TDA3845 Datasheet, PDF (9/18 Pages) NXP Semiconductors – Quasi split-sound circuit and AM demodulator

Philips Semiconductors
Quasi split-sound circuit and AM
demodulator
Objective specification
TDA3845; TDA3845T
8. For all S/N measurements the used vision IF modulator must conform to the following:
Incidental phase modulation for black-to-white jump should be less than 0.5 degrees. Intercarrier performance,
measured with the television demodulator AMF2 (intercarrier mode weighted S/N ratio) better than 60 dB for 6 kHz
sinewave black-to-white video modulation. Weighted S/N ratio of the demodulated intercarrier signals in accordance
with CCIR 468-3, measured with de-emphasis of 50 µs.
The indicated (S + W)/W ratio X/Y concerns the sound channels 1 and 2 that means demodulated intercarrier signals
of 5.5 and 5.74 MHz respectively.
9. Sound carrier frequency in the range of 30 to 40 MHz modulated with f = 1 kHz and a modulation depth of 80%.
IF input signal (sound carrier) V_1-16 = 10 mV (RMS).
10. The capacitor at pin 4 can be omitted, however, the (S + W)/W figure for the AM sound (standard L) will be up to
8 dB worse in the IF voltage range 1 mV to 100 mV.
11. When the supply at V_P2 = 12 V the performance will be comparable with the performance when V_P1 = 5 to 8 V.
The power supply pin that is not in use should be disconnected.
12. The maximum value given as minimum 120 kHz and typical 700 kHz.
13. Voltage ripple < 200 mV (p-p) at 70 Hz.
January 1993
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