Philips TDA3867T Datasheet

INTEGRATED CIRCUITS

DATA SH EET

TDA3867T

Quasi-split sound processor with two FM demodulators

Preliminary speciﬁcation File under Integrated Circuits, IC02

January 1992

Philips Semiconductors Preliminary speciﬁcation

Quasi-split sound processor with two FM demodulators TDA3867T

FEATURES

• Quasi-split sound processor for all FM standards e.g. B/G

• Reduction of spurious video signals by tracking function and AFC for the vision carrier reference circuit; (indispensable

for NICAM)

• AF2 signal automatically muted (at B/G) by the input signal level

GENERAL DESCRIPTION

Symmetrical IF input and gain controlled wideband IF amplifier. AGC generation due to peak sync Reference amplifier for the regeneration of the vision carrier. Optimized limiting amplifier for AM suppression in the regenerated vision carrier signal and 90° phase shifter. Intercarrier mixer for FM sound, output with low-pass filter. Separate signal processing for 5.5 and 5.74 MHz intercarriers. Wide supply voltage range, only 300 mW power dissipation at 5 V.

QUICK REFERENCE DATA

SYMBOL PARAMETER MIN. TYP. MAX. UNIT

i IF

supply voltage (pin 24) 4.5 5 8.8 V supply current (pin 24) − 60 72 mA IF input sensitivity (−3 dB) − 70 100 µV

audio output signal (RMS value) − 1 − V THD total harmonic distortion − 0.5 − % S/N (W) weighted signal-to-noise ratio

for FM − 68 − dB for FM with 6 kHz sinus vision modulation − 56 − dB

ORDERING AND PACKAGE INFORMATION

EXTENDED

TYPE NUMBER

PINS PIN POSITION MATERIAL CODE

TDA3867T 28 mini-pack plastic SOT136A

PACKAGE

(1)

Note

1. SOT136-1; 1997 January 8.

January 1992 2

Philips Semiconductors Preliminary speciﬁcation

Quasi-split sound processor with two FM demodulators TDA3867T

Fig.1 Block diagram.

January 1992 3

Philips Semiconductors Preliminary speciﬁcation

Quasi-split sound processor with two FM demodulators TDA3867T

PINNING

SYMBOL PIN DESCRIPTION

n.c. 1 not connected n.c. 2 not connected C

AGC

3 charge capacitor for AGC n.c. 4 not connected n.c. 5 not connected MATR 6 input for stereo matrix correction FM2R1 7 reference circuit for FM2 (5.74 MHz) FM2R2 8 reference circuit for FM2 (5,74 MHz) AF2 9 AF2 output (AF out of 5.74 MHz) AF1 10 AF1 output (AF out of 5.5 MHz) FM1R1 11 reference circuit for FM1 (5.5 MHz) FM1R2 12 reference circuit for FM1 (5.5 MHz) n.c. 13 not connected VC-R1 14 reference circuit for the vision carrier (38.9 MHz) VC-R2 15 reference circuit for the vision carrier (38.9 MHz) TRACK 16 DC output level for tracking n.c. 17 not connected FM1I 18 intercarrier input for FM1 (5.5 MHz) C

AF1

19 DC-decoupling capacitor for FM1 demodulator (AF1) ICO 20 intercarrier output signal (5.5/5.74 MHz) C

AF2

21 DC-decoupling capacitor for FM2 demodulator (AF2) FM2I 22 intercarrier input for FM2 (5.74 MHz) GND 23 ground (0 V) V

24 +5 to +8 V supply voltage n.c. 25 not connected n.c. 26 not connected FMIF1 27 IF difference input 1 (B/G standard, 38.9 MHz) FMIF2 28 IF difference input 2 (B/G standard, 38.9 MHz)

PIN CONFIGURATION

Fig.2 Pin configuration.

January 1992 4

Philips Semiconductors Preliminary speciﬁcation

Quasi-split sound processor with two FM demodulators TDA3867T

FUNCTIONAL DESCRIPTION

The quasi-split sound processor is suitable for all FM standards (e. g. B/G). The AGC detector uses peak sync level. Sound carrier SC1 (5.5 MHz) provides AF1, sound carrier SC2 (5.74 MHz) provides AF2. With no sound carrier SC2 on pin 22, AF2 output is muted. The mute circuit prevents false signal recognition in the stereo decoder at high IF signal levels when no second sound carrier exists (mono) and an AF signal is present in the identification signal frequency range. With 1 mV on pin 22, under measurement conditions, AF2 is switched on (see limiting amplifier). Weak input signals at pins 27 and 28 generate noise on pin 22, which is present in the intercarrier signal and passes through the 5.74 MHz filter. Noise on pin 22 inhibits muting. No misinterpretation due to white noise occurs in the stereo decoder; when non-correlated noise masks the identification signal frequencies, which may be present in sustained tone signals. The stereo decoder remains switched to mono.

The series capacitor Cs in the

38.9 MHz resonant circuit provides a notch at the sound carrier frequency in order to provide more attenuation for the sound carrier in the vision carrier reference channel. The ratio of parallel/series capacitor depends on the ratio of VC/SC frequency and has to be adapted to other TV transmission standards if necessary, according to

CPfVCfSC⁄()

-CP.=

The result is an improved “intercarrier buzz” (up to 10 dB improvement in sound channel 2 with 250 kHz video modulation for B/G stereo) or suppression of 350 kHz video modulated beat frequency in the digitally-modulated NICAM subcarrier. The picture carrier for quadrature demodulation in the intercarrier mixer is not exactly 90 degrees due to the shift variation in the integrated phase shift network. The tuning of the LC reference circuit to provide optimal video suppression at the intercarrier output is not the same as that to provide optimal intercarrier buzz suppression. In order to optimize the AF signal performance, a fine tuning for the optimal S/N at the sound channel 2 (from 5.74 MHz) may be performed with a 250 kHz square wave video modulation.

Measurements at the demodulators: For all signal-to-noise measurements the generator must meet the following specifications;

phase modulation errors< 0.5 degree for B/W-jumps intercarrier signal-to-noise ratio as measured with “TV demodulator AMF2” (weighted S/N) must be > 60 dB at 6 kHz sine wave modulation of the B/W-signal.

Signal-to-noise ratios are measured with ∆f=±50 kHz deviation and f

= 1 kHz; with a deviation of

±27 kHz the S/N ratio is deteriorated by 5.3 dB.

January 1992 5

+ 9 hidden pages