TA7678

LINEAR INTEGRATED CIRCUIT

VIDEO AND SOUND IF AMPLIFIER

FOR MONOCHROME TV

RECEIVERS

DESCRIPTION

The Contek TA7678 is a monolithic integrated circuit designed

for the VIF and SIF stage in B/W television receivers. The
UTC TA7678 is used for forward AGC Type.

FEATURE

VIF STAGE
*High gain wide brand IF amplifier 50dB at 45MHz
*Gain reduction with excellent stability: 55dB at 45MHz
*Excellent DG/DP and S/N characteristics
SIF STAGE
*Excellent limiter characteristics
*Excellent AM Rejection
*Large undistorted audio output voltage with

quadrature

detector

DIP-16

BLOCK DIAGRAM

Contek

CONTEK

Contek Microelectronics Co.,Ltd.

http://www.contek-ic.com E-mail:sales@contek-ic.com

TA7678

LINEAR INTEGRATED CIRCUIT

ABSOLUTE MAXIMUM RATINGS

(Ta=25 C)

PARAMETER

SYMBOL

VALUE

UNIT

Supply Voltage

Vcc

Open Loop Voltage

Video DC output current (note)

V12

Operating Temperature

Topr

-20 to +65

Storage Temperature

Tstg

-55 to 155

Power dissipation

1.4

ELECTRICAL CHARACTERISTICS

(Ta=25 C,Vcc=12V,fp=45.75MHz,unless otherwise specified)

PARAMETER

TEST

CIRCUIT

SYMBOL

TEST CONDITIONS MIN. TYP. MAX. UNIT

Recommended Supply Voltage

Vcc

10.8

13.2

Quiescent circuit current

Iccq

S1:ON,S3:2,S5:2,S4:1

Video DC output

V12

S1:OFF,S3:2,S5:2,S4:1

5.2

5.5

5.8

Terminal 5 voltage

S1:ON,S3:2,S5:2,S4:1

3.5

4.4

5.3

Terminal 7 voltage

S1:ON,S3:2,S5:2,S4:1

4.6

6.0

7.2

RF AGC Residual Output Voltage

V4(sat)

S1:OFF,S3:2,S5:2,S4:1

0.5

RF AGC Leak Current

I4(leak)

S1:OFF,S3:1,S5:2,S4:1

Video sensitivity

SVI

Note 1

150

250

mVrms

AGC Range

AGC

(IF)

Note 2

Sync Tip Level Voltage (pin12)

Vsync
(pin12)

Note 3

2.3

2.5

2.7

Maximum IF Input Voltage

(MAX)

Note 4

100

120

mVrms

White Noise Threshold (pin12)

WTH

(pin12)

Note 5

5.8

6.2

6.6

White Noise Clamp Level (pin12)

WCL

(pin12)

Note 5

3.7

4.1

4.5

Black Noise Threshold (pin12)

BTH

(pin12)

Note 5

1.4

1.6

1.8

Black Noise Clamp Level (pin12)

BCL(pin12)

Note 5

2.9

3.3

3.7

Video Frequency Response

Gv(IF)

Note 6

4.5

5.5

MHz

Suppression of carrier

Note 7

Suppression of 2

Carrier

I2nd

Note 8

920kHz Beat level

I920

Note 9

Differentital Gain

Note 10

Differential Phase

Note 10

3.5

VIF Input Impedance

RIN

Note 11

1.5

3.0

6.0

CIN

3.0

10.0

Maximum Avaliable Current

I4(MAX)

Note 12

RF AGC delay Point Range

Vin(delay)

Note 13

5.0

7.0

9.0

Video output level

Vo0

Note 14

2.25

2.5

2.75

CONTEK

Contek Microelectronics Co.,Ltd.

http://www.contek-ic.com E-mail:sales@contek-ic.com

TA7678

LINEAR INTEGRATED CIRCUIT

SIF STAGE

(Ta=25 C,Vcc=12V,fo=45.75MHz,unless otherwise specified)

PARAMETER

TEST

CIRCUIT

SYMBOL

TEST CONDITIONS MIN. TYP. MAX. UNIT

SIF Output Voltage

VSO

Note 15

200

400

600 mVrms

Input limiting voltage

Vi(lim)

Note 16

200

400

mVrms

AM Rejection Ratio

AMR

Note 17

Recovered Output Voltage

VOD

Note 18

0.5

0.75

Vrms

Total Harmonic distortion

THD

Note 18

1.0

2.0

Maximun Audi Output Voltage

VOM

Noet 19

4.0

Vp-p

SIF Input Impedance

RIN(SIF)

CIN(SIF)

Audio Output Impedance

RO(AF)

Note 20

Note:

AGC

=11.5V,VIF Input : 45.5MHz,1kHz,30 AM Modulation. Adjust VIF input Vi level so that the detected output of

Pin 12 with high impedance probe will be 0.8Vp-p and measure the input Level.

AGC

=4V. Measure VIF input level vi is same as note 1 DA=20log(Vi /Vi)(dB)

VIF input : f=45.75MHz CW 15mVrms. Measure the DC level of Pin12.

VIF Input : f=45.75MHz APL 100%.87.5% AM Modulation. Pin 14 Open
4.1. Adjust VIF inpt level 50mVp-p and measure the detected output level Vo(p-p)
4.2. Then increase the input level so that the detected output level will be 1.1* Vo(p-p) and measure the input

level.

AGC

=8V. VIF input : f=45.75MHz+-10MHz variable or sweep 15mVrms measure DC level of Pin12.

AGC

=8V. SG1:45.75MHz CW. SG2:45.65~27MHz variable.

6.1. Setting output of SG1 s o that the DC level of Pin12 will be
6.2. Setting output of SG1(45.65MHz so that the AC level of Pin12 will be 0.5Vp-p.
6.3. Decreasing frequency of SG2 until the AC level of Pin 12 will be 0.35vp-p(-3dB of 0.5Vp-p) then read

SG2

=F, f

=45.75-F MHZ

SG1:45.75MHz, 1kHz 80% AM Modulation 100mVrms. SG2 ,SG3:OFF. Setting VAGC so that the output AC
level of Pin12 will be 2.7Vp-p. Measure CL of Pin12 after setting to 0% AM of SG1.

Measure 2

of Pin12 same as note 9.

CONTEK

Contek Microelectronics Co.,Ltd.

http://www.contek-ic.com E-mail:sales@contek-ic.com

TA7678

LINEAR INTEGRATED CIRCUIT

VAGC=8V. SG1 :45.75MHz(P:picture) 100mVrms, SG2:41.25MHz(S: Sound) 32mVrms(-10dB of
SG1),SG3:42.17MHz(C:Chroma) 32mVrms(-10dB of SG1)
9.1. Setting VAGC so that the output Pin12 will be 3.0V DC.
9.2. Measure the level difference between the C-level and 920kHz.

10. V

AGC

=8V. VIF Input : f=45.75MHz video signal (RAMP) 87.5% AM 100mVp-p. Setting ATT so that the SYNC TIP

level of Pin12 will be 2.5VDC measure DP and DG.

11. V

AGC

=5V. f=45.75MHz. Measure RIN and CIN.

12. S1=ON, S3=2,S5=1,S4=2
13. Pin 14 open. VIF Input : 45.75MHz CW 20mVrms.

13.1. Adjust the voltate of Pin 3 so that the voltage of Pin4 will be 6.0V DC.
13.2. Measure the Pin 3.

14. Pin 14 open. VIF Input: 45 .75MHz 100% APL 87.5% AM Modulation signal amplitude 50mVp-p

mesure the

detected output voltage (white peak to SYNC TIP)

15. PIN14: Op en. SG1 :45.75MHz CW 100mvrms. SG2 :41.25MHz CW 25mVrms. Measre SIF(4.5MHz) output

voltage at Pin12.

16. SIF input: f=4.5MHz FM fMOD=400Hzm Df=+-25kHz

16.1. Adjust SIF input level 100mVp-p and measure the detected output level Vos.
16.2. Then decrease the input level so that the detected output level will be 3dB down of Vos and measure the

input level.

17. SIF input: f=4.5MHz, FM fMOD=400Hz Df=+-25kHz. AM 30%,input level Vins=80dBm.
18. SIF input: f=4.5MHz, fM fMOD=400Hz Df=+-25kHz. Input level Vins=80dBm
19. SIF input: f=4.4~4.6MHz variable or sweep measure the outjput DC voltage change.
20. SIF inptut : f=4.5MHz, FM FMOD=400Hz Df=+-25kHz, input level Vins=80dBm.

20.1. Measure the detected output voltagae vOA with Rx= .
20.2. Then, adjust Rx so that the d etected output voltage will be VOA/2 and measure Rx.

1. DC TEST CIRCUIT

CONTEK

Contek Microelectronics Co.,Ltd.

http://www.contek-ic.com E-mail:sales@contek-ic.com

Электронный компонент: TA7678