SANYO LA1784

Ordering number : ENN6039
Monolithic Linear IC
LA1784M
Single-Chip Tuner IC for Car Radios
The LA1784M integrates all six blocks required in a car
radio tuner on a single chip.
Functions
• FM front end
• FM IF
• Noise canceller
• Multiplex
• AM up-conversion
• FM/AM switch
• MRC
Features
Package Dimensions
Unit:mm
3159-QIP64E
[LA1784M]
0.8
1.0
17.2
14.0
0.35
1.6
1.0
0.15
33
48
32
49
17
64
1
16
15.6
3.0max
Independent IC
0.8
Mounted on a 40 × 80 × 1.3 mm3
glass epoxy printed circuit board
1.0
Allowable power dissipation,
Pdmax — mW
17.2
14.0
• Improved noise reduction methods
— The FM front end provides excellent 3-signal
characteristics equivalent to those of the LA1193M.
— Superlative listenability due to improved medium and
weak field noise canceller characteristics.
— Improved separation characteristics
— Anti-birdie filter
— Improved AM and FM thermal characteristics
— Excellent FM signal meter linearity
— Modified N.C. circuit for improved noise rejection
• Double conversion AM tuner (up conversion)
Reduces the number of external components required as
compared to earlier double conversion tuners, in
particular, no crystal is required (when used in
conjunction with the LC72144).
• Sample-to-sample variation reduction circuit built into
the FM IF circuit.
(Fixed resistors are used for the SD, keyed AGC, mute
on adjustment, ATT, SNC, and HCC functions.)
• The LA1784 inherits the block arrangement of the
LA1780M and supports pin-compatible designs.
1.6
1.0
Overview
0.1
2.7
0.8
SANYO: QIP64E
Ambient temperature, Ta — °C
Any and all SANYO products described or contained herein do not have specifications that can handle
applications that require extremely high levels of reliability, such as life-support systems, aircraft’s
control systems, or other applications whose failure can be reasonably expected to result in serious
physical and/or material damage. Consult with your SANYO representative nearest you before using
any SANYO products described or contained herein in such applications.
SANYO assumes no responsibility for equipment failures that result from using products at values that
exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other
parameters) listed in products specifications of any and all SANYO products described or contained
herein.
SANYO Electric Co.,Ltd. Semiconductor Company
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110-8534 JAPAN
61501TN (OT) No. 6039-1/50
LA1784M
Specifications
Maximum Ratings at Ta = 25°C
Parameter
Symbol
Maximum supply voltage
Allowable power dissipation
Conditions
VCC1 max
Pins 6, 40, and 61
VCC2 max
Pins 7, 45, 54, 59, and 60
Pd max
Ratings
Unit
9
Ta ≤ 55°C
V
12
V
950
mW
Operating temperature
Topr
–40 to +85
°C
Storage temperature
Tstg
–40 to +150
°C
Operating Conditions at Ta = 25°C
Parameter
Symbol
VCC
Recommended supply voltage
VCCST IND
Operating supply voltage range
Conditions
Ratings
Unit
Pins 6, 7, 40, 45, 54, 59, 60, and 61
8
V
Pin 26
5
V
7.5 to 9.0
V
VCC op
Operating Characteristics at Ta = 25°C, VCC= 8.0V, in the specified test cricuit for the FM IF input
Ratings
Parameter
Symbol
Conditions
min
typ
max
unit
[FM Characteristics] At the FM IF input
Current drain
Demodulation output
Pin 31 demodulation output
Channel balance
Total harmonic distortion
ICCO-FM
VO-FM
VO-FM31
CB
No input, I40 + I45 + I54 + I59 + I60 + I61
60
94
110
mA
10.7 MHz, 100dBµ, 1 kHz, 100%mod, The pin 15 output
205
310
415
mVrms
10.7 MHz, 100dBµ, 1 kHz, 100%mod, The pin 31 output
190
295
380
mVrms
The ratio between pins 15 and 16 at 10.7 MHz, 100 dBµ, 1 kHz
–1
0
+1
dB
0.3
1
THD-FM mono
10.7 MHz, 100 dBµ, 1 kHz, 100% mod, pin 15
Signal-to-noise ratio: IF
S/N-FM IF
10.7 MHz, 100 dBµ, 1 kHz, 100% mod, pin 15
75
82
dB
AM suppression ratio: IF
AMR IF
10.7 MHz, 100 dBµ, 1 kHz, fm = 1 kHz, 30% AM, pin 15
55
68
dB
Att-1
10.7 MHz, 100 dBµ, 1 kHz. The pin 15
attenuation when V33 goes from 0 to 2 V
5
10
15
dB
Att-2
10.7 MHz, 100 dBµ, 1 kHz. The pin 15
attenuation when V33 goes from 0 to 2 V*1
15
20
25
dB
Att-3
10.7 MHz, 100 dBµ, 1 kHz. The pin 15
attenuation when V33 goes from 0 to 2 V*2
28
33
38
dB
10.7 MHz, 100 dBµ, L+R = 90%, pilot = 10%. The pin 15 output
ratio
30
40
Muting attenuation
Separation
Separation
Stereo on level
ST-ON
The pilot modulation such that V26 < 0.5 V
2.1
4.1
Stereo off level
ST-OFF
The pilot modulation such that V26 > 3.5 V
1.2
3.1
Main total harmonic distortion
THD-Main L
10.7 MHz, 100 dBµ, L+R = 90%, pilot = 10%. The pin 15 signal
Pilot cancellation
PCAN
10.7 MHz, 100 dBµ, pilot = 10%.
The pin 15 signal/the pilot level leakage. DIN audio
SNC output attenuation
AttSNC
10.7 MHz, 100 dBµ, L-R = 90%, pilot = 10%.
V28 = 3 V → 0.6 V, pin 15
%
dB
6.5
%
%
0.3
1.2
%
20
30
dB
1
5
9
dB
0.5
4.5
8.5
dB
AttHCC-1
10.7 MHz, 100 dBµ, 10 kHz, L+R = 90%, pilot = 10%.
V29 = 3 V → 0.6 V, pin 15
AttHCC-2
10.7 MHz, 100 dBµ, 10 kHz, L+R = 90%,
pilot = 10%. V29 = 3 V → 0.1 V, pin 15
6
10
14
dB
100 dBµ, 10.7 MHz, 30% modulation. The IF input such
that the input reference output goes down by 3 dB
33
40
47
dBµ
The IF input level (unmodulated) when V33 = 2 V
27
35
43
dBµ
The IF input level (unmodulated) (over 100 mV rms)
such that the IF counter buffer output goes on
54
62
70
dBµ
54
62
70
dBµ
VIFBUFF-FM
10.7 MHz, 100 dBµ, unmodulated. The pin 23 output
130
200
270
mVrms
VSM FM-1
No input. The pin 24 DC output, unmodulated
0.0
0.1
0.3
V
VSM FM-2
50 dBµ. The pin 24 DC output, unmodulated
0.4
1.0
1.5
V
VSM FM-3
70 dBµ. The pin 24 DC output, unmodulated
2.0
2.7
3.5
V
VSM FM-4
100 dBµ. The pin 24 DC output, unmodulated
4.7
5.5
6.2
V
Muting bandwidth
BW-mute
100 dBµ. The bandwidth when V33 = 2 V, unmodulated
150
220
290
kHz
Mute drive output
VMUTE-100
100 dBµ, 0 dBµ. The pin 33 DC output, unmodulated
0.00
0.03
0.20
V
HCC output attenuation
Input limiting voltage
Muting sensitivity
SD sensitivity
Vi-lim
Vi-mute
SD-sen1 FM
SD-sen2 FM
IF counter buffer output
Signal meter output
Continued on next page.
No. 6039-2/50
LA1784M
Continued from preceding page.
Ratings
Parameter
Symbol
Conditions
min
typ
max
unit
[FM FE Mixer Input
N-AGC on input
VN-AGC
83 MHz, unmodulated.
The input such that the pin 2 voltage is 2.0 V or below
81
88
95
dBµ
W-AGC on input
VWAGC
83 MHz, unmodulated. The input such that the pin 2
voltage is 2.0 V or below. (When the keyed AGC is set to 4.0 V.)
104
110
116
dBµ
83 MHz, 80 dBµ, unmodulated. The FE CF output
19
30
48
mVrms
No input
85
110
165
mVrms
Conversion gain
Oscillator buffer output
A.V
VOSCBUFFFM
[NC Block] NC input (pin 30)
Gate time
τGATE1
Noise sensitivity
NC effect
SN
SN-NC
f = 1 kHz, for a 1-µs, 100-mV p-o pulse
55
µs
The level of a 1 = kHz, 1-µs pulse input that starts
noise canceller operation. Measured at pin 30.
40
mVp-o
The pulse rejection effect provided by the noise canceller.
For a repeated 1-µs wide pulse, frequency = 10 kHz,
150 mV p-o. The ratio of the FM mode pin 15 output
referenced to the AM mode pin 15 output (effective value)
5
[Multipath Rejection Circuit] MRC input (pin 27)
MRC output
MRC operating level
VMRC
MRC-ON
V24 = 5 V
2.2
2.3
2.4
V
The pin 32 input level at f = 70 kHz such that
pin 24 goes to 5 V and pin 27 goes to 2 V
10
15
20
mVrms
[AM Characteristics] AM ANT input
Practical sensitivity
S/N-30
1 MHz, 30 dBµ, fm = 1 kHz, 30% modulation, pin 15
20
Detector output
VO-AM
1 MHz, 74 dBµ, fm = 1 kHz, 30% modulation, pin 15
130
195
270
mVrms
VO-AM31
1 MHz, 74 dBµ, fm = 1 kHz, 30% modulation, pin 31
110
175
230
mVms
VAGC-FOM
1 MHz, 74 dBµ, referenced to the output, the input amplitude
such that the output falls by 10 dB. Pin 15
59
64
69
dB
47
Pin 31 detector output
AGC F.O.M.
Signal-to-noise ratio
S/N-AM
1 MHz, 74 dBµ, fm = 1 kHz, 30% modulation
Total harmonic distortion
THD-AM
1 MHz, 74 dBµ, fm = 1 kHz, 80% modulation
Signal meter output
Oscillator buffer output
Wide band AGC sensitivity
SD sensitivity
IF buffer output
dB
52
dB
0.3
1
%
V
VSM AM-1
No input
0.0
0.2
0.5
VSM AM-2
1 MHz, 130 dBµ, unmodulated
3.5
4.4
6.1
No input, the pin 15 output
185
230
VOSCBUFF AM1
V
mVrms
W-AGCsen1
1.4 MHz, the input when V46 = 0.7 V
92
98
104
dBµ
W-AGCsen2
1.4 MHz, the input when V46 = 0.7 V (seek mode)
83
89
95
dBµ
SD-sen1 AM
1 MHz, the ANT input level such that the IF counter output turns on.
24
30
36
dBµ
SD-sen2 AM
1 MHz, the ANT input level such that the SD pin goes to the on state.
24
30
36
1 MHz, 74 dBµ, unmodulated. The pin 23 output
200
290
VIFBUFF-AM
dBµ
mVrms
Note: These measurements must be made using the either the IC-51-0644-824 or KS8277 IC socket (manufactured by Yamaichi Electronics).
* 1. When the resistor between pin 58 and ground is 200 kΩ.
* 2. When the resistor between pin 58 and ground is 30 kΩ.
No. 6039-3/50
LA1784M
Function List
FM Front End (Equivalent to the Sanyo LA1193)
• Double input type double balanced mixer
• Pin diode drive AGC output
• MOSFET second gate drive AGC output
• Keyed AGC adjustment pin
• Differential IF amplifier
• Wide band AGC sensitivity setting pin, and narrow
band AGC sensitivity setting pin
• Local oscillator
FM IF
• IF limiter amplifier
• S-meter output (also used for AM) 6-stage pickup
• Multipath detection pin (shared FM signal meter)
• Quadrature detection
• AF preamplifier
• AGC output
• Band muting
• Weak input muting
• Soft muting adjustment pin
• Muting attenuation adjustment pin
• IF counter buffer output (also used for AM)
• SD (IF counter buffer on level) adjustment pin
• SD output (active high) (also used for AM)
Noise Canceller
• High-pass filter (first order)
• Delay circuit based low-pass filter (fourth order)
• Noise AGC
• Pilot signal compensation circuit
• Noise sensitivity setting pin
• Function for disabling the noise canceller in AM
mode
Multiplex Functions
• Adjustment-free VCO circuit
• Level follower type pilot canceller circuit
• HCC (high cut control)
• Automatic stereo/mono switching
• VCO oscillation stop function (AM mode)
• Forced monaural
• SNC (stereo noise controller)
• Stereo display pin
• Anti-birdie filter
AM
• Double balanced mixer (1st, 2nd)
• IF amplifier
• Detection
• RF AGC (narrow/wide)
• Pin diode drive pin
• IF AGC
• Signal meter output (also used for FM)
• Local oscillator circuits (first and second)
• Local oscillator buffer output
• IF counter buffer output (also used by the FM IF)
• SD (IF counter buffer on level) adjustment pin
• SD output (active high) (also used for AM)
• Wide AGC
• Detection output frequency characteristics
adjustment pin (low cut, high deemphasis)
• AM stereo buffer
MRC (multipath noise rejection circuit)
AM/FM switching output (linked to the FM VCC)
No. 6039-4/50
LA1784M
Operating Characteristics and Symbols Used in the Test Circuit Diagrams
Switches (SW)
Switch on = 1, SW off = 0
There are two switches that use signal transfer.
— SW2: switches between the mixer input and the IF input.
— SW4: switches between noise canceler input and IF output + noise canceler input.
Types of SG used
PG1 (AC1)
Used for noise canceler testing. A pulse generator and an AF oscillator are required.
AC2
Used for FM front end testing. Outputs an 83 MHz signal.
AC3
Used for FM IF, noise canceler, and MPX testing. Outputs a 10.7 MHz signal. Stereo modulation must be possible.
AC4
Used for AM testing. Outputs 1 MHz and 1.4 MHz signals.
AC5
Used with the MRC. Can also be used for AF and OSC.
Power supply
VCC
8V
VCC1
5V
VCC2
0.1 V / 0.7 V / 2 V / 4 V
VCC3
0.1 V / 0.6 V / 2 V
SD, stereo, seek/stop
These levels
must be variable.
Keyed AGC, Mute ATT
HCC, SNC, SASC (MRC)
• Switches
Parameter
ON
SW1
AM/FM switching. The FE VCC is supplied to pin 62.
SW2
FM IF switching. Pin 51/FE output
SW3
For conversion gain testing
SW4
For switching between noise canceler input and IF output + noise canceler.
SW5
High-speed SD
SW6
SEEK/STOP (IF BUFF ON/OFF)
SW7
SW8
SW9
For pilot cancellation testing
SW10
Mute off (pin 33)
OFF
FM
AM
FE IF OUT (A)
AC3 (B)
Conversion gain measurement (A)
Other/purposes
AC1 (A)
Other/purposes
High-speed SD
Other/purposes
STOP
Seek (IF buffer output)
MUTE ATT 200 kΩ
MUTE 200 kΩ
OFF
MUTE ATT 30 kΩ
MUTE 30 kΩ
OFF
When pilot cancellation is used
When pilot cancellation is not used
MUTE OFF
MUTE ON
• Trimmers (variable resistors)
VR1
Separation adjustment
VR2
Pilot cancellation adjustment
Test Points
• DC voltages
VD1
FM RF AGC voltage
Pin 2
VD2
AM/FM SD, AM Tweet, FM stereo indicator
Pin 26
VD3
AM/FM S-meter
Pin 24
VD4
MRC output
Pin 27
VD5
Mute drive output
Pin 33
VD6
AM antenna damping voltage
Pin 46
VD7
N.C. Gate time
Pin 8
• AC voltages
VA1
AM/FM OSC Buff
Pin 4
VA2
First IF output
Pin 53 → CF → pin 51 load level (10.7 MHz)
VA3
IF counter buffer
Pin 23 (10.7 MHz/450 kHz)
VA4
MPX OUT Left ch
Pin 15 (AF)
VA5
MPX OUT Right ch
Pin 16 (AF)
No. 6039-5/50
LA1784M
Pin Descriptions
Pin No.
Function
Description
Equivalent circuit
VCC
62 pin
ANT
RF
AGC
1000 pF
1
Antenna damping drive
An antenna damping current flows
when the RF AGC voltage (pin 2)
reaches VCC – VD.
300 Ω
100 Ω
1
100 Ω
1000 pF
A11711
VCC
FET
2ND GATE
2
RF AGC
+
Used to control the FET
second gate.
12 kΩ
2
ANT
N
AGC
DET
DAMPING
DRIVER
W
AGC
DET
VCC
KEYED
AGC
A11712
3
F.E.GND
VCC
4
OSC
Oscillator connection
The transistor and capacitors
required for the oscillator circuit.
4
25 pF
VT
2 kΩ
20 pF
A11713
7
VCC
7
AM OSC
AM first oscillator
This circuit can oscillator up to the
SW band.
An ALC circuit is included.
A L C
A11714
Continued on next page.
No. 6039-6/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
3 kΩ
15 kΩ
3 kΩ
8
9
Noise AGC sensitivity
AGC adjustment
After setting up the medium field
(about 50 dBµ) sensitivity with the
noise sensitivity setting pin (pin 8),
set the weak field (about 20 to
30 dBµ) sensitivity with the AGC
adjustment pin (pin 9)
200 Ω
8
9
3 kΩ
+
1 MΩ
0.01 µF
0.47 µF
A11715
A11715
0.01 µF
13
11
12
Memory circuit connection
6800 pF
12
3.9 kΩ
11
VCC
Recording circuit used during
noise canceller operation.
Differential
amp
Gate
circuit
LPF
A11716
VCC
30 kΩ
PLL
13
Pilot input
Pin 13 is the PLL circuit input pin.
N.C
12
13
0.01 µF
A11717
14
N.C, MPX, MRC, GND
Ground for the N.C., MPX, and
MRC circuits.
Continued on next page.
No. 6039-7/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
VCC
15
16
MPX output (left)
MPX output (right)
Deemphasis
50 µs: 0.015 µF
75 µs: 0.022 µF
3.3 kΩ
3.3 kΩ
15
16
0.015 µF
0.015 µF
A11718
VCC
20 kΩ
17
Pilot canceller signal output
Adjustment is required since the
pilot signal level varies with the
sample-to-sample variations in
the IF output level and other
parameters.
6.7 kΩ
10 kΩ
17
18
0.01 µF
100 kΩ
A11719
A11719
VCC
18
Pilot canceller signal output
Pin 18 is the output pin for the
pilot canceller signal.
1.5 kΩ
17
18
0.01 µF 100 kΩ
A11720
Continued on next page.
No. 6039-8/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
Composite
signal
19
Separation
adjustment pin
DECODER
5 kΩ
Use a trimmer to adjust the
subdecoder input level.
(The output level is not modified in
mono and main modes.)
19
30 kΩ
0.047 µF
A11721
CSB
912
JF108
20
VREF
20
VCO
The oscillator frequency is 912 Hz.
KBR-912F108
(Kyocera Corporation)
CSB-912JF108
(Murata Mfg. Co., Ltd.)
10 pF
A11722
VREF
15 kΩ
PHASE COMP.
PHASE COMP.
+
15 kΩ
19 kΩ
21
22
+
+
21
22
A11723
Continued on next page.
No. 6039-9/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
4.9 V
23
IF counter buffer seek/stop
switching
This pin functions both as the IF
counter buffer (AC output) and as
the seek/stop switch pin.
The voltage V23 switches
between the following three
modes.
During FM reception:
5 V: Seek mode
2.5 V: Forced SD mode
0 V: Reception mode
AM reception
(two modes: 0 and 5 V)
5 V: Seek mode
0 V: Reception mode
+
–
50 kΩ
+
–
AM MUTE
1.3 V
IF counter
buffer
VCC
10 kΩ
150 Ω
+
–
SW
50F
SD circuit
23
51 kΩ
STOP
IF
BUFF.
Forced
SEEK
SD: 2.5 V 5 V
A11724
VCC
FM
S-meter
24
32
AM/FM signal meter
Dedicated FM signal meter
Fixed-current drive signal meter
output
In AM mode, pin 32 outputs a
1-mA current. Thus the HCC
circuit is turned off.
32
10 kΩ
AM
S-meter
24
10 kΩ
AM/FM
SW
Outputs a 1-mA
current during AM
reception
AM/FM
SW
MRC
A11725
26
Stereo indicator for the SD pin
The voltage V23 switches
between three modes as follows.
FM reception:
5 V: The SD pin operates linked
to the IF counter buffer.
2.5 V: Forced SD mode: operates
as the SD pin.
0.7 V: Reception mode: stereo
indicator
AM reception: (two modes: 0 and 5 V)
5 V: Operates as the seek SD pin.
0 V: Reception mode. Not used.
AM/FM
SD
Stereo
indicator
Seek/stop
switching
26
100 kΩ
VDD
A11726
Continued on next page.
No. 6039-10/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
VCC
VCC
C2
27
MRC control voltage time
constant
+
2 µA
27
The MRC detector time constant
is determined by a 100 Ω resistor
and C2 when discharging and by
the 2-µA current and C2 when
charging.
100 Ω
Pin 28
A11727
VREF
28
SNC control input
The sub-output is controlled by a
0 to 1-V input.
28
A11728
VREF
The high band frequency output is
controlled by a 0 to 1-V input.
29
HCC control input
It can also be controlled by the
MRC output.
Use a resistor of at least 100 kΩ
when controlling with the pin 32
FM S-meter signal.
32
29
1 µF
+
A11729
Continued on next page.
No. 6039-11/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
VCC
FM
detector
output
30
31
Noise canceller input
Pin 30 is the noise canceller input.
The input impedance is 50 kΩ.
AM/FM detector output
Pin 31 is the AM and FM detector
output
In FM mode, this is a lowimpedance output.
In AM mode, the output
impedance is 10 kΩ.
To improve the low band
separation, use a coupling
capacitor of over 10 µF.
31
10 kΩ
VCC
1 µF
AM
detector
+
30
Noise
canceller
50 kΩ
4.2 V
A11730
VCC
32
32
IF S-meter output and MRC
DC input
FM S-meter output block
MRC AC input block
Adjust the external 1-kΩ resistor
to attenuate the MRC AC input
and control the circuit.
10 kΩ
+
1 µF
1 kΩ
MRC input
A11731
C1
+
•The muting time constant is
determined by an external RC
circuit as described below.
Attack time: TA = 10 kΩ × C1
Release time: TR = 50 kΩ × C1
33
Mute drive output
•Noise convergence adjustment
The noise convergence can be
adjusted when there is no input
signal by inserting a resistor
between pin 33 and ground.
•Muting off function
Ground pin 33 through a 4-kΩ
resistor.
0.1 µF
33
VCC
50 kΩ
MUTE
AMP.
SEEK
OFF
SOFT
MUTE
10 kΩ
HOLE
DET
Band
muting
50 kΩ
SD circuit
A11732
Continued on next page.
No. 6039-12/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
0.1 µF V
REF
R1
VCC
C
R2
37
36
35
34
VCC
•The resistor R1 determines the
width of the band muting function.
Increasing the value of R1
narrows the band.
Reducing the value of R1 widens
the band.
AGC
QD output
QD input
VREF
•Null voltage
When tuned, the voltage between
pins 34 and 37, V34 – 37, will be 0 V.
The band muting function turns
on when |V34 – 37| ≥ 0.7 V.
HOLE
DET
390 Ω
34
35
36
37
Quadrature
detector
3 pF
V37 = 4.9 V
1 kΩ
IF limitter amplifier
Band
muting
A11733
R
SD ADJ
38
38
FM SD ADJ
A 130-µA current flows from pin
38 and, in conjunction with the
external resistance R, determines
the comparison voltage.
130 µA
+
–
SD
Comparator
24
S-meter
A11734
24
S-meter
6.4 kΩ
3.6 kΩ
39
Keyed AGC
AM stereo buffer
The keyed AGC operates when
the voltage created by dividing the
pin 24 S-meter output voltage by
the 6.4 and 3.6 kΩ resistors
becomes lower than the voltage
determined by the resistor
between pin 39 and ground.
This pin also is used as the AM
stereo IF buffer pin.
Comparator
KEYED
AGC
+
–
1.3 V
90 µA
39
VCC
AM IF out
50 pF 150 Ω
A11735
Continued on next page.
No. 6039-13/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
VCC
20 kΩ
+
41
HCC capacitor
20 kΩ
The HCC frequency characteristics
are determined by the external
capacitor connected at this pin.
41
2200 pF
A11736
This pin is used to change the
frequency characteristics of the
unneeded audio band under
100 Hz in AM mode to produce
a clear audio signal.
VCC
C
42
42
AM L.C. pin
Note: The LC capacitor must be
connected between this pin
and VCC (pin 40).
This is because the detector
circuit operates referenced
to VCC.
VCC
DET
50 kΩ
1 kΩ
+
–
50 kΩ
The cutoff frequency fC is
determined by the following
formula.
1 kΩ
A11737
fC = 1/2π × 50 k × C
VCC
19 kHz∠0°
BIAS
30 kΩ
43
Pilot detector
Inserting a 1-MΩ resistor between
pin 43 and VCC will force the IC
to mono mode.
30 kΩ
+
30 kΩ
43
1 µF
+
A11738
Continued on next page.
No. 6039-14/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
VCC
C
2.2 µF
+
0.022 µF
240 kΩ
42
44
IF AGC
G1; Used for time constant
switching during seeks.
• Reception
τ = 2.2 µF × 300 kΩ
• Seek
τ = 2.2 µF × 10 Ω
The external capacitors are
connected to VCC.
This is because the IF amplifier
operates referenced to VCC.
44
VCC
DET
50 kΩ
50 kΩ
IF
AGC
G1
SEEK
ON
10 Ω
A11739
Pin 40 VCC
45
Pin 40 VCC
45
IF output
The IF amplifier load
DET
A11740
VCC
50 pF
46
100 Ω
46
AM antenna damping
drive output
Wide band AGC input
I46 = 6 mA (maximum)
This is the antenna damping
current.
20 kΩ
VCC
W.AGC AMP.
ANT DAMPING
DRIVER
A11741
Continued on next page.
No. 6039-15/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
30 kΩ
R
47
VCC
FM muting on level
adjustment
140 µA
+
–
47
Modify the value of the external
resistor to adjust the muting on
level.
Pin 24
Inverter
MUTE
A11742
VCC
5.6 V
48
57
RF AGC bypass
RF AGC
RF AGC rectification capacitor
The low frequency distortion is
determined as follows:
Increasing C48 and C57 improves
the distortion but makes the
response slower.
Reducing C48 and C57
aggravates the distortion but
makes the response faster.
10 kΩ
48
+
–
+
Antenna
damping
3.3 µF
For AGC use
57
+
47 µF
A11743
2.6 V
50
51
IF bypass
FM IF input
Due to the high gain of the limiter
amplifer, care must be taken when
choosing the grounding point for
the limiter amplifer input capacitor
to prevent oscillation.
10 kΩ
10 kΩ
50
0.022 µF
330 Ω
51
IF in
A11744
2 kΩ
100 Ω
52
IF input
The input impedance is 2 kΩ.
52
A11745
Continued on next page.
No. 6039-16/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
VCC
IF OUT 53
• Input and output pin or the first
IF amplifier
• Inverting amplifier
53
56
IF amplifier output
IF amplifier input
300 Ω
300 Ω
V56 = 2 V
Input impedance: RIN = 330 Ω
2.75 V
V53 = 5.3 V
Output impedance
ROUT = 330 Ω
IF IN 56
A11746
Pin 40 VCC
Pin 40 VCC
54
54
49
Mixer output: 130 µA
Mixer input
OSC
The mixer coil connected to the
pin 54 mixer output must be
wired to VCC (pin 40).
The pin 49 mixer input
impedance is 330 Ω
49
330 Ω
A11747
Pin 62
VCC
W-AGC
N-AGC
Pins 55 and 58 include built-in
DC cut capacitors.
The AGC on level is determined
by the values of the capacitors
C1 and C2.
55
W-AGC IN
AM SD ADJ
58
N-AGC IN
Muting attenuation
adjustment pin
Pin 55 functions as the SD
sensitivity adjustment pin in
AM mode.
The output current I55 is 50 µA,
and V55 varies depending on the
value of the external resistor.
The SD function operates by
comparing V55 with the S-meter
voltage.
55
30 pF
C1
MIX
IN
50 pF
58
C2
50 µA
MIX
OUT
+
–
AM SD
Signal meter
A11748
Continued on next page.
No. 6039-17/50
LA1784M
Continued from preceding page.
Pin No.
Function
Description
Equivalent circuit
1ST.IF
O S C
59
Double balanced mixer
Pins 59 and 60 are the mixer
10.7-MHz output
VCC
60
59
60
Mixer output
63
64
Mixer input
Pins 63 and 64 are the mixer
input.
This is an emitter insertion type
circuit, and the amount of
insertion is determined by the
capacitors C1 and C2.
30 Ω
VCC
C1
63
Note:The lines for pins 63 and 64
must be kept separated from
the lines for pins 59 and 60.
RF AMP
5 pF
C2
64
5 pF
620 Ω
620 Ω
A11749
Pin 6 functions both as the FM
front end VCC and the AM/FM
switching circuit.
6
Front end VCC AM/FM
switching
V6 voltage
Mode
When 8 V → FM
VCC
SD
510 Ω
6
+
–
+
FM.F.E
AGC 100 kΩ
8V
OPEN → AM
AM/FM
switching circuit
3.3 V
3
GND
A11750
AM 1st
MIX
to RF
Amp.
62
62
1st MIX
INPUT
10 kΩ
First mixer input
The input impedance is about
10 kΩ.
2.1 V
A11751
10 kΩ
5.6 V
10
AM 2nd OSC
Crystal oscillator circuit
The Kinseki, Ltd. HC-49/U-S and
a CL of 20 pF must be used.
20 pF
to 2nd
MIX
33 pF
10
X tal
A11752
No. 6039-18/50
LA1784M
Block Diagram
VCC
0.022µF
TO AM STEREO
(IF OUT)
40
39
0.47µF
38
37
ANT
D
49
36
220Ω
51
HOLE
DET
FMVSM
FM SD
AMVSM
AM SD
IF
AGC
DET
DC-C AFC
DET CLAMP
+
58
W.B.AGC
59
RF AGC
VCO
STOP
MAIN
HC
AMP
KEYED
AGC
VCC 30Ω
+
SEP.ADJ
FF
18
SUB MAT
DEC RIX
COUNTER
100kΩ
17
10
11
12
13
AM
OSC
6800pF 0.01µF
14
+
15
16
MPX
OUT
300pF
NC MPX GND
10µF
10µF
240kΩ
22kΩ
4.7kΩ
51kΩ
22kΩ
68pF
2.2kΩ
200kΩ
1kΩ
L
10µF
10µF
10kΩ
R
+
+
+
0.022µF
0.022µF
AM/FM OSC BUFF
18pF
+
10.26MHz
22kΩ
10pF
5pF
9
FMIF AM GND
30kΩ
+
8
0.015µF
7
0.015µF
6
0.47µF
5
18pF
0.01µF
1MΩ
4
FMIF AM NC MPX VCC
1µF
3
0.22µF
100kΩ
1µF
+
10kΩ
10µF
3SK583
19
18
17
16
15
VSS
PD
VDD
FM IN
AM IN
14
100pF
+B
12V
13
12
1.5kΩ
11
+
5.6V
22kΩ
20
100pF
100kΩ
0.22µF
22pF
100pF
100µF
100pF
51kΩ
7.2MHz
DO
5
6
7
8
9
FM/AM
10
1kΩ
+
9.1V
22kΩ
CL
4
100kΩ
CI
3
100µF
CE
2
10kΩ
1
10kΩ
LC7216M
22pF
1kΩ
0.01µF
+
100kΩ
19
30kΩ
2.2kΩ
*
CSB912JF108
or
KBR912F108
0.047µF 20kΩ
FF
38k<0
GATE
10kΩ
RF AGC
ANT D
2
FM GND
FM/AM VT
TRIG
GND
10kΩ
0.22µF
1µF
*
0.01µF
PI.CAN ADJ
1
100Ω
0.022µF
AGC
– +
ANT
D
FE GND
30kΩ
5pF
200kΩ
0.1µF
30kΩ
21
TRIG
P-CAN
AMP
PICAN
INPUT
0.022µF
18pF
64
100kΩ
180Ω 3SK263
BUFF
AM
1ST
OSC
63
5pF
OSC
0.022µF
GND
100kΩ
9pF
39pF
100kΩ
1000pF
NOISE
AMP
BUFF
1000pF
100kΩ 100F
0.022µF
22pF 22pF
+
PILOT
DET
LPF
20
AM/FM
SEEK→AM/FM SD
STOP→FM ST IND.
5V
5.6kΩ
22
+
HPF
8pF
1000pF
VCO
61
0.022µF
62
GND
AM/FM
S-METER 0.47µF
23
FF
19k<0
MIX
FEVCC
24
PHASE
COMP
INPUT
60
30Ω
FF
19k<90
k
FM/AM VSM
MUTE ATT
VCC
10kΩ
26
HCC
62pF
0.022µF
2kΩ
SNC
RIGHT CH.
330Ω
SEEK
SW
1µF
HCC
1µF
25
SD/ST
IND
8200pF AM HC
27
56
57
50kΩ AM LEVEL ADJ
NC-IN
SNC
IF AM/FM
REG
SW
TWEET
AM FM
VREF
200kΩ
28
+
+
RF AGC
WB AGC
55
FE IF IN
300Ω
29
MRC
MIX
FM WB AGCIN
20kΩ
METER
DET OUT
IF BUFF
54
1000pF
0.47µF
MUTE
DRIVE
L.C.
53
AM SD ADJ
AM MIX OUT
FM ANT IN
AFC IN
30
BUFF
52
1kΩ
100kΩ
FM
240kΩ
AM IF IN
31
MUTE
AMP
Q.DET
IF limiter
limiter
amplifier
amplifier
100Ω
510kΩ
32
LEFT CH.
15pF
15pF
47µF
100kΩ
+
0.022µF
OSC
OSC
BUFF
50
FM IF OUT
AM RF GND
MUTE DRIVE
1µF
33
34
22kΩ
FM IF IN
ANTD
0.022µF
AM ANT IN
35
N.C.MPX
GND
FC18
100µH
AM VCC
QD OUT
QD IN
VREF
0.22µF
100µF
41
100kΩ
42
GND
43
6.8kΩ KEYED AGC
30kΩΩ FM SD ADJ.
AM LC
2200pF
0.022µF
1µF
44
+
+
45
10kΩ
1µF
100µF
0.022µF
2.2µF
46
0.1µF
+
47
+
+
10kΩ
1MH
620Ω
30MH
+
240kΩ
RFAGC
48
0.022µF
+
CHCC
0.022µF
+
IF7
3.3µF
30Ω
11kΩ
PILOT DET
GND
100pF
CE
CI
CL
DO
RDS
ADC MUTE SD/MONO
ST
R ON
LC867148
A11753
No. 6039-19/50
LA1784M
AC Characteristics Test Circuit
VCC
8V
VCC
0.47µF
35
0.1µF
MUTE DRIVE
33
34
32
31
MUTE
AMP
Q.DET
AMVSM
AM SD
IF
AGC
DET
30
HOLE
DET
FMVSM
FM SD
MUTE
DRIVE
29
DC-C AFC
DET CIAMP
L.C.
28
MRC-IN
+
8200pF AM HC
NC-IN
PG1
(AC1)
HCC
HCC
SNC
1µF
SNC
58
W.B.AGC
59
RF AGC
HCC
FF
19<0
MAIN
HC
6
7
FF
18
SUB MA
DEC TRIX
SW1
+
100kΩ
VD3
100kΩ
VR2
0.01µF
PI.CAN ADJ
8V
0.022µF
3pF
VCC2
VA8
15
16
MPX
OUT
0.015µF
14
SEP.ADJ VR1
SW9
8V
0.022µF
3pF
VCC
10µF
10µF
8V
VA1
SW10
10.26MHz
X TAL
VCC
10
11
12
13
AM
OSC
+
6800pF 0.01µF
+
0.022µF
FM VCC
FM GND
SW6
VA6
VA9
RIGHT CH.
20pF
20kΩ
9
0.01µF 10kΩ
1MΩ
OSC
0.022µF
VT
8
10kΩ
5
0.47µF
4
5pF
+
SW5
19
GATE
1MΩ
GND
TRIG
+
100Ω
0.022µF
AGC
10kΩ
1µF
100Ω
FE GND
ANT D
RF AGC
VD1
3
50kΩ
0.22µF
1µF
CSB912JF108
0.047µF 20kΩ
17
2
5V
VCC1
VA3
FM/AM IFBUFF.
5.6kΩ
20
FF
38k<0
ANT
D
1
50kΩ
+
21
TRIG
P-CAN
BUFF
AM
1ST
OSC
30kΩ
39pF
64
AM/FM
S-METER 0.47µF
+
PILOT
DET
63
5pF
22
BUFF
3pF
5pF
VCO
VCO
STOP
FF FM/AM
REG
SW
VD2
GND
SEEK→AM/FM SD
STOP→AM ST BUFFER
FM ST IND.
23
MIX
61
AM/FM
100kΩ
50Ω
+
1000µF
24
PHASE
COMP
– +
62
25Ω
LPF
FF
19<90
k
0.015µF
FEVCC
VCC
AC1
SG1
HPF
KEYED
AGC
0.022µF
VCC
50Ω
AM FM
VREF
60
SW7
VCC3
+
57
AM/FM OSC BUFF
200kΩ
25
0.022µF
30Ω
300kΩ
VD6
26
56
10pF
MUTE ATT
1kΩ
MRC
TWEET
300pF
ANTD
0.022µF
RF AGC
W.B. AGC
LEFT CH.
510Ω
SNC
VD4
+
MIX
55
N.C.MPX GND
FE IF IN
330Ω
JIS
DUMMY
SW8
27
10kΩ
20kΩ
+
0.022µF
47µF
100kΩ
6.8MH
FM WB AGCIN
0.022µF
15pF
65pF
30kΩ
+
AC2
SG2
100µH
AC5
SW4 (T)
A
B
NC-IN
IF BUFF
AM SD ADJ
AM MIX OUT
FC18
50Ω 30Ω
AM LEVEL ADJ
DET OUT
100µH
54
VCC2
1µF
FM S-METER
+
QD IN
AFC IN
QD OUT
0.22µF
100µF
VREF
36
BUFF
52
53
FM IF OUT
37
10kΩ
1MH
38
1MΩ
0.022µF
AM IF IN
39
IF limiter
amplifier
51
0.022µF
40
OSC
OSC
BUFF
330Ω
300Ω
200Ω
30Ω
41
4.3kΩ
VD5
+
+
42
10kΩ
+
43
6.8kΩ KEYED AGC
22kΩ FM SD ADJ.
AM LC
CHCC
2200pF
0.022µF
1µF
44
0.1µF
100kΩ
ANT
D
FM IF
IN
50
45
+
100kΩ
46
+
10kΩ
1µF
47
49
0.022µF
+
240kΩ
RFAGC
48
620Ω
+
IF7
+
2.2µF
3.3µF
B
SW2 ( i )
MIX A
50Ω
AC3
SG3
SW3
15kΩ
IF OUT
IF IN
300Ω
+
50Ω
MUTE OR ADJ
0.022µF
VA2
PILOT DET
GND
VA7
A11754
No. 6039-20/50
LA1784M
Test Conditions
Parameter
Current drain
Demodulation output
Pin 31 demodulation output
Channel balance
Total harmonic distortion (FM)
Symbol
Switch states
SW1
SW2
SW3
SW4
SW5
SW6
SW7
SW8
SW9
SW10
ICCO-FM
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
VO-FM
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
VO-FM31
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
CB
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
THD-FMmono
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
—
Signal-to-noise ratio: IF
S/N-FM IF
ON
b
OFF
b
—
ON
OFF
OFF
ON
AM suppression ratio: IF
AMR IF
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
Att-1
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
—
Muting attenuation
Separation
Att-2
ON
b
OFF
b
—
ON
OFF
OFF
ON
Att-3
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
Separation
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
Stereo on level
ST-ON
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
Stereo off level
ST-OFF
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
THD-Main L
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
PCAN
ON
b
OFF
b
—
ON
OFF
OFF
OFF/ON
—
Main total harmonic distortion
Pilot cancellation
AttSNC
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
HCC output attenuation 1
SNC output attenuation
AttHCC-1
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
HCC output attenuation 2
AttHCC-2
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
Vi-lim
ON
b
OFF
b
—
ON
OFF
OFF
ON
ON
Input limiting voltage
Muting sensitivity
Vi-mute
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
SD sensitivity 1
SD-sen1 FM
ON
b
OFF
b
OFF
OFF
OFF
OFF
ON
—
SD sensitivity 2
SD-sen2 FM
ON
b
OFF
b
ON
OFF
OFF
OFF
ON
—
VIFBUFF-FM
ON
b
OFF
b
OFF
OFF
OFF
OFF
ON
—
VSM FM-1
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
VSM FM-2
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
VSM FM-3
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
VSM FM-4
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
Muting bandwidth
BW-mute
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
Mute drive output
VMUTE-100
ON
b
OFF
b
—
ON
OFF
OFF
ON
—
N-AGC on input
VNAGC
ON
a
ON
b
—
ON
OFF
OFF
—
—
W-AGC on input
VWAGC
ON
a
ON
b
—
ON
OFF
OFF
—
—
Conversion gain
A.V
ON
a
ON
b
—
ON
OFF
OFF
—
—
VOSCBUFFFM
ON
a
ON
b
—
ON
OFF
OFF
—
—
τGATE1
ON
—
OFF
a
—
ON
OFF
OFF
—
—
SN
ON
—
OFF
a
—
ON
OFF
OFF
—
—
SN-NC
ON/OFF
—
OFF
a
—
ON
OFF
OFF
—
—
VMRC
ON
—
OFF
b
—
ON
OFF
OFF
—
—
—
IF counter buffer output
Signal meter output (FM)
Oscillator buffer output
Gate time 1
Noise sensitivity
NC effect
MRC output
MRC operating level
MRC-ON
ON
—
OFF
b
—
ON
OFF
OFF
—
Practical sensitivity
S/N-30
OFF
—
OFF
b
ON
ON
—
—
—
—
Detection output
VO-AM
OFF
—
OFF
b
ON
ON
—
—
—
—
Pin 31 detection output
VO-AM31
OFF
—
OFF
b
ON
ON
—
—
—
—
AGC F.O.M.
VAGC-FOM
OFF
—
OFF
b
ON
ON
—
—
—
—
Signal-to-noise ratio
S/N-AM
OFF
—
OFF
b
ON
ON
—
—
—
—
Total harmonic distortion (AM)
THD-AM
OFF
—
OFF
b
ON
ON
—
—
—
—
VSM AM-1
OFF
—
OFF
b
ON
ON
—
—
—
—
VSM AM-2
OFF
—
OFF
b
ON
ON
—
—
—
—
VOSCBUFF AM-1
OFF
—
OFF
b
ON
ON
—
—
—
—
W-AGCsen 1
OFF
—
OFF
b
ON
ON
—
—
—
—
W-AGCsen 2
OFF
—
OFF
b
ON
ON
—
—
—
—
SD-sen1 AM
OFF
—
OFF
b
OFF
OFF
—
—
—
—
SD-sen2 AM
OFF
—
OFF
b
OFF
OFF
—
—
—
—
VIFBUFF-AM
OFF
—
OFF
b
OFF
OFF
—
—
—
—
Signal meter output (AM)
Oscillator buffer output
Wide band AGC sensitivity
SD sensitivity
IF buffer output
No. 6039-21/50
LA1784M
Usage Notes
1. Notes on VCC and Ground
Pin 40
VCC for the FM IF, AM, NC, MPX, and MRC blocks
Pin 25
Ground for the FM IF and AM blocks
Pin 14
Ground for the NC, MPX, and MRC blocks
Pin 61
VCC for the FM front end, AM first mixer, and first oscillator blocks
* Pin 6
VCC for the FM front end and AGC blocks, and the AM/FM switching pin
Pin 3
Ground for the FM front end, first mixer, and first oscillator blocks
2. Notes on AM Coil Connection
The VCC used for the first oscillator coil connected to pin 7 must be at the same potential as pin 61.
Connect to the IFT connected with pin 45, and to the MIX coil connected with pin 54. VCC must be at the same potential
as pin 40.
3. AM/FM Switching
Pin 6 is also used as the FM front end and RF AGC VCC
Pin 6 voltage
Mode
8
FM
OPEN
AM
Fig. 1
4. Notes on the FM Front End
Notes on interference rejection characteristics
• Intermodulation characteristics
The LA1784M applies two high-band AGC functions to prevent IM (the generation of intermodulation). These are
the narrow AGC (pin 58: mixer input detection type) and the wide AGC (for the pin 55 input), and this results in the
antenna frequency characteristics shown in figure 2. The levels at which the AGC functions turn on are determined
by the capacitors attached at pins 55 and 58.
∆f — AGC Sensitivity
When ∆f = 0, 98.1 MHz
AGC sensitivity — dBµ
110
100
The wide AGC
sensitivity when
pin 39 is 5 V.
90
80
70
The narrow AGC
sensitivity when
pin 39 is at ground.
60
50
–5
–4
–3
–2
–1
0
1
2
3
4
5
∆f — MHz
Fig. 2
No. 6039-22/50
LA1784M
• Notes on second-channel attenuation suppression
Keyed AGC (3D AGC) is a technique for achieving good characteristics for both intermodulation and secondchannel attenuation at the same time. When the desired signal is faint or nonexistent, the high-band AGC level will
be essentially 0, and as a result automatic tuning may malfunction and blocking oscillation may occur in the
presence of strong interfering stations. Keyed AGC helps resolve these problems.
This 3D AGC technique uses information that has the following three frequency characteristics and is a unique
Sanyo-developed system for determining the high-band AGC level.
RF and ANT circuit information: Mixer input AGC
Mixer circuit information: Mixer output AGC
CF selectivity information: S-meter output
• 3D AGC Features
Feature
Merit
Only the narrow AGC sensitivity (operation at ∆f < 1.5 MHz) is
controlled by the field strength of the desired station.
• Effective in resolving second-channel attenuation problems.
The narrow AGC sensitivity is controlled by a voltage (V 23) that is
under 0.5 V.
• Allows effective resolution of second-channel attenuation problems without
degrading three-signal characteristics.
The wide AGC can operate even when V23 = 0 (when the desired
station is not present).
• Seek operations may stop incorrectly due to the occurrence of
intermodulation.
• It is possible to prevent the occurrence of intermodulation in the RF tuning
circuit and antenna in the presence of strong interfering stations, and
blocking oscillation due to AGC operation can be prevented.
The narrow and wide AGC sensitivities can be set independently.
(See figure 3 and 4.)
• Settings can be optimized for the field conditions.
The system has two AGC systems: narrow and wide AGC.
(See figure 5.)
• Since the narrow AGC operates for the desired station and adjacent
stations, the wide AGC sensitivity can be lowered and AGC malfunction
due to local oscillator signal can be prevented.
∆f — AGC on Level (ANT input)
∆f — AGC on Level (ANT input) Fig.4
Fig.3
Pin 55 capacitor: 3 pF
110
Wide AGC on level — dBµ
Narrow AGC on level — dBµ
110
100
90
Pin 58 capacitor:
10 pF
80
70
keyed AGC
39
Pin 58 capacitor:
47 pF
60
50
–5
–3
–4
–2
–1
1
0
2
3
4
90
Pin 55 capacitor: 10 pF
80
70
keyed AGC
39
5V
60
50
5
–5
–4
–3
–2
–1
0
1
2
3
4
5
∆f — MHz
∆f — MHz
Pin 59 narrow AGC and pin 55 wide AGC input levels — dBµ
100
W-AGC, N-AGC — f
Fig.5
70
80
s
Wide AGC on level frequency characteristic
Narrow AGC on
90
level frequency
characteristics
100
110
120
130
AGC input level frequency
characteristics such that
VRFAGC (pin 2) falls under 2 V.
140
7 1.0
2
3
5
7 10
2
3
5
7 100
2
3
5
Frequency, f — MHz
No. 6039-23/50
LA1784M
3D AGC Sensitivity Characteristics
AGC sensitivity
Wide AGC sensitivity
∆F
1
2
Second-channel
attenuation improvement
Narrow AGC sensitivity
3
Desired station AGC sensitivity
4
V23 (Desired station field strength)
A12075
Fig. 6
Figure 6 3D AGC Sensitivity — ∆f, V23 characteristics
• The wide AGC sensitivity is determined by the antenna and RF circuit selectivity, regardless of V23.
• The narrow AGC sensitivity is determined by the following.
The total selectivity of the antenna, RF circuit, and mixer when V23 ≥ 0.5 V
The above selectivity and V23 when V23 < 0.5 V
• The improvement in the second-channel attenuation corresponds to the area occupied by the narrow AGC in the
total AGC sensitivity area.
Figure 8 on the next page shows the actual operation of the circuit.
The fu input level at which antenna damping turns on — dBµ
∆f — AGC on Level (ANT input)
110
fD = 98.1 MHz Second-channel pad
100
90
ANT IN
VIN
80
70
fu = 98.1 MHz + ∆f
60
50
–5
–4
–3
–2
–1
0
1
∆f — MHz
2
3
4
A12076
5
Fig. 7
No. 6039-24/50
LA1784M
7. Notes on 3D AGC (Keyed AGC)
VCC
55
W-AGC
DET
58
N-AGC
DET
90µA
S-meter
+
–
VCC
+
–
1
2
39
24
+
ANT
DUMPING
VS-meter
A11763
Fig. 8
• The antenna damping current from the pin due to the pin diode flows when the V2 pin reaches the VCC - VBE
level.
• The narrow AGC operates as follows.
When pin V39 > pin V24: The narrow AGC turns off.
When pin V39 < pin V24: The narrow AGC turns on.
No. 6039-25/50
LA1784M
• The LA1784M includes two AGC circuits in its front end block.
— Antenna input limiter using a pin diode.
— FET second gate control
The AGC input pin is pin 59, and the AGC circuit turns on when a signal of about 30 mVrms is input.
AGC activation
The pin diode drive circuit turns on when VCC – V2 is greater than or equal to about 1 V, and input limitation is
applied to the antenna circuit. In application circuits, there will be an attenuation of about 30 to 40 dB. Next, when
an adequate current flows in the antenna attenuator pin diode, the inductance falls, the FET second gate voltage
drops, the FET gm falls, and the AGC operates. The recommended FET is the Sanyo 3SK263, which is an
enhancement-type MOSFET. Therefore, full AGC is applied when the voltage, VG2-S, between the second gate and
the source is 0. Note that if a depletion-type MOSFET is used, AGC will not be applied unless VG2-S is less than 0.
V2 AGC Characteristics
Fig.9
9
fr = 98.0 Hz
VCC = 8 V
Ta = 25°C
8
6
Range where AGC level AGC level due
the AGC does due to the
to the MOSFET
not operate
pin diode:
second gate:
about 35 dB
about 35 dB
5
4
3
2
1
0
–10
0
10 20 30 40 50 60 70 80 90 100 110 120 130 140
ANT IN — dBµ
63
62
MIX VCC
60
MIX INPUT
Due to optimized device geometry, emitter current, the bias, this IC
achieves the following performance.
59
MIX OUT
64
MIX OUT
• Mixer
The mixer circuit in this IC is a double-balanced mixer with both
balanced input and balanced output.
Input circuit type
Emitter input
Input impedance: 25 Ω
MIX INPUT
V2AGC — V
7
MIX
Mixer input usable sensitivity: 15 dBµ
Mixer input IMQS: 90.5 dBµ
(For an oscillator level of 200 mVrms)
OSC
* The mixer input IMQS is defined as:
fr = 98.8 MHz, no input
fu1 = 98.8 MHz, 1 kHz, 30% modulation
fu2 = 99.6 MHz, no modulation
The interference 1 and 2
input levels such that
generated intermodulation
output signal-to-noise ratio
becomes 30 dB when an
interference signal with the
same level as the mixer input
is input, and distortion occurs
in the mixer.
Mixer circuit
A12077
Fig. 10
No. 6039-26/50
LA1784M
• Oscillator
Figure 11 shows the type of oscillator circuit used in this IC. It includes both an oscillator and an oscillator buffer.
VCC
18pF
4
25pF
AM/FM
OSC BUFFER OUT
5
VT
20pF
A12078
Fig. 11
• Figure 12 shows the type of FM first IF amplifier used in this IC. It is a differential single-stage amplifier.
330Ω
TO MIX
FM IF input
56
53
330Ω
+
330Ω
–
A12079
Fig. 12
Specifications
Input impedance: 330 Ω
Output impedance: 330 Ω
Gain: 20 dB
No. 6039-27/50
LA1784M
5. FM IF
• Notes on the FM SD and SD adjustment
The figure below presents an overview of the FM SD and the IF count buffer.
4.9V
R
+
–
R
+
–
R
Band
muting
Muting
drive
output
HOLE
CLET
STEREO
IND
S-meter
IF count buffer
+
–
39
24
FM IF
33
23
26
5V
IF count output
SD
STEREO/MONO
2.5V 5V
Fig. 13
A11759
Figure 14 shows the relationship between the FM SD, the IF count buffer output, the S-meter, and the muting drive
output.
V24
Larger
values
of R33
S-meter
V38
V33
Smaller values of R33
V33
over 0.7 V
V33
over 0.7 V
V26
5V
SD
ON
On as an
SD signal
SD
ON
Mono
Stereo
V23AC
0.7 V
OFF
IF count
buffer
OFF
IF counter output off
V23DC
5V
2.5 V
0V
RDS and other types of SD detection can be used by switching these modes.
New LA1784M functionality:
For stereo input (when the V26 pin voltage is 0.7 V),
when this pin is shorted to ground (0.1 V or lower)
the IC will operate in forced mono mode.
A11758
Fig. 14
No. 6039-28/50
LA1784M
• Transient response characteristics during automatic tuning
The transient characteristics for SD and IF count buffer on/off operation are determined by the time constants of
the RC circuits attached to the following pins.
(1) Muting time constant: pin 33
(2) S-meter time constant: pin 24
(3) AFC time constant: pin 34
There are two points that require consideration when using fast tuning.
(1) The SD time constant due to the S-meter time constant
Since the current I24 (pin 24) varies with the field strength, the time constant also changes. There is no hysteresis
in the comparator.
If C24 is made smaller and the pin 24 voltage is used for the keyed AGC pin 23, C23 must be chosen so that
AGC during keyed AGC operation does not become unstable.
S-meter
SD comparator
I24
24
R24
C24
A12080
Fig. 15
(2) The SD time constant due to the pin 33 muting voltage time constant
The changes in volume due to field fluctuation during weak field reception can be made smoother by setting the
attack and release times during soft muting operation.
Mute
drive
Mute
amp
10kΩ
Muting time constants
Attack: 10 kΩ × C33
50kΩ
Attack
Release: 50 kΩ × C33
Release
33
C33
A11766
Fig. 16
Antenna input such that pin 5 goes high — dBµ
SD Sensitivity Adjustment
Fig.17
50
40
30
20
10
0
6
10
14
18
22
26
30
34
Resistance between the pin and ground — kΩ
No. 6039-29/50
LA1784M
However, when testing this stop sensitivity, note that when checking the waveform on the IF count buffer output
(pin 23), there are cases, such as that shown below, where current in the test system may be seen as flowing to
ground and cause oscillation that causes the IF count buffer output to go to the output state.
F.E.
IF buffer
amp
IF
5V
0.022 µF
Test system capacitance
The 10.7 MHz feeds back through ground.
A12081
Fig. 18
• FM Muting control pin (pin 47) (R47: 30 kΩ variable resistor)
The –3 dB limiting sensitivity can be adjusted with R47.
FM Soft Muting (1)
R47 = 7.5 kΩ
Fig.19
DET out
Output,
Output noise — dB
15 kΩ
10 kΩ
20 kΩ
Noise
Antenna input — dBµ
• FM muting attenuation adjustment (pin 58)
The muting attenuation can be switched between the three levels of –20, –30, and –40 dB by the resistor inserted
between pin 58 and ground. (Note that the exact values depend on the total tuner gain.)
The noise convergence with no input is determined by the pin 58 voltage.
58
100Ω
R58
R58
A11764
Mute ATT
Open
–20 dB
200 kΩ
–30 dB
30 kΩ
–40 dB
The attenuation can be set by making R33 smaller as listed
in the table above.
33
R33
A11765
Fig. 20
No. 6039-30/50
LA1784M
FM Soft Muting (2)
FM Soft Muting (3)
Fig.21
Fig.22
R47 = 7.5 kΩ
R47 = 7.5 kΩ
DET out
DET out
10 kΩ
Output,
noise —
Output noise
— dB
dB
Output — dB
10 kΩ
Output — dB
15 kΩ
200 kΩ
20 kΩ
Noi
se
15 kΩ
30 kΩ
Nois
2 0kΩ
Antenna input — dBµ
e
Antenna input — dBµ
VCC
Quadrature detector
200 kΩ
R
Mute amp.
(VCA)
+
–
R
+
–
N-AGC
Mute
drive
Limiter
R
58
33
31
DET out
To MIX out
Open
200 kΩ
30 kΩ
Fig. 23
A11767
• FM muting off function
Forcing this pin to the ground level turns muting off.
Detector
output 0
1
When the pin is at the ground level, the noise convergence will
be 10 dB and the –3 dB limiting sensitivity will be about 0 dBµ.
20
Antenna input
A12082
Fig. 24
No. 6039-31/50
LA1784M
• Hall detection
The Hall detection function detects the level of the pin 36 quadrature input signal and then applies peak detection
to that result. The result is output from pin 33. This circuit has three effects.
(1) It assures that muting will be applied for weak inputs with an antenna input of under 5 dBµ. The amount of
attenuation is referenced to an antenna input of 60 dBµ, fm = 1 kHz, and a 22.5 kHz dev output, and is variable
from 10 dB to 40 dB when there is no input. Thus one feature of this circuit is that the weak input noise
attenuation and the –3 dB limiting sensitivity for over 5 dBµ inputs can be set independently.
Hall Detection Output — Antenna Input Characteristics Fig.25
5
Area muted by Hall detection
V38pin — V
4
3
2
1
0
–20
–10
0
10
20
30
Antenna input — dBµ
(2) When the pin 36 quadrature input is a saturated input, the pin 36 noise level (Va) is detected and a peak-hold
function is applied to pin 33 (Vb) for locations rapid field strength variations and severe multipath occurs for
fields that result in an antenna input level of over 5 dBµ.
36
33
Vb
Va
0
+
0.1µF
0
A12083
Fig. 26
(3) Unique features
One unique feature of the LA1784M is that if there are adjacent stations such that f1 = 98.1 MHz and f2 =
97.9 MHz, a search operation will not stop at 98.0 MHz. Since VAFC = 0 V and VSM = 3.6 V at 98.0 MHz in
the situations shown in figure 27 and 28, even though Hall detection would normally not operate and SD would
be high, in this IC the Hall detection circuit will operate, VMute will be set to 1.2 V (over 0.7 V) and the SD
signal will go low, thus preventing incorrect stopping of the search.
No. 6039-32/50
Fig.27
f1
f2
ANT
IN
0
Pin 24, VSM — V
–1
6
4
2
0
6
4
2
f2 = 97.9 MHz, 120 dBµ
fm = 400 Hz, 22.5 kHz dev.
f1 = 98.1 MHz, 120 dBµ
fm = 1 kHz, 22. 5kHz dev.
0
8
Pin 26 (SD) — V
Unique Features of the LA1784M Hall Detection Circuit (2)
2
1
Fig.28
When the tuner is moved in 50 kHz steps.
With a 51 kΩ resistor between pins 37 and 34.
With the SD sensitivity adjusted to be 20 dBµ.
0
–1
6
4
2
0
97.7
97.9
97.8
98.0
98.1
98.2
Pin 24, VSM — V
1
When the tuner is moved in 50 kHz steps.
With a 51 kΩ resistor between pins 37 and 34.
With the SD sensitivity adjusted to be 20 dBµ.
Voltage between pins 37 and 34, VAFC — V
Pin 33, VMute — V
Unique Features of the LA1784M Hall Detection Circuit (1)
2
6
4
2
0
6
4
2
0
f2 = 97.9 MHz, 40 dBµ
fm = 400 Hz, 22.5 kHz dev.
f1 = 98.1 MHz, 40 dBµ
fm = 1 kHz, 22.5 kHz dev.
8
Pin 26 (SD) — V
Voltage between pins 37 and 34, VAFC — V
Pin 33, VMute — V
LA1784M
6
4
2
0
97.7
98.3
Frequency, fr — MHz
97.8
97.9
98.0
98.1
98.2
98.3
Frequency, fr — MHz
• Notes on the quadrature input level
When a strong field is being received the quadrature signal input (pin 36) requires a 200 mV rms input, and the
detection transformer and the damping resistor between pins 36 and 37 must be designed.
(We recommend the Sumida SA-208 transformer and a 10 kΩ resistor between pins 36 and 37.)
When the pin 36 input level falls below 160 mV rms, the Hall detection circuit operates and the pin 33 mute drive
output voltage increases. Therefore, when pin 36 input is from 160 to under 200 mV rms during strong field
reception, the muting circuit may or may not operate due to sample-to-sample variations between individual ICs.
Furthermore, the SD function may not operate, and the audio output level may be reduced. Incorrect operation due
to sample-to-sample variations and temperature characteristics can be prevented by keeping the pin 36 voltage at
200 mVrms or higher.
Pin 33 VMute — QD Input Level
SA208 + LA1784M IF Input Characteristics
Fig.29
6
Fig.30
4 0.8
With pins 34 and 37 shorted.
With 5 V applied to pin 24.
3 0.6
5
THD — %
Vmute — V
2 0.4
4
3
2
75 Ω
SG
75 Ω
+
0.022 µF
1
36
10.7 MHz
0
92
94
96
37
98
102
–100 –80 –60 –40 –20
–120
With the resistor between
pins 36 and 37 open.
With a 10 kΩ resistor
between pins 36 and 37.
0
20
–0.2
–0.4
40
60
80
∆f — kHz
100 120
∆f=0→
10.7 MHz
–0.6 Voltage between pins 37 and 34
LA1888M
100
THD 1 kHz
75 kHz dev
1 0.2
–0.8 (referenced to the pin 37 voltage)
104
106
QD input level — dBµ
No. 6039-33/50
LA1784M
R36-37
Detector output Pin 36 AC level
MPX OUT
Vo
QDIN
Open
330 mVrms
235 mVrms
10 kΩ
280 mVrms
200 mVrms
• Band Muting Adjustment Procedure
The muting bandwidth can be modified as shown in figure 31 with the resistor RBW between pin 34 and 37.
Bandwidth such that the pin 33 voltage ≥ 2 V — kHz
RBW — Muting Bandwidth
Fig.31
280
RBW
+
240
+
1 µF
0.47 µF
SA208
Sumida
200
10 kΩ
37
160
36
35
34
ANT IN 98 MHz 100 dBµ
120
80
40
0
1.0
3
2
5
7
2
10
3
5
7 100
2
Resistor RBW between pins 34 and 37 — kΩ
6. AM
• AM AGC system
The LA1784M RF AGC circuit takes its input from three sources: the WIDE AGC pin (pin 46), the MIDDLE
AGC pin (pin 49) and NARROW AGC. There is also an IF AGC circuit.
RW
1st MIX 10.7MHz CF
62
RF
2nd MIX 450kHz CF
49
IF Amp.
DET
52
31
VCC
42
1st OSC
X'tal
240 kΩ
VCC
Amp.
46
IF AGC
44
2.2 µF
Middle AGC IN
Narrow AGC IN
Wide AGC IN
ANT
damping
RF AGC
57
+
47 µF
48
+
3.3 µF
Fig. 32
A11762
No. 6039-34/50
LA1784M
AM AGC f characteristics
Wide AGC
Operates for wide
band interference
Wide AGC
Operates for
wide band
interference
AGC on level
90
Middle AGC
Operates for
interference within
±70 kHz of the
received frequency.
80
70
Middle AGC
Operates for
interference within
±70 kHz of the
received frequency.
Narrow AGC
Operates at the
received frequency.
60
1000
900
800
Fig.33
100
1100
1200
Frequency — Hz
Wide Band AGC Circuit
Fig.34
30 Ω
110
50 Ω
–6dB
50 Ω
SG
Received frequency:
1 MHz
0.022 µF
46
0.022 µF
100
510 Ω
ANTD
0.022 µF
90
80
70
1.0
2
3
5
7
10
2
3
5
Pin 46 input — MHz
The wide band AGC circuit in this IC has the frequency characteristics shown above. The pin 46 input frequency
characteristics are identical to those of the RF amplifier gate. This AGC circuit serves to prevent distortion at the
FET input when a strong signal is applied to the antenna circuit. The level at which the AGC circuit turns on can be
adjusted to an arbitrary level with the wide band AGC adjustment resistor. A delayed AGC on level can be handled
by reducing the value of the adjustment resistor.
Wide band AGC adjustment resistor
0.022 µF
VCC
30 Ω
620 Ω
1MH
100 µH
FC18
57
15 pF
15 pF
+
47 µF
100 kΩ
0.022 µF
100 µH
30MH
Antenna damping on input level — dBµ
120
62
Fig. 35
A12084
No. 6039-35/50
LA1784M
• Notes on AM SD (pin 26) and the SD adjustment pin
SD and the IF buffer are operated by comparing the S-meter level (V24) and the 5 V reference voltage as shown in
figure 36.
S-meter
AM IF
Comparator
VCC
+
–
IF buff amp.
50 pF
50 µA
55
24
23
26
100 kΩ
100 kΩ
0.47 µF
0.022 µF
51 kΩ
IF buffer
5V
SD
Seek
5V
Fig. 36
A12085
Figure 37 shows the relationship between the AM SD, the IF count buffer, and the S-meter.
V24PIN
Larger
values
of R55
S-meter
V55
V26
Smaller values of R55
SD on
V23AC
IF buffer on
OFF
V23DC
5V
Pin 55: AM SD adjustment pin
0V
A11760
Antenna input such that pin 26 becomes 5 V — dBµ
AM SD Sensitivity Adjustment
Fig.38
80
70
60
50
40
30
20
10
0
0
10
20
30
40
50
Resistance between pin 55 and ground — kΩ
No. 6039-36/50
LA1784M
• AM high band cut and detector output level adjustment methods
The pin 31 AM and FM tuner output has an impedance of 10 kΩ in AM mode and a few tens of Ohms in FM
mode. Therefore, R31 is used to lower the AM detector output level and C31 determines the AM high band
frequency characteristics.
VCC
FM
detector
31
R31
C31
VCC
+
AM
detector
10 kΩ
Noise
canceler
input
30
50 kΩ
A12086
Fig. 39
• AM stereo system pins
To the AM stereo decoder
VCC
GND
400 mV rms
450 kHz output
IFT
45
39
VCC
50 pF 150 Ω
Keyed AGC
IF AMP.
Fig. 40
A11761
No. 6039-37/50
LA1784M
• AM low band cut adjustment method
The AM low band frequency characteristics can be adjusted with C42, which is inserted between pin 42 and VCC.
Since the detector is designed with VCC as the reference, C42 must be connected to VCC.
Detector Output — Frequency
Fig.42
20
0.1 µF
VCC
80%mod
With no
C31 used.
10
42
50 kΩ
10 kΩ
+
AM
detector
10 kΩ
–
50 kΩ
To pin 31
10 kΩ
Detector output — dB
C42
0
30%mod
0.022 µF
C31pin
0.047 µF
= 6800 pF
0.1 µF
C42pin= Using SEP 450H
–10
–20
–30
A12087
Fig. 41
–40
fr = 100 kHz
fm = 10 kHz 30%mod
–50
3
5 70.01
2 3
5 7 0.1
2 3
5 7 1.0
2 3
5 7 10
2
Frequency — Hz
7. Noise Canceler Block
• The noise canceler input (pin 30) has an input impedance of about 50 kΩ. Check the low band frequency
characteristics carefully when determining the value of the coupling capacitor used. Note that fC will be about 3 Hz
when a 1 µF capacitor is used in the application.
• Pins 8 and 9 are used to set the noise detector sensitivity and the noise AGC. It is advisable to first set the noise
sensitivity for a medium field (an antenna input of about 50 dBµ) with pin 8 (the noise sensitivity setting pin), and
then set the AGC level for a weak field (20 to 30 dBµ) with pin 9 (the AGC adjustment pin). If the noise sensitivity
is increased, the AGC will become more effective but, inversely, the weak field sensitivity will be reduced.
Noise canceler 10 kHz overmodulation malfunction may be a problem. In particular, when an overmodulated
signal is input, the noise canceler may, in rare cases, malfunction. This is due to the fact that the IF detector output
has a waveform of the type shown in figure 43 due to the bands of the IF ceramic filters as shown below. (Here, the
antenna input is 60 dBµ, the ceramic filters are 150 kHz × 1 and 180 kHz × 2, f = 10 kHz, 180 kHz dev.) The noise
canceler reacts to the spikes (whiskers) generated due to this overmodulation, which results in distortion to the
audio output. (The spike components due to overmodulation occur due to the bands of the ceramic filters in the
tuner.) The following describes a method for resolving this problem. This incorrect operation due to
overmodulation is prevented by removing the spike components due to this overmodulation with a low-pass filter
consisting of a 1 kΩ resistor and a 2200 pF capacitor shown in figure 44. However, note that the FM separation
characteristics in the high band and the AM frequency characteristics will change.
IF audio output
f = 10 kHz,180 kHz dev
IF output
1 kΩ
Noise canceler input
+
H1 W1
2.5OU
31
2200 pF
–
30
1 µF
A12089
Fig. 44
–2.5OU
–19.00 µs
981.00 µs
Fig. 43
A12088
No. 6039-38/50
LA1784M
8. Multiplexer Block
• HCC (high cut control) frequency characteristics (pin 41)
When the HCC function operates, the frequency characteristics of the output signal are determined by the
capacitance of the external capacitor connected to pin 41.
20 kΩ
To the
matrix
VO
(dB)
41
C
A12090
Fig. 45
1
2πC × 20 kΩ
1
fC = ——————— [Hz]
2π × C × 20 kΩ
Frequency Characteristics
Fig. 46
f
(Hz)
A12091
Fig.47
10
Changes in the pin 41 capacitor capacitance (for a 100% high cut ratio)
0.001 µF
0µ
F
–10
0.0022 µF
–20
0.0047 µF
–30
F
1µ
0.0
Attenuation, HCC — dB
0
–40
–50
–60
3
VCC = 8.0 V
f = 98 MHz 100%mod
80 dBµ IN
5 7 100
2
3
5 7 1k
2
3
5 7 10k
2
3
Frequency, f — Hz
• Pilot canceler adjustment (pins 17 and 18)
Noise
30
canceler
input
–
To the
multiplexer
Fig. 48
Gate
Pilot
cancel
11
12 17
18
6800 pF 3.9 kΩ 0.01 µF 50 kΩ
A12092
The pilot canceler signal waveform (pin 19) is a 19 kHz signal that contains no third harmonic as shown in figure
48. Since this signal has the same phase as the pilot signal, no capacitor is required between pin 18 and ground.
Since it has no third harmonic component, excellent pilot cancellation can be acquired in both the left and right
channels by adjusting with a variable resistor.
No. 6039-39/50
LA1784M
• Separation adjustment (pin 19)
5 kΩ
To the
subdecoder
Larger
19
A12094
20 kΩ
0.047 µF
C
Fig. 49
A12093
The separation is adjusted by modifying the input level to the subdecoder with the variable resistor connected to
pin 19. Since only the sub-modulation level is changed by changing the variable resistor setting, the monaural
(main) output level is not changed. Furthermore, degradation of high band separation in the decoder can be avoided
if the impedance of the external capacitor (C) in the subchannel frequency band (23 to 53 kHz) is made sufficiently
smaller than the variable resistor.
9. MRC Circuit
VCC
2 µA
S-meter
100 Ω
FM
S-meter
DC buffer
MRC
30 kΩ
6.4 kΩ
10 kΩ
3.6 kΩ
24
+
QMRC
75 pF 1 kΩ
32
Noise amplifier
High-pass filter with
Fc = 70 kHz + amplifier
An external transistor equivalent
to the 2SC536 is required
Reason: A QMRC level shifter is
required to allow a simplified MRC
circuit to be used in the LA1781M.
27
+
C27
VCC
To the SNC, pin 28
A11768
Fig. 50
No. 6039-40/50
LA1784M
(1) When there is no AC noise on pin 32
V24 = V27–VBE
↑
QMRC
V27 is about 2.5 V when the antenna input is 60 dB or higher.
(2) Since the MRC noise amplifier gain is fixed, the MRC circuit is adjusted by reducing the AC input level.
32
+
Fig. 51
A11769
(3) The MRC attack and release are determined by C27 on pin 27.
Attack: 7 µA · C27 → 2 µA · C27
Release: 500 Ω · C27 → 100 Ω
Notes on the Noise Canceler
The noise canceler characteristics have been improved by implementing the circuit that determines the gate time in
logic. Since the time constant in earlier noise cancelers was determined by an RC circuit such as that shown in figure
52, the rise time shown in figure 53 was influenced by the values of the resistor and capacitor used. As a result the
noise exclusion efficiency was reduced by this delay in the rise time. In the LA1784M, this rise time was shortened by
implementing the circuit that determines the gate time in logic, allowing it to reliably exclude noise.
A11772
A11771
Fig. 52
Fig. 53
No. 6039-41/50
LA1784M
Gain Distribution (FM)
This section investigates the gain in each block in the LA1784M when the Sanyo recommended circuits are used.
(Test conditions)
Ambient temperature: 26°C
Antenna and mixer input frequency: 98.1 MHz
First and second IF input frequency: 10.7 MHz
The input levels when VSM = 2 V will be as follows.
ANT IN: 19 dBµ
MIX IN: 30 dBµ
1st IF IN: 42 dBµ
2nd IF IN: 60 dBµ
When the gains for each block are determined according to the above, the results are as follows.
RF GAIN: 11 dB
MIX GAIN: 12 dB
1st IF GAIN: 18 dB
1st IF IN 56 pin
FM
MIX IN 64 pin
RF
ANT IN
2nd IF IN 51 pin
11 dB
12 dB
18 dB
A11773
Fig. 54
No. 6039-42/50
LA1784M
(AM)
This section investigates the gain in each block in the LA1784M when the Sanyo recommended circuits are used.
(Test conditions)
Ambient temperature: 26°C
Antenna and mixer input frequency: 1 MHz
First and second mixer input frequency: 10.7 MHz
Second IF input frequency: 450 kHz
The gains at each stage will be as follows.
RF Gain (ANT IN-pin62): 17 dB
1st MIX Gain (pin62-pin56): 8 dB
1st IF Gain (pin55-pin53): 15 dB
AM
1st MIX
1st IF
2nd MIX
1st MIX
Gain
1st IF
Gain
2nd MIX
Gain
2nd IF
AM DET
RF
RF
Gain
2nd IF
Gain
A11774
Fig. 55
No. 6039-43/50
LA1784M
Input Circuits for Each Stage
[FM]
• Mixer input
• First IF input
75 Ω
0.022 µF
75 Ω
63
300 Ω 0.022 µF
56
75 Ω
64
75 Ω
VIN
Actual
measurement
fr = 10.7 MHz
A11776
A11775
• IF input
75 Ω
300 Ω
0.022 µF
51
330 Ω
75 Ω
50
0.022 µF
fr = 10.7 MHz
A11777
[AM]
• First mixer input
50 Ω
• Second mixer input
0.022 µF
62
50 Ω
50 Ω
0.022 µF
49
50 Ω
fr = RF
fr = 10.71 MHz (f2nd osc + 0.45 MHz)
A11778
• IF input
A11779
• Del input
50 Ω
0.022 µF
52
50 Ω
50 Ω
IFT
0.022 µF
45
50 Ω
fr = 450 kHz
fr = 450 kHz
A11780
A11781
No. 6039-44/50
LA1784M
Sample AM tuner Circuit with the LC72144 Used Together
IF
2nd MIX
CF
RF
CF
CF
450K
1st IF
300 Ω
XBUFF
LC72144
fosc
A11782
AM 1st IF
Step
FM IF
1
fOSC 10.25 MHz
10.7 MHz
10 kHz, 11 kHz
10.7 MHz
2
fOSC 10.35 MHz
10.8 MHz
9 kHz, 10 kHz
10.8 MHz
1st MIX
10.71 MHz
CF
RF
IF
CF
10 kΩ
CF
AF
62
59
60
56
53
49
54
1st OSC
52
2nd OSC
31
10.26 MHz
10.7 MHz
RF
63
64
60
59
NC
MPX
Lch
Rch
IF
CF
CF
56
53
Quadrature
detector
AF
51
A11783
No. 6039-45/50
LA1784M
Crystal Oscillator Element
Kinseki, Ltd.
Frequency: 10.26 MHz
CL: 20 pF
Model No.: HC-49/U-S
Coil Specifications
Sumida Electronics, Ltd.
[AM Block]
AM FILTEER (A286LBIS-15327)
AM OSC (V666SNS-213BY)
S
1
2
3
4
3
2
6
4
1
AM IF1 (7PSGTC-5001A=S)
3
AM IF2 (7PSGTC-5002Y=S)
2
1
6
1
S
S
S
AM loading (269ANS-0720Z)
4
6
AM ANT IN (385BNS-027Z)
4
3
2
1
4
3
4
S 2
3
6
2
6
1
S
6
S
AM RF amplifier (187LY-222)
0.1ø2UEW
[FM Block]
FM RF (V666SNS-208AQ)
FM ANT (V666SNS-209BS)
S
3
4
2
1
4
3
2
6
1
6
S
FM OSC (V666SNS-205APZ)
S
FM MIX (371DH-1108FYH)
S
3
4
3
C1
4
8
2
2
7
1
6
S
1
C2
6
S
FM DET (DM6000DEAS-8407GLF)
S
S
3
4
2
1
6
No. 6039-46/50
LA1784M
The Toko Electric Corporation
[AM Block]
AM FILTEER
AM OSC
4
3
1
2
3
2
6 0.1ø2UEW
1
6
4
AM IF1
AM IF2
4
3
4
3
2
2
6 0.05ø3UEW
1
AM loading
AM ANT IN
4
3
6 0.05ø3UEW
1
4
3
2
2
6 0.05ø3UEW
1
6 0.06ø3UEW
1
AM RF amplifier
0.1ø2UEW
[FM Block]
FM RF
FM ANT
S 3
4
4
3
2
ø0.1–2UEW
2
ø0.1–2UEW
6 S
1
6 S
1
FM OSC
3
FM MIX
S 3
4
2
5
1
6 S
4
2
1
ø0.07–2UEW
ø0.12–2UEW
6 S
FM DET
3
4
2
1
6 0.07ø2MUEW
No. 6039-47/50
First IF output — dBµ
Mixer output — dBµ
DCV — V
Output, noise, AM output — dB
Output, noise — dB
Total harmonic distortion, THD — %
HCC, SNC, RF AGC, muting voltage,
S-meter voltage, VSM — V
Output, noise, AM output, LR output — dB
LA1784M
Antenna input — dBµ
Mixer input — dBµ
Antenna input — dBµ
Antenna input — dBµ
Antenna input — dBµ
Input — dBµ
Input — dBµ
First IF input — dBµ
No. 6039-48/50
First IF output — dB
First IF output — dB
LA1784M
Frequency, — MHz
Antenna input — dBµ
S/N, AM output — dB
AGC on, separation, input level — dBµ
Frequency, — MHz
Ambient temperature, Ta — °C
Ambient temperature, Ta — °C
AM I/O Characteristics
20
Output, noise — dB
Separation, Sep — dB
0
VCC = 8.5 V
f = 1 MHz
mod = 1 k 30%
OUT
–20
–40
NOISE
–60
–80
–100
–20
0
M
VS
1.0
20
40
60
80
ANT input, IN — dBµ
100
140
120
140
4.0
3.0
2.0
z 30%
5.0
fm = 1 kH
3.0
6.0
z 80%
IF AGC
0
120
VCC = 8.5 V
f = 1 MHz
mod = 1 k 30% 80%
fm = 1 kH
4.0
Total harmonic distortion, THD — %
AGC, S-meter voltage — V
5.0
0
–20
100
AM Distortion
6.0
2.0
80
7.0
VCC = 8.5 V
f = 1 MHz
RF AGC
60
ANT input, IN — dBµ
AM DC Characteristics
7.0
40
20
Ambient temperature, Ta — °C
1.0
0
–20
0
20
40
60
80
100
120
140
ANT input, IN — dBµ
No. 6039-49/50
LA1784M
0
–20
40 dBµ
desire
mod
60 dBµ
OFF
80
µ
dB
µ
100 dB
50/3Ω
–60
–80
40
50Ω
fD=1MHz
fm=1kHz 30%
60
80
Bµ
30Ω
50Ω 50/3Ω VIN
65pF
fu=1040kHz
fm=400Hz 30% JIS ANT. DUMMY
100
120
140
60 dBµ
80 dBµ
–20
40 dBµ
–40
15pF ANT IN
50/3Ω
ANT input, IN — dBµ
40 d
–60
–80
40
desire
mod
OFF
Bµ
80 dBµ
100 dBµ
desire mod ON
dB
µ
µ
60 dBµ
∆400kHz
0d
100 dBµ
desire mod ON
AM Second-Channel Interference
Rejection Characteristics
10
∆40 kHz
40 dB
–40
20
80
Output, noise — dB
0
AM Second-Channel Interference
Rejection Characteristics
Output, noise — dB
20
60 dBµ
50/3Ω
fD = 1 MHz
fm = 1 kHz 30%
60
50Ω
80
15pF ANT IN
50/3Ω
30Ω
50Ω 50/3Ω VIN
65pF
fu = 1400 kHz
fm = 400 Hz 30% JIS ANT. DUMMY
100
120
140
ANT input, IN — dBµ
Specifications of any and all SANYO products described or contained herein stipulate the performance,
characteristics, and functions of the described products in the independent state, and are not guarantees
of the performance, characteristics, and functions of the described products as mounted in the customer’s
products or equipment. To verify symptoms and states that cannot be evaluated in an independent device,
the customer should always evaluate and test devices mounted in the customer’s products or equipment.
SANYO Electric Co., Ltd. strives to supply high-quality high-reliability products. However, any and all
semiconductor products fail with some probability. It is possible that these probabilistic failures could
give rise to accidents or events that could endanger human lives, that could give rise to smoke or fire,
or that could cause damage to other property. When designing equipment, adopt safety measures so
that these kinds of accidents or events cannot occur. Such measures include but are not limited to protective
circuits and error prevention circuits for safe design, redundant design, and structural design.
In the event that any or all SANYO products (including technical data, services) described or contained
herein are controlled under any of applicable local export control laws and regulations, such products must
not be exported without obtaining the export license from the authorities concerned in accordance with the
above law.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying and recording, or any information storage or retrieval system,
or otherwise, without the prior written permission of SANYO Electric Co., Ltd.
Any and all information described or contained herein are subject to change without notice due to
product/technology improvement, etc. When designing equipment, refer to the “Delivery Specification”
for the SANYO product that you intend to use.
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, 2001. Specifications and information herein are subject to
change without notice.
PS No. 6039-50/50