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NTE7018

Integrated Circuit Small–Signal Subsystem for Color TV

NTE Electronics 

DC and AC Electrical Characteristics (Cont’d): (VCC = V7–6 = 12V, TA = +25°C, unless otherwise

specified)

Parameter

Symbol Min Typ Max Unit

Vertical Output (Pin3)

Output Current

Maximum Output Voltage

Feedback Input (Pin4)

I3

–

–

7

mA

V3–6

–

5.7

–

V

Input Voltage (DC Component)

(AC Component (peak–to–peak value))

Input Current

Internal Precorrection to Sawtooth

Deviation Amplitude 50/60HZ

Vertical Guard (Note 12)

V4–6

–

3.3

–

V

V4–6(P–P)

–

1.2

–

I4

–

–

12

µA

∆tp

–

5

–

%

–

0

2

%

Active at a Deviation with Respect to the DC Feedback Level,

∆V4–6

V

(V27–6 = 2.5V),

(at Switching Level Low)

–

1.3

–

(at Switching Level High)

–

1.9

–

Note

1. Pin11 has a double function. When during switch–on 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.

Note 2. Signal with negative–going sync top white 10% of the top sync amplitude.

Note 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.

Note

Note

Note

Note

4. This figure is valid for the complete video signal amplitude (peak white to black).

5. The S/N = 20 log VOUT BLACK–TO–WHITE

VN(RMS) at B = 5MHZ

6. The AFC control voltage is obtained by multiplying the IF–output signal (which is also used to drive the synchro-

nous demodulator) with a reference carrier. This reference carrier is obtained from the demodulator tuned cir-

cuit via a 90° phase shift network. The IF–output 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 10mV and the AFC output loaded with 2

times 220kΩ between +VS and GND. The unloaded Q–factor 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

1.2V and 6.4V. 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 R17–25. A higher resistor value results in a larger value

of the minimum sync pulse amplitude. The slicing level is independent of the video information.

Note

8. Frequency control is obtained by supplying a correction current to the oscillator RC–network via a resistor, con-

nected 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 R23–24.

b) Short circuit the sync separator bias network (Pin25) to +VCC.

To avoid the need of a VCR switch, the time constant of phase detector at strong input signal is sufficient short

to get a stable picture during VCR playback. During the vertical retrace period, the time constant is even shorter

so that the head errors of the VCR 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.

Note 9. The flyback input and sandcastle output have been combined on one pin. The flyback pulse is clamped to a

level of 4.5V. The minimum current to drive the second control loop is 0.1mA.

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