PLESSEY CONSUMER TV CIRCUITS TBA 560 C LUMINANCE AND CHROMINANCE CONTROL COMBINATION The TBASGOC is an integrated circuit for colour television receivers incorporating circuits for the processing and control of the luminance and chrominance signals. ft can be used in conjunction with the TBA520 or TBA99O, 530, 540, 550 and TCA800 integrated circuits. The luminance part provides tuminance delay line matching, DC contrast control, black level clamp circuit, brightness contro! and flyback blanking. The chrominance part provides chroma amplification with ACC, DC chroma gain contro! which tracks with the contrast control, separate saturation control, burst gate, chroma signal flyback blanking colour killer and PAL delay line driver. The TBASBGOC is not an equivalent of the TBA500 and 510 although it performs similar functions to those circuits. ABSOLUTE MAXIMUM RATINGS Voltages are referred to pin 16 Electrical Via max. Supply voltage (note 1) 13.2V My Oto +5V Vig min. 5V Vo Oto +12V (note 2} Viy -5 10 +6V Va Oto +6V Via 3 to +6.5V (note 2} Ve 010 +3V Vigmin. 5V Va 5 ta +8V Vig Oto +5V Currents (positive when flowing into the integrated circuit) yy Ota +ImA Ig -10 ta OmA Iy 1ta +3mA 1qmax +3mA Ig 5 to OmA Igqgmax. +1mA lg bta+ImA Ib5 Ota tImA \y ~3ta +2mA Prormax. Total power dissipation Tamb = 60C {note 1) 580mWw Temperature 558C to +125C ~10C to +60C Storage temperature Operating ambient temperature Notes 1. Permissible during receiver switch on transient V4 ;max. 16V, Propman. 700mW for t > 60sec. 2. V2 and V13 mus: always be lower than V4 BALANCED CHROMA INPUT ow DC CONTRAST CONTROL @ALANCED CHAOMA INPUT LUMINANCE INPUT ACE INPUT BLACK LEVEL CLAMP CAPACIFOR CHROMA SATURATION CONTROL LUMINANCE OUTPUT DC FEEOBACK FOR CHROMA CHARNEL BRIGHTNESS CONTROL Vee SUAST OUTPUT BUAST GATE AND CLAMPING PULSE 1:7 FLYBACK BLANKING WAVEFORM CHAOMA OUTPUT OP16 Fig. t Pin connections QUICK REFERENCE DATA BM Supply Voltage (Nom.) (V41-16) 12V W Supply Current {Nom.) (111) 30mMA WM Luminance Signal Input Current (Typ.) (14{p-p)} 0.4mA W Luminance Output Signal at Nomina Contrast Setting (Typ.) and Input Current as Above (V5.16(p-p}) 1V (See Note 1} HB Chrominance Input Signal (Min.) (V1.15(p-p)) 4mV @ = Chrominance Input Signa! (Max.) V1.15p-p}) B8OmvV @ 3 Chrominance Output Signal at Nominal Contrast and Saturation Setting (Typ.) (V9.16(p-p}) 1V (See Note 1} Contrast Control Range > 20d8 Saturation Control Range >20dB Burst Output (Closed ACC Loop} (Typ) (V7-16(p-p)} 1V 217TBAS60C 2 CONTRAST CONTROL atc AMPLIFIER PTT TT eS eee eee eee eer aml BLANKING Jano cat | | AMPLIFIER mane AND OUTPUT ELECTRICAL CHARACTERISTICS Test Conditions (unless otherwise stated): Fig. 2. TBASGOC block diagram Vec = +12V, Tamb = +25C test circuit = Fig. 6, voltages referred to pin 16 Value Characteristic Pin Units Conditions Min. Typ. } Max, Supply voltage, Vcc 11 10.8 12 13.2 v Required Input Signals Chrominance input signal, p-p value of colour bars with 75% saturation, V;.15 | 1,15 4 80 |mVp-p Luminance input current, black-to-white 3 0.4 15 |mAp-p Contrast control voltage range for 20d8 control 2 2 3.7 5.6 V |See note 1 and Fig. 3 Brightness control voltage for black level of 1.5V at O/P 6 1.3 V_ |See note 2 and Fig. 4 Saturation control voltage range 20dB control 13 2.7 4.4 6.2 V_ {See note 1 and Fig. 5 Flyback blanking pulse amplitude 8 far OV blanking level at pin 5 0 -0.5 -1 V pk for 1.5V blanking level at pin -2 -2.5 -3 V pk Burst keying (back porch) pulse (+ve going} 10 0.05 3 mA pk Colour killer 13 0.5 1 v Automatic chrominance control starting level (ve going) 14 1.2 V_|See note 3 Obtainable Output Signals Luminance output voltage (black-to-white}| 5 1 3 V p-p [fg = 0.4mA p-p, V2 =3.7V Black level shift 100 mV |See notes 1 and 4 Burst signal amplitude 7 1 Vp-p Chrominance signal at nominal contrast and saturation 9 1 V p-p |See note 1 3dB bandwidth of chrominance and luminance amplifier 5 MHz Change of ratio of luminance to chrominance 2 dB {Contrast control 10dB NOTES Nominal contrast or saturation = maximum value 6dB. Thus, the control is +6 to 14dB on the naminat When Vg is increased to above 1,7V, the black level of the output signal remains at 2.7V A negative-going potential provides a 26dB ACC range with negligible signat distortion. Maximum gain reduction is obtained at an input 1 2. 3 4. voltage of 500mV min. Black jevel shift is specified as that due to changes of contrast and video content at constant brightness setting. 218FUNCTIONAL DESCRIPTION 1. Balanced Chroma Signal Input (in conjunction with pin 15} This is derived from the chroma signal bandpass filter, designed to provide a push-pull input. An input signal amplitude of at least 4mV peak-to-peak is required between pins 1 and 15. Both pins require DC potential of approximately +3,0V. This is derived as a common mode signal from a network connected to pin 7 (burst output). In this way OC feedback is provided over the burst channel to stabilise its operation. All figures for the chrominance signal are based on a colour bar signal with 75% saturation; /.e., burst-to-chroma ratio of input signal is 1:2. 2. DC Contrast Cantrol With +3.7V on this pin, the gain in the luminance channei is such that a 0.4mA black-to-white input signal to pin 3 gives a luminance output signal amplitude on pin & of 1V black-to-white. A variation of voltage on pin 2 between +5.6V and +2V gives a corresponding gain variation of +6 to >-14d8. A similar variation in gain in the chroma channel occurs in order to provide the correct tracking between the two signals. Beam current limiting can be applied via the contrast control network as shown in the peripheral circuit, when a separate overwind is available on the line output transformer. 3. Luminance Signal input This terminai has a very low input impedance and acts as a current sink. The luminance signal from the delay line is fed via a series terminating resistor and a DC blocking capacitor and requires to be about 0.4mA peak-to-peak amplitude. A DC bias current is required via a 12kQ resistor to the +12 fine. 4. Charge Storage Capacitor for Black Level Clamp &. Luminance Signal Output An emitter follower provides a low impedance output signal of 1V black-to-white amplitude at nominal contrast setting having a nominal black jevel in the range 0 to +2.7V. An external emitter load resistor is required, not less than 1kQ. Hf a greater luminance output is required than 1V, with normal control settings, the input current swing at pin 3 should be increased in proportion. 6. Brightness Control Over the range of potential +0.9 to +1.7V the biack level of the juminance output signal (pin 5) is increased from 0 to +2.7V. The output signal black level remains at +2.7V when the potential on pin 6 is increased above +1.7V. 7. Burst Output A 1V_ peak-to-peak burst (controlled by the ACC system} is produced here. Alsa, to achieve gaod DC stability by negative feedback in the burst channel the DC potential at this pin is fed back to pins 1 and 15 via the chroma input transformer. TBAS60C 8. Flyback Blanking Input Waveform Negative going horizontal and vertical blanking pulses may be applied here. If rectangular blanking pulses of not greater than 1V negative excursion, or DC coupled pulses of similar amplitude whose negative excursion is at zero volts DC are applied, the signal level at the luminance output (pin 5) during blanking will be OV. However, if the blanking pulses applied to pin 8 have an amplitude of 2 to 3V the signal level at the juminance output during blanking will be +1.5V. The negative pulse amplitude should not exceed 5V. 9, Chroma Signal Output With a 1V peak-to-peak burst output signal (pin 7) and at nominal contrast and saturation setting (pins 2 and 13) the chroma signal output amplitude is 1V peak-to-peak. An external network is required which provides DC negative feedback in the chrama channel via pin 12. 10. Burst Gating and Clamping Pulse Input A positive pulse of not less than SQuA is required on this pin to pravide gating in the burst channel and luminance channel biack-tevel clamp circuit. The timing and width of this current pulse shauld be such that no appreciable encraachment occurs into the sync. pulse or piciure line periods during normal operations of the receiver. 11. +12V Supply (Vec) Correct operation occurs within the range 10.8 to 13.2V. All signal and control levels have a linear dependency on supply voltage but, in any given receiver design this range may be restricted due to considerations of tracking between the power supply variations and picture contrast and chroma levels. The power dissipation must not exceed 580mW at 60C ambient temperature. 12. DC Feedback for Chroma Channel (see pin 9} 13, Chroma Saturation Control A cantrol range of +6dB to>14dB is provided over a range of OC potential on pin 13 from 6.2 to 2.7V. Colour killing is also achieved at this terminal by reducing the DC potential ta less than +1V, e.g., from the TBA540 colour killer output terminal. The minimum kili factor is 40dB. 14. ACC Input A negative going potential gives an ACC range of about 26dB starting at +1.2V. From 1V to 800mV the steepest part of the characteristic occurs, but a smal! amount of gain reduction also occurs from BOOmV to 500mvV. The input resistance is at least 50k22. 15. Chroma Signal Input (see pin 1) 16. Negative Supply, OV (Earth) 219TBAS560C G (eo) LOTS OF Vo.5 AT WHICH 50% GAIN REDUCTION 1S LNOMINAL CONTRAST) 2s s Vo-15 (WI Fig. 3. Cantrast contro! characteristic (luminance amplifier) = 5 18 z c < g > 0 f LMITS. OF Wis iy SOL ay WICH, 30% = 5 a a 6 1 2 o Vo-16 () Viy-15 (YD Fig. 4 Control of black level at output Fig. 5 Chrominance amplifier saturation of furninance amplifier characteristic COMPOSITE VIDEO INPUT FROM TCA270 BEAM CURRENT LIMITING INPUT EARTHY ENO OF EHT OVER WIND) QRIGHINESS CONTROL LUMINANCE LO MaTAnK aL ANKING para d DELAY LINE BURST OUTPUT CONTRAST BLANKING CONTROL ANO OUTPUT TBASEOC AMPLIFIER LEVEL FOR AMPLIFIER act AMPLIFIER AND OUTPUT BURST GATE AND OUTPUT CHROMA OUTPUT BACK PORCH AU PULSE COLOUR KILLER ACC FROM TBASLO 220 Fig. & Application diagram