Contek TA7678 Datasheet
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
BLOCK DIAGRAM
DIP-16
CONTEK
Contek
Contek Microelectronics Co.,Ltd.
http://www.contek-ic.com E-mail:sales@contek-ic.com
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TA7678 LINEAR INTEGRATED CIRCUIT
ABSOLUTE MAXIMUM RATINGS(Ta=25 C)
PARAMETER SYMBOL VALUE UNIT
Supply Voltage Vcc 15 V
Open Loop Voltage V4 15 V
Video DC output current (note) V12 6 V
Operating Temperature Topr -20 to +65 C
Storage Temperature Tstg -55 to 155 C
Power dissipation PD 1.4 W
ELECTRICAL CHARACTERISTICS(Ta=25 C,Vcc=12V,fp=45.75MHz,unless otherwise specified)
PARAMETER TEST
CIRCUIT
Recommended Supply Voltage Vcc 10.8 12 13.2 V
Quiescent circuit current 1 Iccq S1:ON,S3:2,S5:2,S4:1 35 50 65 mA
Video DC output 1 V12 S1:OFF,S3:2,S5:2,S4:1 5.2 5.5 5.8 V
Terminal 5 voltage 1 V5 S1:ON,S3:2,S5:2,S4:1 3.5 4.4 5.3 V
Terminal 7 voltage 1 V5 S1:ON,S3:2,S5:2,S4:1 4.6 6.0 7.2 V
RF AGC Residual Output Voltage 1 V4(sat) S1:OFF,S3:2,S5:2,S4:1 0.5 V
RF AGC Leak Current 1 I4(leak) S1:OFF,S3:1,S5:2,S4:1 1 mA
Video sensitivity 2 SVI Note 1 60 150 250 mVrms
AGC Range 2 V
Sync Tip Level Voltage (pin12) 2 Vsync
Maximum IF Input Voltage 2 VI
White Noise Threshold (pin12) 2 V
White Noise Clamp Level (pin12) 2 V
Black Noise Threshold (pin12) 2 V
Black Noise Clamp Level (pin12) 2 V
Video Frequency Response 3 Gv(IF) Note 6 4.5 5.5 MHz
Suppression of carrier 4 CL Note 7 40 50 dB
Suppression of 2
920kHz Beat level 4 I920 Note 9 33 38 dB
Differentital Gain 5 DG Note 10 7 10 dB
Differential Phase 5 DP Note 10 3.5 5 C
VIF Input Impedance 6 RIN Note 11 1.5 3.0 6.0 k
Maximum Avaliable Current 1 I4(MAX) Note 12 7 mA
RF AGC delay Point Range 2 Vin(delay) Note 13 5.0 7.0 9.0 V
Video output level 2 Vo0 Note 14 2.25 2.5 2.75 V
nd
Carrier 4 I2nd Note 8 40 50 dB
SYMBOL TEST CONDITIONS MIN. TYP. MAX. UNIT
(IF) Note 2 60 64 dB
AGC
Note 3 2.3 2.5 2.7 V
(pin12)
(MAX)
WTH
(pin12)
WCL
(pin12)
BTH
(pin12)
(pin12) Note 5 2.9 3.3 3.7 V
BCL
CIN 3.0 10.0 pF
Note 4 100 120 mVrms
Note 5 5.8 6.2 6.6 V
Note 5 3.7 4.1 4.5 V
Note 5 1.4 1.6 1.8 V
CONTEK
Contek Microelectronics Co.,Ltd.
http://www.contek-ic.com E-mail:sales@contek-ic.com
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TA7678 LINEAR INTEGRATED CIRCUIT
SIF STAGE (Ta=25 C,Vcc=12V,fo=45.75MHz,unless otherwise specified)
PARAMETER TEST
CIRCUIT
SIF Output Voltage 3 VSO Note 15 200 400 600 mVrms
Input limiting voltage 8 Vi(lim) Note 16 200 400 mVrms
AM Rejection Ratio 8 AMR Note 17 40 45 dB
Recovered Output Voltage 8 VOD Note 18 0.5 0.75 Vrms
Total Harmonic distortion 8 THD Note 18 1.0 2.0 %
Maximun Audi Output Voltage 8 VOM Noet 19 4.0 Vp-p
SIF Input Impedance 7 RIN(SIF) 10 20 30 kW
Audio Output Impedance 9 RO(AF) Note 20 10 15 20 kW
Note:
1. V
2. V
3. VIF input : f=45.75MHz CW 15mVrms. Measure the DC level of Pin12.
4. VIF Input : f=45.75MHz APL 100%.87.5% AM Modulation. Pin 14 Open
5. V
=11.5V,VIF Input : 45.5MHz,1kHz,30 AM Modulation. Adjust VIF input Vi level so that the detected output of
AGC
Pin 12 with high impedance probe will be 0.8Vp-p and measure the input Level.
=4V. Measure VIF input level vi is same as note 1 DA=20log(Vi /Vi)(dB)
AGC
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.
=8V. VIF input : f=45.75MHz+-10MHz variable or sweep 15mVrms measure DC level of Pin12.
AGC
SYMBOL TEST CONDITIONS MIN. TYP. MAX. UNIT
CIN(SIF) 3 10 pF
6. V
7. SG1:45.75MHz, 1kHz 80% AM Modulation 100mVrms. SG2 ,SG3:OFF. Setting VAGC so that the output AC
8. Measure 2ndof Pin12 same as note 9.
=8V. SG1:45.75MHz CW. SG2:45.65~27MHz variable.
AGC
6.1. Setting output of SG1 so 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
=F, fBW=45.75-F MHZ
F
SG2
level of Pin12 will be 2.7Vp-p. Measure CL of Pin12 after setting to 0% AM of SG1.
Contek Microelectronics Co.,Ltd.
CONTEK
http://www.contek-ic.com E-mail:sales@contek-ic.com
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