NTE NTE1785 Datasheet

NTE1785

Integrated Circuit

w

TV IF Amp

/Demod and AFC

(For PNP Tuners)

Description:

The NTE1785 is an IF amplifier and demodulator circuit in a 16–Lead DIP type package designed for
use in color and black and white television receivers using PNP tuners.

Features:

D Gain–Controlled Wide–Band Amplifier Providing Complete IF Gain
D Synchronous Demodulator
D White Spot Inverter
D Video Preamplifier with Noise Protection
D AFC Circuit which can be Switched ON/OFF by a DC Level (e.g. During Tuning)
D AGC Circuit with Noise Gating
D Tuner AGC Output (PNP Tuners)
D VCR Switch which Switches Off the Video Output (e.g. For Insertion of a VCR Playback Signal)

Absolute Maximum Ratings:

Supply Voltage, V
Tuner AGC Voltage, V
Total Power Dissipation, P

11–13

4–13

tot

Operating Ambient Temperature Range, T
Storage Temperature Range, T

stg

A

–25° to +60°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

–55° to +125°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

13.2V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

900mW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Characteristics:

Parameter Symbol Test Conditions Min Typ Max Unit

Supply Voltage Range V
IF Input Voltage for Onset of AGC (RMS Value) V
Differential Input Impedance |Z
Zero–Signal Output Level V
Top Sync Output Level V
IF Voltage Gain Control Range G
Bandwidth of Video Amplifier B 3dB – 6 – MHz

(TA = +25°C, V

= 12V, f = 38.9MHz unless otherwise specified)

11–13

11–13

1–16(rms)

| In parallel with 2pF – 2 – kΩ

1–16
12–13
12–13

V

Note 1 – 6 ±0.3 – V

10.2 12.0 13.2 V
– 100 150 µV

2.9 3.07 3.2 V
– 64 – dB

Note 1. So–called “Projected Zero Point”, e.g. with switched demodulator.

Electrical Characteristics (Cont’d): (TA = +25°C, V

= 12V, f = 38.9MHz unless otherwise

11–13

specified)

Parameter Symbol Test Conditions Min Typ Max Unit

Signal–to–Noise Ratio S/N Vi = 10mV, Note 2 – 58 – dB
Differential Gain dG – 4 10 %
Differential Phase – 2 10 deg.
Intermodulation, Blue 1.1MHz, Note 3 – 46 60 dB
Intermodulation, Yellow
Intermodulation 3.3MHz, Note 4 – 46 54 dB
Carrier Signal at Video Output – 4 30 mV
2nd Harmonic of Carrier at Video Output – 20 30 mV
White Spot Inverter Threshold Level – 6.6 – V
White Spot Insertion Level – 4.7 – V
Noise Inverter Threshold Level – 1.8 – V
Noise Insertion Level – 3.8 – V

– 46 50 dB

External Video Switch (VCR) Switched Off V
Tuner AGC Output Current Range I
Tuner AGC Output Voltage V
Tuner AGC Output Leakage Current I
Maximum AFC Output Voltge Swing ∆V

14–13

4

4–13

4

5–13

I4 = 10mA – – 0.3 V
V

14–13

= 11V, V

= 12V – – 15 µA

4–13

– – 1.1 V
0 – 10 mA

10 11 – V
Detuning for AFC Output Voltage Swing ∆f of 10V – 100 200 kHz
AFC Zero–Signal Output Voltage

V

5–13

4 6 8 V

(Minumum Gain)
AFC Switches ON V
AFC Switches OFF V

Note 2. S/N = VO black–to–white/V
Note 3. 20 log (V
Note 4. 20 log (V

at 4.4MHz/VO at 1.1MHz) + 3.6dB.

O

at 4.4MHz/VO at 3.3MHz)

O

n(rms)

6–13
6–13

at B = 5MHz.

3.2 – – V
– – 1.5 V

Pin Connection Diagram

IF Input

Coupling Cap

1
2

16

IF Input
Coupling Cap

15

AGC Delay Input

AGC Output GND

AFC Output

AFC Switch Input

AFC Tank (Sync)

AFC Tank (Amp)

3
4
5
6
7
8

14

AGC Filter

13
12

Video Output
V

11

CC

10

AFC Tank (Sync)

9

AFC Tank (Amp)