3 k

Ω in parallel to 12 pF (SAW filter); fIF = 38.9 MHz.

17. The intercarrier output signal at pin 20 can be calculated by the following formula taking into account the video output

signal at pin 21 (Vo video(p-p) = 1 V typical) as a reference:

with

= correction term for RMS value,

= sound-to-picture carrier ratio at VIF input (pins 1 and 2) in dB,

6 dB = correction term of internal circuitry

and

±3 dB = tolerance of video output and intercarrier output amplitude V

o(rms).

Example: SAW filter G1962 (sound shelf: 20 dB)

⇒⇒ V

o(rms) = 32 mV typical.

18. Input level for second IF from an external generator with 50

Ω source impedance. AC-coupled with 10 nF capacitor,

fmod = 1 kHz, 27 kHz (54% FM deviation) of audio references. A VIF/SIF input signal is not permitted. Pins 8 and 28

have to be connected to positive supply voltage for minimum IF gain. S/N and THD measurements are taken at 50

µs

de-emphasis.

Second IF input level 10 mV RMS.

19. Measured with an FM deviation of 27 kHz the typical AF output signal is 500 mV RMS (Rx =0 Ω; see Fig.17). By

using Rx = 470 Ω the AF output signal is attenuated by 6 dB (250 mV RMS). For handling an FM deviation of more

than 53 kHz the AF output signal has to be reduced by using Rx in order to avoid clipping (THD < 1.5%). For an FM

deviation up to 100 kHz an attenuation of 6 dB is recommended with Rx = 470 Ω.

20. The leakage current of the decoupling capacitor (2.2

µF) should not exceed 1 µA.

21. For all S/N measurements the used vision IF modulator has to meet the following specifications:

Incidental phase modulation for black-to-white jump less than 0.5 degrees.

Picture-to-sound carrier ratio; PC/SC = 13 dB; (transmitter).

Sound shelf of VIF SAW filter: minimum 20 dB.

22. Measurements taken with SAW filter K6256 (Siemens) for vision and sound IF (sound shelf: 20 dB). Input level

Vi SIF = 10 mV RMS, 27 kHz (54% FM deviation).

23. The PC/SC ratio at pins 1 and 2 is calculated as the addition of TV transmitter PC/SC ratio and SAW filter PC/SC

ratio. This PC/SC ratio is necessary to achieve the S/N(W) values as noted. A different PC/SC ratio will change these

values.

24. Measurements taken with SAW filter L9453 (Siemens) for AM sound IF (suppressed picture carrier).

25. The input voltage has to be V > 2.8 V, or open-circuit.

o rms

()

–

()

-----------

iSC

iPC

------------

() 6dB 3 dB

---------------------------------------------------------------

-----------

iSC

iPC

------------

()

iSC

iPC

------------

27 dB

–

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