The M52761 is IF signal-processing IC for VCRs and TVs. It enable
the PLL detection system despite size as small as that of
conventional quasi-synchronous VIF/SIF detector, IF/RF AGC, SIF
limiter, FM detector, QIF AGC and EQ AMP.
FEATURES
Video detection output is 2V
•
The video detector uses PLL for full synchronous detection
•
circuit. It produces excellent characteristics of DG, DP, 920kHz
beat, and cross color.
•
Dynamic AGC realizes high speed response with double filter.
•
Video IF and sound IF signal processings are separated from
each other. VCO output is used to obtain intercarrier.
This PLL-SPLIT method and built-in QIF AGC provide good
sound sensitivity and reduces buzz.
•
As AFT output voltage uses the APC output voltage, VCO coil is
not used.
•
Audio FM demodulation uses PLL system, so it has wide
frequency range with no external parts and no adjustment.
This IC corresponds to only NTSC system.
•
. It has built-in EQ AMP.
P-P
APPLICATION
TV sets, VCR tuners
PIN CONFIGURATION (TOP VIEW)
RF AGC DELAYEQ F/B
AFT OUT
RF AGC OUT
QIF DET IN
IF AGC FILTER
AUDIO OUT
1
2
3
4
VIF IN
VIF IN
GND
NFB
Outline 20P4B (SP)
20
APC FILTER
19
VIDEO OUT
18
M52761SP/FP
17
Vreg. OUT
165
VCO COIL
VCO COIL
156
Vcc
147
QIF OUT
138
IF AGC FILTER
129
1110
LIMITER IN
20P2N-A (FP)
RECOMMENDED OPERATING CONDITION
In case of Vcc and Vreg. out short
Supply voltage range....................................................4.75 to 5.25V
Vos
V1AF output DC voltage1TP10 SIF IN SG19 SW8=2, V8=0V1.72.32.9V
VoAF1AF output1TP10 SIF IN SG16 SW8=2, V8=0V400560800mVrms
THD AF1 AF output distortion1TP10 SIF IN SG16 SW8=2, V8=0V
LIM1Limiting sensitivity1TP10 SIF IN SG17 SW8=2, V8=0V
AMR1AM rejection1TP10 SIF IN SG18 SW8=2, V8=0V5562
AF S/N 1AF S/N1TP10 SIF IN SG19 SW8=2, V8=0V5562
RINSSIF input resister2TP7−−
CINSSIF input capacitance2TP7−−−
Control section
QIF
C
QIF detection output
amplitude 1
QIF detection output
amplitude 2
SIF detection output
amplitude
QIF control1TP7−−
(cont.)
Test
Test
Input
circuit
point
1TP13
1TP13
1TP13 VIF IN SG15 SW7=2, V7=0V94100106dBµ
VIF IN
QIF IN
VIF IN
QIF IN
point
Input
SG
SG2
SG13
SG2
SG14
Measurement conditionLimits
switches set to position 1
unless otherwise indicated
SW7=2, V7=variable
Min.Typ.Max.
94100106dBµ
94100106dBµ
0.91.52.1kΩ
0.20.9%
4255dBµ
48pF
0.71.0V
Unit
dB
dB
ELECTRICAL CHARACTERISTICS TEST METHOD
Video S/N
Input SG2 into VIF IN and measure the video out (Pin 18) noise in
r.m.s at TP18B through a 5MHz (-3dB) L.P.F.
S/N=20 log
BW Video band width
1. Measure the 1MHz component level of EQ output TP18A with a
spectrum analyzer when SG3 (f2=57.75MHz) is input into VIF
IN. At that time, measure the voltage at TP8 with SW8, set to
position 2, and then fix V8 at that voltage.
2. Reduce f2 and measure the value of (f2-f0) when the (f2-f0)
component level reaches -3dB from the 1MHz component level
as shown below.
TP18
-3dB
0.7×Vo det
NOISE
(dB)
VIN MIN Input sensitivity
Input SG4 (Vi=90dBµ) into VIF IN, and then gradually reduce Vi
and measure the input level when the 20kHz component of EQ
output TP18A reaches -3dB from Vo det level.
VIN MAX Maximum allowable input
1. Input SG5 (Vi=90dBµ) into VIF IN, and measure the level of the
20kHz component of EQ output.
2. Gradually increase the Vi of SG and measure the input level
when the output reaches -3dB.
GR AGC Control range
GR=VIN MAX-VIN MIN (dB)
V3 RF AGC operating voltage
Input SG8 into VIF IN and gradually reduce Vi and then measure
the input level when RF AGC output TP3 reaches 1/2 V
shown below.
TP3
Voltage
3H
V
CC
, as
1/2VCC
1MHz
3
BW
( f2 - f0 )
V
3L
Vi
Vi (dBµ)
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