LA7577N
SANYO Electric Co., Ltd. Semiconductor Business Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
60597HA(ID) / 11795TH(ID) No. 4037--1/16
Ordering number: EN 4037C
Monolithic Linear IC
Super-split PLL-
II
VIF and SIF
IF Signal Processor for TV/VTRs
Overview
The LA7577N is a high tone quality and high picture qual-
ity, video IF and sound IF IC. It employs split processing
of the video IF signal and sound IF signal using SAW fil-
ters and a PLL detector. Further, the PLL detector incorpo-
rates a buzz canceler for Nyquist buzz interference
suppression to achieve high tone quality.
Functions
VIF stage
VIF amplifier
PLL detector
B/W noise canceler
RF AGC
VCO
Equalizer amplifier
AFT
APC detector
APC filter
Lock detector
IF AGC
Buzz canceler
1st SIF stage
Preamplifier with AGC
1st SIF detector
SIF stage
SIF limiter amplifier
FM quadrature detector
Mute stage
Sound mute (pin 2)
AV mute (pin 4)
IS-15 switch (pin 13)
Features
Employs split processing for wide bandwidth video
characteristics
PLL detector with buzz canceler for excellent buzz and
buzz beat characteristics
APC time constant switch built-in
High-speed AGC supports double time constant method
SIF carrier level AGC in the 1st SIF stage for good SIF
weak electric field characteristics
Good differential gain and phase characteristics
RF AGC easily adjusted using a variable resistor
Package Dimensions
unit: mm
3067-DIP24S
[LA7577N]
Specifications
Absolute Maximum Ratings
at Ta = 25
C
Parameter
Symbol
Conditions
Ratings
Unit
Maximum supply voltage
V
CC
max
13.8
V
Allowable power dissipation
Pd max
Ta
50
C
1200
mW
Circuit voltages
V
3
, V
13
V
CC
V
V
11
V
CC
V
V
23
V
CC
V
LA7577N
No. 4037--2/16
Recommended Operating Conditions
at Ta = 25
C
Electrical Characteristics
at Ta = 25
C, V
CC
= 12V
1. Current flowing into the IC is positive and current flowing out is negative.
Circuit currents
1
I
1
-
1
mA
I
17
-
10
mA
I
21
-
3
mA
I
22
-
2
mA
I
10
3
mA
Operating temperature range
Topg
V
CC
= 9V, Ta =
-
20 to +75
C
-
20 to +70
C
Storage temperature range
Tstg
-
55 to +150
C
Parameter
Symbol
Ratings
Unit
Supply voltage
V
CC
9 or 12
V
Operating supply voltage range
V
CC
op
8.2 to 13.2
V
Parameter
Symbol
Conditions
min
typ
max
Unit
[VIF]
Circuit current
I
9
V
13
= 5V
44
55
68
mA
Quiescent video output voltage
V
21
V
13
= 5V
6.6
7
7.4
V
Maximum RF AGC voltage
V
10H
V
13
= 7V
10.6
11
11.4
V
Minimum RF AGC voltage
V
10L
V
13
= 7V
0
0.5
V
Quiescent AFT voltage
V
14
V
13
= 5V
3.0
5.9
8.0
V
Input sensitivity
V
i
33
39
45
dB/
V
AGC dynamic range
GR
59
65
dB
Maximum allowable input
V
i
max
100
105
dB/
V
Video output amplitude
V
o
(video)
1.95
2.25
2.55
Vp-p
Output signal-to-noise ratio
S/N
49
55
dB
Sync signal tip voltage
V
21
(tip)
V
i
= 10mV
4.15
4.45
4.75
V
920kHz beat level
l
920
P = 0, C =
-
4dB, S =
-
14dB
37
43
dB
Frequency characteristic
f
C
P = 0, S =
-
14dB
6
8
MHz
Differential gain
DG
V
i
= 10mV, 87.5% mod,
f
P
= 58.75MHz
3
6
%
Differential phase
DP
2
5
deg
Maximum AFT voltage
V
14H
11
11.5
12
V
Minimum AFT voltage
V
14L
0
0.4
1.0
V
White-noise threshold voltage
V
WTH
8.9
9.3
9.7
V
White-noise clamp voltage
V
WCL
5.3
5.7
6.1
V
Black-noise threshold voltage
V
BTH
3.4
3.7
4.0
V
Black-noise clamp voltage
V
BCL
5.3
5.7
6.1
V
AFT detector sensitivity
S
f
44
60
84
mV/kHz
VIF-stage input resistance
R
i
(VIF)
f = 58.75MHz
0.8
1.3
1.75
k
VIF-stage input capacitance
C
i
(VIF)
f = 58.75MHz
3.0
6.0
pF
APC pull-in range (U)
f
PU-2
0.6
1.6
MHz
APC pull-in range (L)
f
PL-2
-
1.6
-
0.8
MHz
VCO maximum variation range
f
U
V
18
= 3V
0.6
1.6
MHz
f
L
V
18
= 7V
-
1.6
-
0.8
MHz
Parameter
Symbol
Conditions
Ratings
Unit
LA7577N
No. 4037--3/16
Electrical Characteristics
at Ta = 25
C, V
CC
= 9V
VCO control sensitivity
V
18
= 4.6 to 5V
1.5
3.1
6.2
kHz/mV
[1st SIF]
4.5MHz conversion gain
VG
21
26
31
dB
4.5MHz output level
V
SIF1
V
i
= 10mVrms
50
75
110
mVrms
1st SIF stage maximum input
V
SIF
max
+2.2dB,
-
1dB
60
70
-
mVrms
1st SIF stage input resistance
R
i
(SIF1)
f = 54.25MHz
1.2
2
2.7
k
1st SIF stage input capacitance
C
i
(SIF1)
f = 54.25MHz
3
6
pF
[SIF]
SIF limiting sensitivity
V
i
(lim)
V
13
= 5V
33
39
dB/
V
FM detector output voltage
V
o
V
13
= 5V
400
600
790
mVrms
AM rejection
AMR
V
13
= 5V
40
49
dB
Total harmonic distortion
THD
V
13
= 5V
0.5
1.0
%
SIF signal-to-noise ratio
S/N (SIF)
V
13
= 5V
60
78
dB
[Mute, Defeat]
AFT defeat start voltage
V
D11
0.5
2.3
V
AV mute threshold
V
4TH
0.5
1.9
V
FM mute threshold
V
2TH
0.5
2.0
V
AFT defeat voltage
V
D14
5.4
6
6.6
V
Parameter
Symbol
Conditions
min
typ
max
Unit
[VIF]
Circuit current
I
9
V
13
= 5V
39
48
59
mA
Quiescent video output voltage
V
21
V
13
= 5V
5.0
5.4
5.8
V
Maximum RF AGC voltage
V
10H
V
13
= 7V
7.6
8
8.4
V
Minimum RF AGC voltage
V
10L
V
13
= 7V
0
0.5
V
Quiescent AFT voltage
V
14
V
13
= 5V
2.6
4.5
6.0
V
Input sensitivity
V
i
37
43
49
dB/
V
Video output amplitude
V
o
(video)
1.5
1.75
2.0
Vp-p
Sync signal tip voltage
V
21
(tip)
V
i
= 10mV
3.25
3.55
3.85
V
Maximum AFT voltage
V
14H
8
8.5
9.0
V
Minimum AFT voltage
V
14L
0.3
1.0
V
White-noise threshold voltage
V
WTH
6.8
7.2
7.6
V
White-noise clamp voltage
V
WCL
4.0
4.4
4.8
V
Black-noise threshold voltage
V
BTH
2.5
2.8
3.1
V
Black-noise clamp voltage
V
BCL
2.5
4.1
4.5
V
AFT detector sensitivity
S
f
28
39
55
mV/kHz
[SIF]
FM detector output voltage
V
o
V
13
= 5V
400
600
790
mVrms
[Mute, Defeat]
AFT defeat start voltage
V
D11
0.5
1.6
V
AV mute threshold
V
4TH
0.5
1.1
V
FM mute threshold
V
2TH
0.5
1.9
V
AFT defeat voltage
V
D14
3.9
4.5
5.1
V
Parameter
Symbol
Conditions
min
typ
max
Unit
LA7577N
No. 4037--4/16
Sample Application Circuit (Japan)
LA7577N
No. 4037--5/16
Sample Application Circuit (Japan)
(when the SIF, 1st SIF, AFT and RF AGC are not used)
When the SIF stage is not used
Leave pin 1 open
Tie pin 2 to GND
Leave pin 24 open
When the 1st SIF stage is not used
Connect a 0.01
F capacitor between pin 8 and GND (leave the 0.01
F capacitor on pin 23 connected to GND)
Leave pin 22 open
When the AFT circuit is not used
Tie pins 11 and 12 to GND
Leave pin 14 open
When the RF AGC circuit is not used
Connect a 0.01
F capacitor between pin 4 and GND
Leave pin 10 open
LA7577N
No. 4037--6/16
LA7577N Interface Circuit
LA7577N
No. 4037--7/16
Buzz Canceler
Phase-locked loop (PLL) detectors feature lower harmonic
distortion in the video stage, higher IF phase differential
suppression and much lower audio buzz than conventional
quasi-synchronous detectors. However, voltage-controlled
oscillators (VCO) in PLL detectors, generally, are highly
susceptible to interference from flyback pulses. This inter-
ference can affect the frequency of the VCO, resulting in
added output noise components and audio buzz. This
interference is minimized by VCO supply voltage regula-
tion.
The PLL detector is shown in Figure 1. The automatic
phase control (APC) circuit multiplies the IF signal by the
VCO output signal, which is phase shifted by 90
, to sup-
press the AM component. The APC output is passed
through a low-pass filter to form the VCO control signal.
This results in a signal with a good carrier-to-noise ratio
(C/N).
A simple PLL detector, however, can cause other audio
problems, because the broadcast signal is transmitted
using vestigial sideband modulation. In this case, the RF
signal is converted to an IF signal by the Nyquist slope of
the SAW filter. Since the sidebands in the vicinity of the
Figure 1. PLL detector
picture carrier are attenuated, the magnitudes of the upper
and lower sideband vectors are different. The result is a
phase distortion component,
,in the composite vector as
shown in Figure 2.
Figure 2. Phase noise component
LA7577N
No. 4037--8/16
This phase distortion is the cause of audio buzz, or
Nyquist buzz, because the VCO synchronizes to the com-
posite vector. A Nyquist buzz cancelation circuit is incor-
porated into the LA7577N to reduce the level of this noise
as shown in Figure 3.
A typical signal with Nyquist buzz is shown in Figure 4
together with the compensating signal generated by the
Nyquist-slope canceler and the resultant signal.
Figure 3. PLL detector with buzz cancelation
Figure 4. Nyquist buzz cancelation waveforms
The circuit shown in Figure 3 is highly effective in sup-
pressing audio buzz caused by the 4.5MHz IF beat signal
in Japanese multiplexed (L
-
R) audio or American (MTS)
Multichannel TV Sound (L
-
R) signals.
As buzz cancelation is independent of the PLL loop time
constant, other parameters such as automatic phase control
can be optimized to eliminate interference from flyback
pulses.
Design Notes
FM Detector Output (Pin 1)
The FM detector output is an emitter follower with a
200
series protection resistor as shown in Figure 5.
In multiplex audio applications where pin 1 is connected
to the input of a multiplexed audio decoder, the input
resistance of the decoder can decrease, causing distortion
of the (L
-
R) signal. In this case, a 5.1k
or larger resis-
tor, R1, should be connected between pin 1 and ground.
Figure 5. FM detector output
In monophonic applications, an RC de-emphasis circuit
should be connected as shown in Figure 6. The time con-
stant is given by R2
C.
Figure 6. RC de-emphasis circuit
LA7577N
No. 4037--9/16
FM Discriminator (Pin 2)
The quadrature detector frequency at which the 90
phase
shift occurs is determined by the tuned circuit connected
to pin 2 as shown in Figure 7.
The detector bandwidth characteristics are determined
largely by the coil Q and damping resistance. The damp-
ing resistor should be chosen for the desired output level
and bandwidth characteristics.
FM muting is achieved by holding point A, in Figure 7, at
1V DC.
IF AGC (Pins 3 and 13)
The IF signal is peak detected and averaged by the filters
connected to pins 13 and 3, which are the 1st AGC and
2nd AGC, respectively, as shown in Figure 8. The IF AGC
audio component of the input signal to the video IF stage
is first removed by an audio trap.
Figure 7. FM discriminator
Figure 8. IF AGC circuits
Typical AGC filter time constants
Mute switch (IS-15 switch)
The black-noise canceler can be disabled by pulling pin 13
to 1V or lower. An external AGC source can then be
applied to pin 3 to drive the AGC circuit. This mode of
operation is designed for use with an IS-15 (EIA standard)
switch.
Ghosting problems
Reflected signals which have a phase different from that of
the main signal can cause distortion of the horizontal sync
pulse, as shown in Figure 9. As a result, the same charge-
to-discharge current ratio of the IF AGC cannot be main-
tained. If the phase difference is large, the video signal can
also be distorted as shown in Figure 10. Distortion can be
minimized by connecting a 820k
to 1M
resistor
between pin 13 and ground.
Pin
Component
Single time
constant
Double time constant
3
C1
330pF
330pF
330pF
R1
2.2k
1.8k
C2
0.47
F
0.1
F
13
C3
0.47
F
0.068
F
0.047
F
R2
820k
820k
820k
Figure 9. Horizontal sync pulse distortion
Figure 10. Video signal distortion
LA7577N
No. 4037--10/16
RF AGC Variable Resistor (Pin 4)
The operating point of the RF AGC can be adjusted using
a variable resistor connected to pin 4 as shown in Figure
11. When pin 4 is pulled to 0.5V or lower, both the FM
and video outputs are muted.
VIF Input (Pins 5 and 6)
The VIF amplifier inputs on pins 5 and 6 should be capac-
itively coupled to block DC. The input signal is the aver-
age of the signals on these inputs. The input resistance is
approximately 1.5k
and the input capacitance is approxi-
mately 3pF.
1st SIF Input (Pin 8)
The 1st SIF amplifier input on pin 8, shown in Figure 13,
should be capacitively coupled to block DC. If a SAW fil-
ter is used, an inductor should also be connected as shown
in Figure 14. This matches the SAW filter output capaci-
tance to the LA7577N input capacitance and increases the
sensitivity. The inductor typically would be 0.62
H (for
Japan), 1.0
H (for the USA) or 1.3
H (for PAL countries).
Figure 11. RF AGC adjustment
Figure 12. VIF stage
RF AGC Output (Pin 10)
The RF AGC output on pin 10 is an emitter follower with a
200
series protection resistor as shown in Figure 15. The
value of the bleeder resistor connected between pin 10 and
the tuner, shown in Figure 16, should be chosen based on
the tuner maximum gain.
Figure 13. 1st SIF stage
Figure 14. SAW filter matching
Figure 15. RF AGC output
Figure 16. Bleeder resistor connection
LA7577N
No. 4037--11/16
AFT Tank (Pins 11 and 12)
The automatic frequency tuner (AFT) tank connected to
pins 11 and 12 generates the 90
phase shift required for
quadrature detection. The band-pass frequency character-
istics of the IF SAW filter and the AFT tank are shown in
Figure 17(A) and 17(B), respectively. The combined
response is shown in Figure 17(C). The resulting extended
low-frequency response, which increases susceptibility to
incorrect operation, can be reduced by connecting capaci-
tor C2 in series with the AFT tank as shown in Figure 18.
The resultant frequency response is shown in Figure
17(D).
Capacitors C1 and C2 should have a ratio of approxi-
mately 5 to 1. An inductor or resistor should also be con-
nected in parallel with C2 to maintain the DC balance of
the AFT tank.
The AFT can be defeated by connecting pin 11 to ground
through resistor R1, which should be 20k
or lower.
Figure 17. AFT tank characteristics
AFT Output (Pin 14)
An external bleeder resistor is required to generate the
AFT voltage. The AFT loop time constant is formed by
external resistor R3 and capacitor C2, as shown in Figure
19. The resistor also provides overvoltage protection.
Fluctuations in the AFT quiescent output voltage, if
present in station selector systems using PLLs or voltage
synthesizers, can be reduced by connecting series resistor
R4 as shown in Figure 20. Note, however, that this also
reduces the AFT range.
Figure 18. AFT tank
Figure 19. AFT loop time constant
LA7577N
No. 4037--12/16
VCO Tank (Pins 15 and 16)
The VCO tank circuit is shown in Figure 21. The tank cir-
cuit capacitors connected between pins 15 and 16 should
be in the range 20 to 27pF (24pF is recommended). The
VCO tank susceptibility to external effects can be reduced
by using either chip capacitors or capacitors integrated
with the tank coil.
Figure 20. AFT output
Figure 21. VCO tank
Composite Video Output (Pin 17)
The 4.5MHz composite video output circuit is shown in
Figure 22. A resistor should be connected between this
emitter-follower output and ground to ensure adequate
output drive capability. The resistor should be
1.2k
(V
CC
= 12V), or
1k
(V
CC
= 9V).
APC Filter (Pin 18)
Time-constant switching is incorporated into the VCO for
automatic phase control (APC). When the PLL is locked,
the VCO is controlled by loop A, shown in Figure 23.
When the PLL is unlocked or the signal is weak, the VCO
is controlled by loop B which has higher gain. The
increased APC loop gain also increases the pull-in range.
The recommended range for the external APC filter resis-
tor is 47 to 150
, and for the capacitor, 0.47
F.
Figure 22. Composite video output
Figure 23. APC filter
LA7577N
No. 4037--13/16
Equalization Amplifier (Pins 19 to 21)
The video signal, after passing through the 4.5MHz trap, is
input on pin 19 to the equalization amplifier, and output on
pin 21. A resistor should be connected between the emit-
ter-follower output and ground to ensure adequate output
drive capability. The resistor should be
2.7k
(V
CC
=
12V) or
2.2k
(V
CC
= 9V). A buffer transistor should be
used if the signal is taken off-board.
Equalization amplifier design
The equalization amplifier has an external series resonant
circuit, shown in Figure 24, which controls the frequency
characteristic. The output voltage, V
o
, is given by the fol-
lowing equation:
V
o
= (R1/Z + 1) (V
i
+ V
in
)
Since the input voltage, V
in
, is small, the gain is given
approximately by the following equation:
A
V
= V
o
/V
i
= R1/Z + 1
The amplifier can be used as a voltage amplifier by con-
necting a network to pin 20 as shown in Figure 25. The
bleeder resistor should be chosen to avoid excessive gain
and extreme video sync tip voltages.
Figure 24. Equalization amplifier
Figure 25. Voltage amplifier configuration
External bleeder resistor selection
If the equalization amplifier is configured for non-unity
gain, bleeder resistors R2 and R3, shown in Figure 26, are
required to ensure that the output DC voltage does not
change.
The sync tip voltage does not change if V
X
is approxi-
mately equal to V
21
. V
X
is given by the following equa-
tion:
V
X
= V
CC
R2/(R2 + R3)
The voltage gain is given by:
A
V
= 1 + 1000/Z1
where
Z1 = R2
R3/(R2 + R3)
and resistors R2 and R3 are given by:
R2 = 1000
V
CC
/[(V
CC
-
V
X
)
(A
V
-
1)]
R3 = 1000
V
CC
/[V
X
(A
V
-
1)]
Figure 26. External bleeder resistor circuit
LA7577N
No. 4037--14/16
1st SIF Output (Pin 22)
The 1st SIF output is an emitter follower with internal
100
series resistor as shown in Figure 27. An additional
series resistor should be used for impedance matching to
the ceramic band-pass filter.
1st SIF AGC Filter (Pin 23)
The 1st SIF amplifier has an AGC range of approximately
30dB. The capacitor on pin 23 is normally 0.01
F, but
may, depending on the situation, be as large as 4.7
F
(4.7
F is recommended when using the filter for NICAM
signal processing).
SIF Input (Pin 24)
The input impedance of the amplifier, shown in Figure 29,
is approximately 1k
. Any interference on pin 24, a video
signal for example, can cause audio buzz or heterodyning.
Good circuit board layout is essential. Examples of both
good and poor layout are shown in Figure 30.
Figure 27. 1st SIF output
Figure 28. 1st SIF AGC filter
Figure 29. SIF stage input circuit
Figure 30. PCB layout examples
LA7577N
No. 4037--15/16
Sanyo SAW Filters
Two types of surface acoustic wave (SAW) filter built on
different piezoelectric substrates can be used with the
LA7577N--Lithium Tantalate and Lithium Niobate.
Lithium Tantalate (LiTaO
3
) SAW filters
LiTaO
3
SAW filters have a low temperature coefficient of
-
18ppm/
C and good stability, but have high insertion
loss. An external coil is required at the output for level
matching as shown in Figure 31.
LiTaO
3
SAW filters cover the Japanese and American
bands, which both have relatively high IF frequencies.
These filters have part numbers of the form TSF1
or
TSF2
.
Lithium Niobate (LiNbO
3
) SAW filters
LiNbO
3
SAW filters have a relatively high temperature
coefficient of
-
72ppm/
C, but have an insertion loss
approximately 10dB lower than LiTaO
3
filters. A matching
circuit is, therefore, not required at the output, as shown in
Figure 32. As a result of the lower insertion loss, the pass-
band ripple is higher. However, the low impedance and low
feedthrough of these filters make them less susceptible to
Figure 31. LiTaO
3
SAW filter
stray capacitance effects caused by external components
and PCB layout, resulting in greater stability.
LiNbO
3
SAW filters cover the PAL and American bands,
which have relatively lower IF frequencies. These filters
have part numbers of the form TSF5
.
VCO Tank Circuit
VCO tank circuit with built-in capacitor
When the IC power supply is switched ON, the heat gener-
ated by the IC is conducted by the PCB, including into the
VCO tank. The tank coil legs effectively act as a heatsink
and the heat is dissipated, such that an insignificant amount
of heat is conducted into the VCO tank capacitor. As a
result, the effect on VCO drift is made smaller.
Even so, it is recommended that the inductor and capacitor
be chosen so that their temperature characteristics effec-
tively cancel. Accordingly, it is preferable to use inductors
with low temperature coefficient cores and low tempera-
ture coefficient capacitors.
Figure 32. LiNbO
3
SAW filter
VCO tank circuit with external capacitor
If using an external capacitor, the heat generated by the
IC is conducted by the PCB, including to the external
capacitor. If this happens, the heat affects the capacitor
and changes its capacitance value.
However, because the VCO tank coil is not significantly
affected, the VCO tank tuning point changes.
In this case, it is highly preferable to use inductors with
low temperature coefficient cores and low temperature
coefficient capacitors.
LA7577N
No. 4037--16/16
s
No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment, nuclear
power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or indirectly cause injury,
death or property loss.
s
Anyone purchasing any products described or contained herein for an above-mentioned use shall:
Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors and all their
officers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associated
with such use:
Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on SANYO ELECTRIC CO.,
LTD., its affiliates, subsidiaries and distributors or any of their officers and employees, jointly or severally.
s
Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO
believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of
intellectual property rights or other rights of third parties.
This catalog provides information as of June, 1997. Specifications and information herein are subject to change without notice.
Coil Specifications
Component
Japan
f = 58.75MHz
USA
f = 45.75MHz
PAL countries
f = 38.9MHz
VCO coil
T
1
6T
0.12
C = 24pF
9T
0.12
C = 24pF
11T
0.12
C = 24pF
HW6226-4
HW6227-4
MA6389
AFT coil
T
2
3.5T
0.5
5.5T
0.5
7.5T
0.5
MA8181
MA6343
MA7115
SIF coil
T
4
19T
0.08
C = 100pF
19T
0.08
C = 100pF
25T
0.08
C = 100pF
KS6102-1
KS6102-1
MA8182
VIF SAW filter (Sanyo)
TSF1132L, TSF1137U
TSF1229L, TSF1241U
TSF5315
SIF SAW filter (Sanyo)
TSB1101P
TSB1205P
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