NTE7018 Integrated Circuit Small Signal Subsystem for Color TV

Transcription

1 NTE7018 Integrated Circuit SmallSignal Subsystem for Color T Description: The NTE7018 is a T subsystem circuit intended to be used for baseband demodulation applications. This circuit consists of all smallsignal functions (except the tuner) required for a quality color television receiver. The only additional circuits needed to complete a receiver are a tuner, the deflection output stages, and a color decoder. The NTE1567 NTSC color decoder, and the NTE1754 vertical output, are ideal complements for the NTE7018. Features: ision IF amplifier with synchronous demodulation Tuner AGC (negativegoing control voltage with increasing signal) AGC detector for negative modulation AFC circuit ideo preamplifier Sound IF amplifier, demodulator, and preamplifier DC volume control Horizontal synchronization circuit with two control loops Extra time constant switches in the horizontal phase detector ertical synchronization (divider system) and sawtooth generator with automatic amplitude adjustment for or 60H Z Three level sandcastle pulse Applications: Color television receiver CAT converters Baseband processing Absolute Maximum Ratings: Supply oltage (Pin7), CC Total Power Dissipation, P TOT W Operating Ambient Temperature Range, T A to +65 C Storage Temperature Range, T stg to +1 C

2 DC and AC Electrical Characteristics: ( CC = 76 = 12, T A = +25 C, unless otherwise specified) Supplies Supply oltage (Pin7) Supply Current (Pin7) I ma Supply oltage (Pin11, 1) Supply Current (Pin11) for Horizontal Oscillator Start I ma ision IF Amplifier (Pin8 and Pin9) Input Sensitivity (38.90MH Z on set AGC) (45.75MH Z on set AGC) Differential Input Resistance (Pin8 and Pin9) R Ω Differential Input Capacitance (Pin8 and Pin9) C 89 5 pf Gain Control Range G Maximum Input Signal m Expansion of Output Signal for ariation of Input Signal with 89 at 1µ (0) µ ideo Amplifier (measured at top sync input signal voltage (RMS value) of 10m) Output Level for Zero Signal Input 176 (Zero Point of Switched Demodulator) 5.8 Output Signal Top Sync Level ( 2) Amplitude of ideo Output Signal (PeaktoPeak alue) 176(PP) 2.6 Internal Bias Current of Output Transistor (NPN EmitterFollower) I 17(INT) ma Bandwidth of Demodulated Output Signal BW 5 MH Z Differential Gain ( 3) G % Differential Phase ( 3) ϕ 3 10 deg. ideo NonLinearity Complete ideo Signal Amplitude ( 4) 10 % Intermodulation at Gain Control = 45 f = 1.1MH Z ; blue f = 1.1MH Z ; yellow f = 3.3MH Z ; blue f = 3.3MH Z ; yellow SignaltoNoise Ratio ( 5) Z S = 75Ω, I = 10m end of Gain Control Range Residual Carrier Signal 7 30 m Residual 2 nd Harmonic of carrier Signal m Tuner AGC ( 13) Minimum Starting Point TakeOver 16(RMS) 0.5 m Maximum Starting Point takeover 16(RMS) 100 m Maximum Output Swing I 5MAX 6 8 ma Output Saturation oltage (I = 2mA) 56(SAT) 300 m Leakage Current I 5 1 µa Input Signal ariation Complete Tuner Control ( I 5 = 2mA) I AFC Circuit (Pin18, 6) AFC Output oltage Swing 186(PP) Available Output Current ±I ma S/N

3 DC and AC Electrical Characteristics (Cont d): ( CC = 76 = 12, T A = +25 C, unless otherwise specified) AFC Circuit (Cont d) (Pin18, 6) Control Steepness 70 m/ kh Z Output oltage at Nominal Tuning of the ReferenceTuned Circuit Offset Current AFC Output (Pin20 and Pin21 ShortCircuited) I 18 TBD µa Sound Circuit Input Limiting oltage ( O = O MAX 3, Q L = 16, f AF = 1kH Z, f C = 5.5MH Z ) 15LIM Input Resistance ( I(RMS) = 1m) R kω Input Capacitance ( I(RMS) = 1m) C pf AM Rejection ( I = 10m) ( I = m) AMR 46 AF Output Signal ( f = 7.5kH Z, Minimum Distortion) ( f = kh Z, Pin11 used as Starting Pin) 126(RMS) AF Output Impedance Z Ω Total Harmonic Distortion olume Control 20, ( f = 27.5kH Z, Weighted Acc. CCIR 468) Ripple Rejection (f k = 100H Z, olume Control 20) (When Muted) THD RR 1 3 Output oltage in Mute Condition SignaltoNoise Ratio ( f = 27.5kH Z Weighted Noise, CCIR 468) S/N 45 olume Control oltage (Pin11 Disconnected) Circuit (Pin11 Short Circuited) I ma External Control Resistor R kω Suppression Output Signal During Mute Condition OSS 66 Sync Separator and First Control Loop Required Sync Pulse Amplitude (R 1725 = 2kΩ, 7) 256(PP) m Input Current ( 256 > 5) ( 256 = 0) I 25 Holding Range PLL ± f H Z Catching Range PLL ± f H Z Control Sensitivity ( 8) (ideo to Oscillator, at Weak Signal) (at Strong Signal During Scan) (During ertical Retrace and Catching) kh Z /µs Second Control Loop (Positive Edge) TBD Control Sensitivity (R 286 = 47kΩ Trim Pot) t D / t O Control Range t D 25 µs Phase Adjustment (ia Second Control Loop) Control Sensitivity 25 µa/µs Maximum Allowed Phase Shift a ±2 µs µ m % µa ma

4 DC and AC Electrical Characteristics (Cont d): ( CC = 76 = 12, T A = +25 C, unless otherwise specified) Horizontal Oscillator (Pin23) FreeRunning Frequency (R = 34kΩ, C = 2.7nf) f FR 15,625 H Z Spread with Fixed External Components f % Frequency ariation due to Change of Supply oltage from 9.5 to 13.2 f FR % Frequency ariation with Temperature TC 1 x 10 4 C 1 Maximum Frequency Shift f FR 10 % Maximum Frequency Deviation at Start HOut f FR 8 10 % Horizontal Output (Pin26) Output oltage (High Level) (at which Protection Commences) (Low, I 26 = 10mA) Duty Cycle of Horizontal Output Signal (t p = 10µs) d 0.45 Rise Time of Output Pulse t R 260 ns Fall Time of Output Pulse t F 100 ns Flyback Input and Sandcastle Output ( 9) Input Current Required During Flyback Pulse I ma Output oltage (During Burst Key Pulse) (During Horizontal Blanking) (During ertical Blanking) Width of Burst Key Pulse (60H Z ) (H Z ) Width of Horizontal Blanking Pulse Width of ertical Blanking Pulse (H Z Divider in Search Window) (60H Z Divider in Search Window) (H Z Divider in Narrow Window) (60H Z Divider in Narrow Window) Delay Between Start of Sync Pulse at ideo Output and Rising Edge of Burst Key Pulse Coincidence Detector Mute Output ( 10) t W Flyback Pulse Width µs lines 5.2 µs oltage for InSync Condition oltage for NoSync Condition, No Signal Switching Level to Switch Off the AFC Hysteresis AFC Switch Switching Level to Activate Mute Function (Transmitter Identification) Hysteresis Mute Function Charge Current in Sync Condition 4.7µs I 22(PP) ma Discharge Current in Sync Condition 1.3µs I 22(PP) 0.5 ma ertical Ramp Generator ( 11) Input Current During Scan I µa Discharge Current During Retrace I ma Sawtooth Amplitude 26(pP)

5 DC and AC Electrical Characteristics (Cont d): ( CC = 76 = 12, T A = +25 C, unless otherwise specified) ertical Output (Pin3) Output Current I 3 7 ma Maximum Output oltage Feedback Input (Pin4) Input oltage (DC Component) (AC Component (peaktopeak value)) 46 46(PP) Input Current I 4 12 µa Internal Precorrection to Sawtooth t p 5 % Deviation Amplitude /60H Z 0 2 % ertical Guard ( 12) Active at a Deviation with Respect to the DC Feedback Level, ( 276 = 2.5), (at Switching Level Low) (at Switching Level High) Pin11 has a double function. When during switchon a current of 6mA is supplied to this pin, this current is used to start the horizontal oscillator. The main supply can then be obtained from the horizontal deflection stage. When no current is supplied to this pin it can be used as volume control. The indicated maximum value is the current at which all IC s will start. Higher currents are allowed: the excess current is bypassed to GND. 2. Signal with negativegoing sync top white 10% of the top sync amplitude. 3. 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. The differential phase is defined as the difference in degrees between the largest and smallest phase angle. 4. This figure is valid for the complete video signal amplitude (peak white to black). OUT BLACKTOWHITE 5. The S/N = 20 log N(RMS) at B = 5MH Z 6. The AFC control voltage is obtained by multiplying the IFoutput signal (which is also used to drive the synchronous demodulator) with a reference carrier. This reference carrier is obtained from the demodulator tuned circuit via a 90 phase shift network. The IFoutput signal has an asymmetrical frequency spectrum with respect to the carrier frequency. To avoid problems due to this asymmetrical signal, the AFC circuit is gated by means of an internally generated gating pulse. As a result the detector is operative only during black level at a constant carrier amplitude which contains no additional side bands. As a result the AFC output voltage contains no video information. At very weak input signals, the driver signal for the AFC circuit will contain a lot of noise. This noise signal has again an asymmetrical frequency spectrum and this will cause an offset of the AFC output voltage. To avoid problems due to this effect, the AFC is switched off when the AGC is controlled to maximum gain. The measured figures are obtained at an input sign RMS voltage of 10m and the AFC output loaded with 2 times 220kΩ between + S and GND. The unloaded Qfactor of the reference tuned circuit is 70. The AFC is switched off when no signal is detected by the coincidence detector or when the voltage at Pin22 is between 1.2 and 6.4. This can be realized by a resistor of 68kΩ connected between Pin22 and GND. 7. The slicing level can be varied by changing the value of R A higher resistor value results in a larger value of the minimum sync pulse amplitude. The slicing level is independent of the video information. 8. Frequency control is obtained by supplying a correction current to the oscillator RCnetwork via a resistor, connected between the phase 1 detector output and the oscillator network. The oscillator can be adjusted to the right frequency in one of the two following ways: a) Interrupt R b) Short circuit the sync separator bias network (Pin25) to + CC. To avoid the need of a CR switch, the time constant of phase detector at strong input signal is sufficient short to get a stable picture during CR playback. During the vertical retrace period, the time constant is even shorter so that the head errors of the CR are compensated at the beginning of the scan. Only at weak signal conditions (information derived from the AGC circuit) is the time constant increased to obtain a good noise immunity. 9. The flyback input and sandcastle output have been combined on one pin. The flyback pulse is clamped to a level of 4.5. The minimum current to drive the second control loop is 0.1mA.

6 10. The functions insync/outofsync and transmitter identification have been combined on this pin. The capacitor is charged during the sync pulse and discharged during the time difference between gating and sync pulse. 11. The vertical scan is synchronized by means of a divider system. Therefore no adjustment is required for the ramp generator. The divider detects whether the incoming signal has a vertical frequency of or 60H Z and corrects the vertical amplitude. 12. To avoid screenburn due to a collapse of the vertical deflection, a continuous blanking level is inserted into the sandcastle pulse when the feedback voltage of the vertical deflection is not within the specified limits. 13. Starting point tuner takeover at 1 = 0.2mA. Takeover to be adjusted with a potentiometer of 47kΩ. Pin Connection Diagram AGC Takeover 1 28 Phase 2 Detector ertical Ramp Generator ertical Drive Sandcastle Output/ Feedback Input Horizontal Drive ertical Feedback 4 25 Sync Separator Tuner AGC 5 24 Phase 1 Detector GND 6 23 Horizontal Oscillator CC 7 22 Coincidence Detector Decouple ision IF Input ision IF Input Decouple Capacitor olume Control/ Start Horizontal Oscillator Audio Output Sync Demodulator 20 Sync Demodulator 19 AGC Detector 18 AFC Output 17 ideo Output Sound Demodulator GND Sound IF Decouple Sound IF Input (37.32) Max.540 (13.7).2 (6.35).100 (2.54) (33.02).122 (3.1) Min.600 (15.24)