LA1781M_09 [SANYO]
For Car Radios Single-Chip Tuner IC; 对于汽车收音机单芯片调谐器IC
| 型号： | LA1781M_09 |
| 厂家： | 
SANYO SEMICON DEVICE |
| 描述： | For Car Radios Single-Chip Tuner IC |
| 文件： | 总48页 (文件大小：508K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Ordering number : EN6038A
Monolithic Linear IC
For Car Radios
LA1781M
Single-Chip Tuner IC
Overview
The LA1781M integrates all six blocks required in a car radio tuner on a single chip.
Features
• 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 LA1781 inherits the block arrangement of the LA1780M and supports pin-compatible designs.
Functions
• FM front end
• Multiplex
• FM IF
• AM up-conversion
• Noise canceller
• FM/AM switch
• MRC
Any and all SANYO Semiconductor Co.,Ltd. products described or contained herein are, with regard to
"standard application", intended for the use as general electronics equipment (home appliances, AV equipment,
communication device, office equipment, industrial equipment etc.). The products mentioned herein shall not be
intended for use for any "special application" (medical equipment whose purpose is to sustain life, aerospace
instrument, nuclear control device, burning appliances, transportation machine, traffic signal system, safety
equipment etc.) that shall require extremely high level of reliability and can directly threaten human lives in case
of failure or malfunction of the product or may cause harm to human bodies, nor shall they grant any guarantee
thereof. If you should intend to use our products for applications outside the standard applications of our
customer who is considering such use and/or outside the scope of our intended standard applications, please
consult with us prior to the intended use. If there is no consultation or inquiry before the intended use, our
customer shall be solely responsible for the use.
Specifications of any and all SANYO Semiconductor Co.,Ltd. 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.
71509 SY PC/32301TN (OT) No.6038-1/48
LA1781M
Specifications
Maximum Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
V
Maximum supply voltage
V
V
1 max
2 max
Pins 6, 40, and 61
9
12
CC
Pins 7, 45, 54, 59, and 60
V
CC
Allowable power dissipation
Operating temperature
Storage temperature
Pd max
Topr
Ta ≤ 55°C
950
mW
°C
°C
-40 to +85
Tstg
-40 to +150
Operating Conditions at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
V
Recommended supply voltage
V
V
V
Pins 6, 7, 40, 45, 54, 59, 60, and 61
Pin 26
8
5
CC
ST IND
V
CC
CC
Operating supply voltage range
op
7.5 to 9.0
V
Electrical Characteristics at Ta = 25°C, V
CC
= 8V, in the specified test circuit for the FM IF input
Ratings
Parameter
Symbol
Conditions
Unit
mA
min
typ
max
FM characteristics At the FM IF input
Current drain
I
-FM
No input, I40 + I45 + I54 + I59 + I60 + I61
60
94
110
CCO
Demodulation output
Pin 31 demodulation output
Channel balance
V
-FM
10.7MHz, 100dBμ, 1kHz, 100%mod, The pin 15 output
10.7MHz, 100dBμ, 1kHz, 100%mod, The pin 31 output
The ratio between pins 15 and 16 at 10.7MHz, 100dBμ, 1kHz
205
190
-1
310
295
0
415 mVrms
380 mVrms
O
O
V
-FM31
CB
+1
dB
%
Total harmonic distortion
Signal-to-noise ratio : IF
AM suppression ratio: IF
Muting attenuation
THD-FM mono 10.7MHz, 100dBμ, 1kHz, 100% mod, pin 15
0.3
82
1.0
S/N-FM IF
AMR IF
Att-1
10.7MHz, 100dBμ, 1kHz, 100% mod, pin 15
75
55
5
dB
dB
dB
10.7MHz, 100dBμ, 1kHz, fm = 1kHz, 30% AM, pin 15
68
10.7MHz, 100 dBμ, 1kHz. The pin 15
attenuation when V33 goes from 0 to 2V
10
15
25
38
Att-2
Att-3
Sep
10.7MHz, 100 dBμ, 1kHz. The pin 15
15
28
30
20
33
40
dB
dB
dB
attenuation when V33 goes from 0 to 2V*1
10.7MHz, 100 dBμ, 1kHz. The pin 15
attenuation when V33 goes from 0 to 2V*2
Separation
10.7MHz, 100dBμ, L + R = 90%, pilot = 10%. The pin 15 output
ratio
Stereo on level
ST-ON
The pilot modulation such that V26 < 0.5V
2.1
1.2
4.1
3.1
0.3
30
6.5
1.2
%
%
Stereo off level
ST-OFF
THD-Main L
PCAN
The pilot modulation such that V26 > 3.5V
Main total harmonic distortion
Pilot cancellation
10.7MHz, 100dBμ, L + R = 90%, pilot = 10%. The pin 15 signal
%
10.7MHz, 100dBμ, pilot = 10%.
The pin 15 signal/the pilot level leakage. DIN audio
20
1
dB
SNC output attenuation
HCC output attenuation
AttSNC
10.7MHz, 100dBμ, L - R = 90%, pilot = 10%.
V28 = 3V → 0.6V, pin 15
5
4.5
10
9
8.5
14
dB
dB
AttHCC-1
AttHCC-2
10.7MHz, 100dBμ, 10kHz, L + R = 90%, pilot = 10%.
V29 = 3V → 0.6V, pin 15
0.5
6
10.7MHz, 100dBμ, 10kHz, L + R = 90%, pilot = 10%.
V29 = 3V → 0.1V, pin 15
dB
Input limiting voltage
V
V
-LIM
100dBμ, 10.7MHz, 30% modulation. The IF input such that the
input reference output goes down by 3dB
33
40
47
dBμ
IN
Muting sensitivity
SD sensitivity
-MUTE
The IF input level (unmodulated) when V33 = 2V
27
54
35
62
43
70
dBμ
dBμ
IN
SD-sen1 FM
The IF input level (unmodulated) (over 100mV rms)
such that the IF counter buffer output goes on
SD-sen2 FM
54
130
0.0
62
200
0.1
70
dBμ
IF counter buffer output
Signal meter output
V
V
V
V
V
10.7MHz, 100dBμ, unmodulated. The pin 23 output
No input. The pin 24 DC output, unmodulated
50dBμ. The pin 24 DC output, unmodulated
70dBμ. The pin 24 DC output, unmodulated
100dBμ. The pin 24 DC output, unmodulated
100dBμ. The bandwidth when V33 = 2V, unmodulated
100dBμ, 0dBμ. The pin 33 DC output, unmodulated
270 mVrms
IFBUFF-FM
FM-1
SM
0.3
1.5
V
V
FM-2
FM-3
FM-4
0.4
1.0
SM
SM
SM
2.0
2.7
3.5
V
4.7
5.5
6.2
V
Muting bandwidth
Mute drive output
BW-MUTE
-100
150
0.00
220
0.03
290
0.20
kHz
V
V
MUTE
Continued on next page.
No.6038-2/48
LA1781M
Continued from preceding page.
Ratings
typ
Parameter
Symbol
Conditions
Unit
min
max
FM FE Mixer input
N-AGC on input
V
V
83MHz, unmodulated.
The input such that the pin 2 voltage is 2.0V or below
81
88
95
dBμ
dBμ
NAGC
W-AGC on input
83MHz, unmodulated. The input such that the pin 2
voltage is 2.0V or below. (When the keyed AGC is set to 4.0V.)
104
110
116
WAGC
Conversion gain
A. V
V
83MHz, 80dBμ, unmodulated. The FE CF output
19
85
30
48 mVrms
Oscillator buffer output
NC Block NC input (pin 30)
Gate time
BUFF-FM No input
110
165 mVrms
OSC
T
f = 1kHz, for a 1μs, 100-mVp-o pulse
55
40
μs
GATE
Noise sensitivity
SN
The level of a 1kHz, 1μs pulse input that starts
mVp-o
noise canceller operation. Measured at pin 30.
NC effect
SN-NC
The pulse rejection effect provided by the noise canceller.
5
For a repeated 1μs wide pulse, frequency = 10kHz,
150mVp-o. The ratio of the FM mode pin 15 output
referenced to the AM mode pin 15 output (effective value)
Multipath rejection circuit MRC input (pin 27)
MRC output
V
V24 = 5V
2.2
10
2.3
15
2.4
V
MRC
MRC-ON
MRC operating level
The pin 32 input level at f = 70kHz such that
pin 24 goes to 5V and pin 27 goes to 2V
20 mVrms
AM characteristics AM ANT input
Practical sensitivity
Detector output
S/N-30
1MHz, 30dBμ, fm = 1kHz, 30% modulation, pin 15
1MHz, 74dBμ, fm = 1kHz, 30% modulation, pin 15
1MHz, 74dBμ, fm = 1kHz, 30% modulation, pin 31
20
130
110
59
dB
V
V
V
-AM
195
175
64
270 mVrms
230 mVrms
O
Pin 31 detector output
AGC F.O.M.
-AM31
O
1MHz, 74dBμ, referenced to the output, the input amplitude
such that the output falls by 10dB. Pin 15
69
dB
AGC-FOM
Signal-to-noise ratio
Total harmonic distortion
Signal meter output
S/N-AM
1MHz, 74dBμ, fm = 1kHz, 30% modulation
1MHz, 74dBμ, fm = 1kHz, 80% modulation
No input
47
52
0.3
0.2
4.4
230
98
dB
%
THD-AM
1
0.5
6.1
V
V
V
AM-1
0.0
3.5
185
92
V
SM
AM-2
1MHz, 130dBμ, unmodulated
V
SM
Oscillator buffer output
BUFF-AM1 No input, the pin 15 output
OSC
mVrms
dBμ
dBμ
dBμ
Wide band AGC sensitivity
W-AGCsen1
W-AGCsen2
SD-sen1AM
1.4MHz, the input when V46 = 0.7V
104
95
1.4MHz, the input when V46 = 0.7V (seek mode)
83
89
SD sensitivity
1MHz, the ANT input level such that the IF counter output turns
24
30
36
on.
SD-sen2AM
1MHz, the ANT input level such that the SD pin goes to the on
state.
24
30
36
dBμ
IF buffer output
V
-AM
1MHz, 74dBμ, unmodulated. The pin 23 output
200
290
mVrms
IFBUFF
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 200kΩ.
*2. When the resistor between pin 58 and ground is 30kΩ.
No.6038-3/48
LA1781M
Package Dimensions
unit : mm (typ)
3159A
Pd max -- Ta
1000
950
Mounted on a specified board :
900
17.2
14.0
40 × 80 × 1.3mm3
glass epoxy board
800
700
600
48
33
Independent IC
32
49
500
400
300
200
64
17
100
0
1
16
--40
--20
0
20
40
60
80
100
0.8
0.35
0.15
(1.0)
Ambient temperature, Ta -- °C
SANYO : QIP64E(14X14)
Function List
1. FM Front End (Equivalent to the Sanyo LA1193)
(1) Double input type double balanced mixer
(2) Pin diode drive AGC output
(3) MOSFET second gate drive AGC output
(4) Keyed AGC adjustment pin
4. Multiplex Functions
(1) Adjustment-free VCO circuit
(2) Level follower type pilot canceller circuit
(3) HCC (high cut control)
(4) Automatic stereo/mono switching
(5) Differential IF amplifier
(6) Wide band AGC sensitivity setting pin, and narrow
band AGC sensitivity setting pin
(5) VCO oscillation stop function (AM mode)
(6) Forced monaural
(7) SNC (stereo noise controller)
(8) Stereo display pin
(7) Local oscillator
(9) Anti-birdie filter
2. FM IF
(1) IF limiter amplifier
5. AM
(2) S-meter output (also used for AM) 6-stage pickup
(3) Multipath detection pin (shared FM signal meter)
(4) Quadrature detection
(1) Double balanced mixer (1st, 2nd)
(2) IF amplifier
(3) Detection
(5) AF preamplifier
(6) AGC output
(4) RF AGC (narrow/wide)
(5) Pin diode drive pin
(7) Band muting
(6) IF AGC
(8) Weak input muting
(7) Signal meter output (also used for FM)
(8) Local oscillator circuits (first and second)
(9) Local oscillator buffer output
(10) IF counter buffer output (also used by the FM IF)
(11) SD (IF counter buffer on level) adjustment pin
(12) SD output (active high) (also used for AM)
(13) Wide AGC
(9) Soft muting adjustment pin
(10) Muting attenuation adjustment pin
(11) IF counter buffer output (also used for AM)
(12) SD (IF counter buffer on level) adjustment pin
(13) SD output (active high) (also used for AM)
3. Noise Canceller
(14) Detection output frequency characteristics
adjustment pin (low cut, high deemphasis)
(15) AM stereo buffer
(1) High-pass filter (first order)
(2) Delay circuit based low-pass filter (fourth order)
(3) Noise AGC
(4) Pilot signal compensation circuit
(5) Noise sensitivity setting pin
(6) Function for disabling the noise canceller in AM
mode
6. MRC (multipath noise rejection circuit)
7. AM/FM switching output (linked to the FM V
)
CC
No.6038-4/48
LA1781M
Operating Characteristics and Symbols Used in the Test Circuit Diagrams
(1) Switches (SW)
Switch on = 1, SW off = 0
There are two switches that use signal transfer.
1) SW2 : switches between the mixer input and the IF input.
2) SW4 : switches between noise canceler input and IF output + noise canceler input.
(2) 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 83MHz signal.
AC3
Used for FM IF, noise canceler, and MPX testing. Outputs a 10.7MHz signal. Stereo modulation must be possible.
Used for AM testing. Outputs 1 MHz and 1.4MHz signals.
AC4
AC5
Used with the MRC. Can also be used for AF and OSC.
(3) Power supply
V
8V
CC
V
V
V
1
2
3
5V
SD, stereo, seek/stop
Keyed AGC, Mute ATT
HCC, SNC, SASC (MRC)
CC
CC
CC
0.1V/0.7V/2V/4V
0.1V/0.6V/2V
These levels must be
variable.
(4) (a) Switches
Parameter
is supplied to pin 62.
ON
OFF
AM
SW1
SW2
SW3
SW4
AM/FM switching. The FE V
FM
FE IF OUT (A)
CC
FM IF switching. Pin 51/FE output
For conversion gain testing
AC3 (B)
Conversion gain measurement (A)
AC1 (A)
Other/purposes
Other/purposes
For switching between noise canceler input and IF output + noise
canceler.
SW5
SW6
SW7
SW8
SW9
High-speed SD
High-speed SD
STOP
Other/purposes
SEEK/STOP (IF BUFF ON/OFF)
MUTE ATT 200kΩ
Seek (IF buffer output)
MUTE 200kΩ
OFF
MUTE ATT 30kΩ
MUTE 30kΩ
OFF
For pilot cancellation testing
When pilot cancellation is used
MUTE OFF
When pilot cancellation is not used
MUTE ON
SW10 Mute off (pin 33)
(b) Trimmers (variable resistors)
VR1
Separation adjustment
VR2
Pilot cancellation adjustment
(5) Test Points
(a) DC voltages
VD1
VD2
VD3
VD4
VD5
VD6
VD7
FM RF AGC voltage
AM/FM SD, AM Tweet, FM stereo indicator
AM/FM S-meter
Pin 2
Pin 26
Pin 24
Pin 27
Pin 33
Pin 46
Pin 8
MRC output
Mute drive output
AM antenna damping voltage
N.C. Gate time
(b) AC voltages
VA1
VA2
VA3
VA4
VA5
AM/FM OSC Buff
Pin 4
First IF output
Pin 53 → CF → pin 51 load level (10.7MHz)
Pin 23 (10.7MHz/450kHz)
Pin 15 (AF)
IF counter buffer
MPX OUT Left ch
MPX OUT Right ch
Pin 16 (AF)
No.6038-5/48
LA1781M
Pin Descriptions
Pin No.
1
Pin function
Antenna damping drive
Pin description
Equivalent circuit
V
An antenna damping current flows
when the RF AGC voltage (pin 2)
Pin 62
CC
ANT
RF
AGC
reaches V
- V .
D
CC
1000pF
300Ω
100Ω
1
100Ω
1000pF
2
RF AGC
Used to control the FET
second gate.
V
CC
FET
2ND GATE
12kΩ
2
+
DAMPING
DRIVER
ANT
N
W
AGC
DET
AGC
DET
V
CC
KEYED
AGC
3
4
F.E.GND
OSC
Oscillator connection.
V
CC
The transistor and capacitors
required for the oscillator circuit are
integrated on the chip.
4
25pF
2kΩ
V
T
20pF
7
AM OSC
AM first oscillator.
7
V
This circuit can oscillator up to the
SW band.
CC
An ALC circuit is included.
A
L
C
Continued on next page.
No.6038-6/48
LA1781M
Continued from preceding page.
Pin No.
Pin function
Pin description
Equivalent circuit
8
9
Noise AGC sensitivity
AGC adjustment
After setting up the medium field
(about 50dBμ) sensitivity with the
noise sensitivity setting pin (pin 8), set
the weak field (about 20 to 30dBμ)
sensitivity with the AGC adjustment
pin (pin 9).
3kΩ
3kΩ
15kΩ
200Ω
8
9
3kΩ
+
0.47μF
1MΩ
0.01μF
11
12
Memory circuit connection
Recording circuit used during noise
canceller operation.
0.01μF
6800pF
3.9kΩ
13
12
11
V
CC
Differential
amp
Gate
circuit
LPF
13
Pilot input
Pin 13 is the PLL circuit input pin.
V
CC
30kΩ
PLL
N.C
12
13
0.01μF
14
N.C, MPX, MRC, GND
Ground for the N.C., MPX, and MRC
circuits.
Continued on next page.
No.6038-7/48
LA1781M
Continued from preceding page.
Pin No.
Pin function
Pin description
Deemphasis
Equivalent circuit
15
16
MPX output (left)
MPX output (right)
V
CC
50μs : 0.015μF
75μs : 0.022μF
3.3kΩ
3.3kΩ
15
16
0.015μF
0.015μF
17
Pilot canceller signal output
Adjustment is required since the pilot
signal level varies with the
V
CC
sample-to-sample variations in the IF
output level and other parameters.
20kΩ
10kΩ
6.7kΩ
17
18
0.01μF
100kΩ
18
Pilot canceller signal output
Pin 18 is the output pin for the pilot
canceller signal.
V
CC
1.5kΩ
17
18
0.01μF
100kΩ
19
Separation
Use a trimmer to adjust the
subdecoder input level.
DECODER
Composit
signal
5kΩ
adjustment pin
(The output level is not modified in
mono and main modes.)
19
30kΩ
0.047μF
Continued on next page.
No.6038-8/48
LA1781M
Continued from preceding page.
Pin No.
20
Pin function
Pin description
Equivalent circuit
VCO
The oscillator frequency is 912Hz.
KBR-912F108
CSB
912
JF104
(Kyocera Corporation)
CSB-912JF108
20
V
REF
(Murata Mfg. Co., Ltd.)
10pF
21
22
PHASE COMP.
PHASE COMP.
V
REF
15kΩ
15kΩ
+
19kΩ
21
22
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.
+
- -
4.9V
AM MUTE
50kΩ
+
--
1.3V
IF counter
buffer
The voltage V23 switches between
the following three modes.
During FM reception :
V
CC
10kΩ
150Ω
+
--
SW
5V :
Seek mode
50F
2.5V : Forced SD mode
0V :
Reception mode
AM reception
SD circuit
(two modes : 0 and 5V)
Seek mode
23
51kΩ
5V :
0V :
Reception mode
STOP
IF
BUFF.
Forced
SEEK
SD:2.5V 5V
Continued on next page.
No.6038-9/48
LA1781M
Continued from preceding page.
Pin No.
24
Pin function
Pin description
Equivalent circuit
AM/FM signal meter
Fixed-current drive signal meter
output.
V
CC
32
26
27
Dedicated FM signal meter
In AM mode, pin 32 outputs a
1mA current. Thus the HCC
circuit is turned off.
FM
S-meter
32
24
10kΩ
AM
S-meter
10kΩ
AM/FM
SW
Outputs a 1-mA
current during AM
reception
AM/FM
SW
MRC
Stereo indicator for the SD pin
The voltage V23 switches between
three modes as follows.
FM reception :
5V :
The SD pin operates linked
to the IF counter buffer.
AM/FM
SD
Stereo
indicator
2.5V : Forced SD mode: operates
as the SD pin.
Seek/stop
switching
0.7V : Reception mode: stereo
indicator
26
AM reception : (two modes : 0 and 5V)
5V :
0V :
Operates as the seek SD pin.
Reception mode. Not used.
100kΩ
V
DD
MRC control voltage time
constant
The MRC detector time constant is
determined by a 100Ω resistor and C2
when discharging and by the 2μA
current and C2 when charging.
V
CC
V
CC
2μA
C2
27
100Ω
Pin 28
28
SNC control input
The sub-output is controlled by a 0 to
1V input.
V
REF
28
Continued on next page.
No.6038-10/48
LA1781M
Continued from preceding page.
Pin No.
29
Pin function
Pin description
Equivalent circuit
HCC control input
The high band frequency output is
controlled by a 0 to 1V input.
It can also be controlled by the MRC
output.
V
REF
Use a resistor of at least 100kΩ when
controlling with the pin 32 FM S-meter
signal.
32
29
+
1μF
30
31
Noise canceller input
AM/FM detector output
Pin 30 is the noise canceller input.
V
CC
The input impedance is 50kΩ.
FM
detector
output
Pin 31 is the AM and FM detector
output
31
In FM mode, this is a low-impedance
output.
10kΩ
In AM mode, the output impedance is
10kΩ.
V
CC
To improve the low band separation,
use a coupling capacitor of over 10μF.
1μF
AM
detector
+
30
Noise
canceller
50kΩ
4.2V
32
IF S-meter output and MRC
DC input
FM S-meter output block
MRC AC input block
V
CC
Adjust the external 1kΩ resistor to
attenuate the MRC AC input and
control the circuit.
32
10kΩ
+
1μF
1kΩ
MRC input
Continued on next page.
No.6038-11/48
LA1781M
Continued from preceding page.
Pin No.
33
Pin function
Pin description
Equivalent circuit
Mute drive output
•The muting time constant is
determined by an external RC circuit
as described below.
C1
+
0.1μF
Attack time : T = 10kΩ × C1
A
Release time : T = 50kΩ × C1
R
33
•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
V
CC
50kΩ
10kΩ
MUTE
AMP.
SEEK
OFF
Ground pin 33 through a 4kΩ
resistor.
SOFT HOLE
MUTE DET
Band
muting
50kΩ
SD circuit
34
35
36
37
AGC
•The resistor R1 determines the width
of the band muting function.
Increasing the value of R1 narrows
the band.
0.1μF
V
R1
REF
QD output
QD input
V
CC
C
V
REF
Reducing the value of R1 widens the
band.
R2
37
36
35
34
•Null voltage
V
CC
When tuned, the voltage between
pins 34 and 37, V
34 - 37
The band muting function turns
, will be 0V.
Quadrature
detector
on when |V | ≥ 0.7V.
34 - 37
= 4.9V
V
37
HOLE
DET
3pF
1kΩ
IF limiter amplifier
Band
muting
38
FM SD ADJ
A 130μA current flows from pin 38
and, in conjunction with the external
resistance R, determines the
comparison voltage.
R
SD ADJ
38
130μA
+
- -
SD
Comparator
24
S-meter
Continued on next page.
No.6038-12/48
LA1781M
Continued from preceding page.
Pin No.
39
Pin function
Pin description
Equivalent circuit
Keyed AGC
The keyed AGC operates when the
voltage created by dividing the pin 24
S-meter output voltage by the 6.4 and
3.6kΩ resistors becomes lower than
the voltage determined by the resistor
between pin 39 and ground.
24
AM stereo buffer
S-meter
6.4kΩ
3.6kΩ
Comparator
This pin also is used as the AM stereo
IF buffer pin.
KEYED
AGC
+
--
39
90μA
1.3V
V
CC
AM IF out
50pF
150Ω
41
HCC capacitor
The HCC frequency characteristics
are determined by the external
capacitor connected at this pin.
V
CC
20kΩ
+
20kΩ
41
2200pF
42
AM L.C. pin
This pin is used to change the
frequency characteristics of the
unneeded audio band under 100Hz in
AM mode to produce a clear audio
signal.
V
CC
C
42
V
CC
Note : The LC capacitor must be
connected between this pin
DET
and V
(pin 40).
CC
50kΩ
50kΩ
1kΩ
1kΩ
This is because the detector
circuit operates referenced to
+
- -
V
.
CC
The cutoff frequency f is determined
C
by the following formula.
f
= 1/2π × 50kΩ × C
C
43
Pilot detector
Inserting a 1MΩ resistor between pin
V
CC
43 and V
mode.
will force the IC to mono
CC
19kHz∠0°
BIAS
30kΩ
30kΩ
30kΩ
+
43
1μF
+
Continued on next page.
No.6038-13/48
LA1781M
Continued from preceding page.
Pin No.
44
Pin function
Pin description
Equivalent circuit
IF AGC
G1 ; Used for time constant switching
during seeks.
V
CC
+
C
0.022μF
2.2μF
• Reception
240kΩ
44
τ = 2.2μF × 300kΩ
• Seek
42
V
CC
τ = 2.2μF × 10Ω
The external capacitors are
DET
50kΩ
50kΩ
connected to V
.
CC
This is because the IF amplifier
operates referenced to V
.
CC
IF
AGC
G1
SEEK
ON
10Ω
45
IF output
The IF amplifier load
Pin 40 V
CC
45
Pin 40 V
CC
DET
46
AM antenna damping
drive output
I46 = 6mA (maximum)
V
CC
This is the antenna damping
current.
Wide band AGC input
50pF
46
100Ω
20kΩ
V
CC
W.AGC AMP.
ANT DAMPING
DRIVER
47
FM muting on level adjustment
Modify the value of the external
30kΩ
resistor to adjust the muting on level.
R
47
V
CC
140μA
- -
+
Inverter
Pin 24
MUTE
Continued on next page.
No.6038-14/48
LA1781M
Continued from preceding page.
Pin No.
Pin function
Pin description
Equivalent circuit
48
57
RF AGC bypass
RF AGC
RF AGC rectification capacitor
The low frequency distortion is
determined as follows :
V
CC
Increasing C48 and C57 improves the
distortion but makes the response
slower.
5.6V
10kΩ
+
- -
Antenna
damping
48
Reducing C48 and C57
+
aggravates the distortion but makes
the response faster.
3.3μF
For AGC use
57
+
47μF
50
51
IF bypass
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.
FM IF input
2.6V
10kΩ
10kΩ
50
51
330Ω
0.022μF
IF in
52
IF input
The input impedance is 2kΩ.
2kΩ
100Ω
52
53
56
IF amplifier output
IF amplifier input
• Input and output pin or the first IF
amplifier
V
CC
• Inverting amplifier
V56 = 2V
IF OUT 53
Input impedance : R = 330Ω
IN
300Ω
V53 = 5.3V
300Ω
Output impedance
2.75V
R
= 330Ω
OUT
IF IN 56
Continued on next page.
No.6038-15/48
LA1781M
Continued from preceding page.
Pin No.
Pin function
Pin description
Equivalent circuit
54
49
Mixer output : 130μA
The mixer coil connected to the pin 54
Pin 40 V
CC
Mixer input
mixer output must be wired to V
CC
(pin 40).
Pin 40 V
CC
The pin 49 mixer input
Impedance is 330Ω
54
OSC
49
330Ω
55
58
W-AGC IN
Pins 55 and 58 include built-in DC cut
capacitors.
W-AGC
N-AGC
Pin 62
AM SD ADJ
V
CC
The AGC on level is determined by
the values of the capacitors C1 and
C2.
N-AGC IN
Muting attenuation
adjustment pin
Pin 55 functions as the SD sensitivity
adjustment pin in AM mode.
30pF
55
58
The output current I55 is 50μA, and
V55 varies depending on the value of
the external resistor.
C1
50pF
The SD function operates by
comparing V55 with the S-meter
voltage.
MIX
IN
C2
50μA
+
- -
MIX
OUT
AM SD
Signal meter
59, 60
63, 64
Mixer output
Mixer input
Double balanced mixer.
Pins 59 and 60 are the mixer
10.7MHz output
1ST.IF
O
S
C
59
60
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.
V
CC
30Ω
V
Note :The lines for pins 63 and 64
must be kept separated from
the lines for pins 59 and 60.
CC
C1
63
64
5pF
C2
RF AMP
5pF
620Ω
620Ω
Continued on next page.
No.6038-16/48
LA1781M
Continued from preceding page.
Pin No.
6
Pin function
Pin description
Pin 6 functions both as the FM front
end V and the AM/FM switching
Equivalent circuit
Front end V
switching
AM/FM
CC
CC
circuit.
510Ω
V
CC
SD
AM/FM
switching circuit
+
- -
6
+
V6 voltage
When 8V → FM
OPEN → AM
Mode
FM.F.E
AGC
100kΩ
3.3V
8V
3
GND
62
1st MIX
INPUT
First mixer input
AM 1st
MIX
The input impedance is about 10kΩ.
to RF
Amp.
62
10kΩ
2.1V
10
AM 2nd OSC
Crystal oscillator circuit
The Kinseki, Ltd. HC-49/U-S and
10kΩ
a C of 20pF must be used.
L
20pF
33pF
5.6V
to 2nd
MIX
10
X tal
No.6038-17/48
LA1781M
Block Diagram
V
CC
0.022μF
TO AM STEREO
GND
(IF OUT)
+
10kΩ
+
+
+
+
+
0.1μF
240kΩ
10kΩ
37 36
RFAGC
MUTE DRIVE
33
30Ω
0.022μF
0.022μF
1μF
100kΩ
48
47
46
45
44
43
42
41
40
39
38
35
34
1kΩ
620Ω
1MH
100μH
FM
ANT
D
OSC
BUFF
49
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
OSC
METER
50kΩ
AM LEVEL ADJ
AM HC
FC18
DET OUT
FM IF IN
100μH
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
MUTE
AMP
+
0.022μF
Q.DET
IF limiter
amplifier
220Ω
+
8200pF
30MH
0.022μF
BUFF
NC-IN
HCC
100Ω
1μF
HOLE
DET
MUTE
DRIVE
AM IF IN
IF
AGC
AMVSM
AM SD
FMVSM
FM SD
DET
L.C.
510kΩ
ANTD
0.022μF
DC-C AFC
DET CLAMP
SNC
FM IF OUT
IF BUFF
1μF
MRC
10kΩ
+
AM SD ADJ
AM MIX OUT
MIX
SNC
HCC
IF
REG
AM/FM
SW
RF AGC
WB AGC
TWEET
FM WB AGCIN
FE IF IN
20kΩ
SEEK→AM/FM SD
STOP→FM ST IND.
GND
AM FM
VREF
AM/FM
S-METER
5V
0.47μF
SEEK
SW
FF
VCO
STOP
PHASE
COMP
19k<90k
200kΩ
62pF
300Ω
SD/ST
IND
MAIN
W.B.AGC
RF AGC
HC
0.022μF
FF
VCO
MUTE ATT
5.6kΩ
+
19k<0
2kΩ
AMP
KEYED
AGC
INPUT
+
V
30Ω
CC
0.22μF
PILOT
DET
1μF
HPF
LPF
TRIG
CSB912JF104
MIX
AM/FM
FEV
CC
P-CAN
NOISE
AMP
PICAN
INPUT
--
+
0.022μF
0.047μF 20kΩ
FF
38k<0
AMP
V
CC
SEP.ADJ
BUFF
8pF
30Ω
BUFF
AM
1ST
FF
AGC TRIG
GATE
SUB MAT
DEC RIX
1000pF
5pF
100kΩ
COUNTER
OSC
22pF 22pF
ANT
D
5pF
0.01μF
PI.CAN ADJ
1000pF
1
2
3
4
5
6
7
8
9
10
AM
OSC
11
12
13
14
15
MPX
OUT
16
+
18pF
6800pF 0.01μF
200kΩ
GND
0.1μF
30kΩ
10pF
+
5pF
100Ω
0.022μF
30kΩ
GND
300pF
10.26MHz
NC MPX GND
30kΩ
18pF
10μF
10μF
R
L
10μF
10μF
0.22μF
1μF
10kΩ
2.2kΩ
10kΩ
10μF
0.01μF
3SK583
+B
12V
100pF 100pF 100pF 100pF
0.22μF
18 17
22pF
+
20
19
16
15
14
13
12
11
V
PD
V
FM IN AM IN
5.6V
SS
DD
7.2MHz
LC7216M
CE
2
CI
3
CL
DO
5
FM/AM
10
+
1
4
6
7
8
9
9.1V
22pF
100pF
CE
CI
CL
DO
RDS
ADC MUTE SD/MONO
ST
R ON
LC867148
No.6038-18/48
LA1781M
AC Characteristics Test Circuit
+
+
+
Ω
1 0 0 k
1 0 0 k
Ω
Ω
1 0 0 k
Ω
Ω
1 0 k
1 M
+
+
F μ 1
F μ
F μ
0 . 0 1 5
0 . 0 1 5
R I G H T C H .
L E F T C H .
F μ 0 . 1
A F C I N
F μ 0 . 4 7
N . C . M P X G N D
Q D O U T
Q D I N
+
Ω
1 0 k
R E F
V
Ω
Ω
1 0 k
1 M
F M S D A D J .
2 2 k
Ω
Ω
6 . 8 k
K E Y E D A G C
F μ 0 . 2 2
F μ 0 . 4 7
Ω 1 M
F μ 0 . 0 1
1 0 k
+
F μ 1 0 0
Ω
Ω
1 0 k
C H C C
2 2 0 0 p F
3 0 0 p F
A M L C
F μ
0 . 0 2 2
P I L O T D E T
F μ 1
F μ
0 . 0 2 2
F μ
0 . 0 2 2
F μ 2 . 2
A M / F M O S C B U F F
5 p F
I F 7
Ω
3 0 k
F E G N D
R F A G C
M U T E O R A D J
1 5 k
Ω
F μ 1
A N T D
F μ 3 . 3
Ω
3 3 0
C C
F M V
F M G N D
Ω
3 3 0
3 9 p F
Ω
1 0 0 k
Ω
Ω
2 0 0
3 0 0
Ω 3 0
F μ
0 . 0 2 2
Ω
2 0 k
F μ
0 . 0 2 2
Ω 5 0
+
F μ 4 7
Ω 5 0
Ω
1 0 0 k
Ω
Ω
2 0 0 k
3 0 k
+
F μ
0 . 0 2 2
6 . 8 M H
+
No.6038-19/48
LA1781M
Test Conditions
Switch states
Parameter
Symbol
-FM
SW1
ON
SW2
SW3
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
SW4
SW5
SW6
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
SW7
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
-
SW8
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
-
SW9
SW10
Current drain
I
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
a
a
a
a
-
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
a
a
a
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
b
-
ON
-
-
CCO
Demodulation output
Pin 31 demodulation output
Channel balance
V
-FM
ON
-
ON
O
V
-FM31
ON
-
ON
-
O
CB
ON
-
ON
-
Total harmonic distortion (FM) THD-FM mono
ON
-
ON
-
Signal-to-noise ratio : IF
AM suppression ratio : IF
Muting attenuation
S/N-FM IF
AMR IF
Att-1
ON
-
ON
-
ON
-
ON
-
ON
-
ON
-
Att-2
ON
-
ON
-
Att-3
ON
-
ON
-
Separation
Separation
ST-ON
ST-OFF
ON
-
ON
-
Stereo on level
Stereo off level
ON
-
ON
-
ON
-
ON
-
Main total harmonic distortion THD-Main L
ON
-
ON
-
Pilot cancellation
PCAN
ON
-
OFF/ON
-
SNC output attenuation
HCC output attenuation 1
HCC output attenuation 2
Input limiting voltage
Muting sensitivity
AttSNC
AttHCC-1
AttHCC-2
ON
-
ON
-
ON
-
ON
-
ON
-
ON
-
V
-LIM
ON
-
ON
ON
-
IN
V
-MUTE
ON
-
OFF
ON
OFF
-
ON
IN
SD sensitivity 1
SD-sen1 FM
SD-sen2 FM
ON
ON
-
SD sensitivity 2
ON
ON
-
IF counter buffer output
Signal meter output (FM)
V
ON
ON
-
IFBUFF-FM
V
V
V
V
FM-1
FM-2
FM-3
FM-4
ON
ON
-
SM
SM
SM
SM
ON
-
ON
-
ON
-
ON
-
ON
-
ON
-
Muting bandwidth
Mute drive output
N-AGC on input
W-AGC on input
Conversion gain
Oscillator buffer output
Gate time 1
BW-MUTE
ON
-
ON
-
V
ON
-
ON
-
-
MUTE-100
V
ON
-
-
NAGC
V
ON
ON
-
-
-
WAGC
A.V
ON
ON
-
-
-
V
ON
ON
-
-
-
OSCBUFF-FM
τGATE1
SN
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
-
-
-
Noise sensitivity
NC effect
ON
-
-
-
-
SN-NC
ON/OFF
ON
-
-
-
-
MRC output
V
-
-
-
-
MRC
MRC operating level
Practical sensitivity
Detection output
Pin 31 detection output
AGC F.O.M.
MRC-ON
S/N-30
ON
-
-
-
-
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
-
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
-
-
V
V
V
-AM
-
-
-
-
-
O
-AM31
-
-
-
-
-
O
-
-
-
-
-
AGC-FOM
Signal-to-noise ratio
S/N-AM
-
-
-
-
-
Total harmonic distortion (AM) THD-AM
-
-
-
-
-
Signal meter output (AM)
V
V
V
AM-1
AM-2
-
-
-
-
-
SM
-
-
-
-
-
SM
Oscillator buffer output
1
-
-
-
-
-
OSCBUFF-AM
Wide band AGC sensitivity
W-AGCsen1
W-AGCsen2
SD-sen1 AM
SD-sen2 AM
-
-
-
-
-
-
-
-
-
-
SD sensitivity
-
-
-
-
-
-
-
-
-
-
IF buffer output
V
-
-
-
-
-
IFBUFF-AM
No.6038-20/48
LA1781M
Usage Notes
1. Notes on V
Pin 40
and Ground
CC
V
for the FM IF, AM, NC, MPX, and MRC blocks
CC
Pin 25
Ground for the FM IF and AM blocks
Pin 14
Ground for the NC, MPX, and MRC blocks
Pin 61
V
V
for the FM front end, AM first mixer, and first oscillator blocks
CC
*Pin 6
for the FM front end and AGC blocks, and the AM/FM switching pin
CC
Pin 3
Ground for the FM front end, first mixer, and first oscillator blocks
2. Notes on AM Coil Connection
The V used for the first oscillator coil connected to pin 7 must be at the same potential as pin 61.
CC
Connect to the IFT connected with pin 45, and to the MIX coil connected with pin 54. V
potential as pin 40.
must be at the same
CC
3. AM/FM Switching
Pin 6 is also used as the FM front end and RF AGC V
CC
V6pin
Pin 6 voltage
Mode
FM
8
8
OPEN
AM
3.3
AM
FM
AM
Fig. 1
4. Notes on the FM Front End
Notes on interference rejection characteristics
• Intermodulation characteristics
The LA1781M 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.
Δf -- AGC Sensitivity
When Δf = 0, 98.1MHz
110
100
The wide AGC
sensitivity when
pin 39 is 5V.
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
Δf -- MHz
Fig. 2
No.6038-21/48
LA1781M
• 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 Δf < 1.5MHz) is controlled
• Effective in resolving second-channel attenuation problems.
by the field strength of the desired station.
The narrow AGC sensitivity is controlled by a voltage (V ) that is under
23
• Allows effective resolution of second-channel attenuation problems
0.5V.
without under 0.5 V. degrading three-signal characteristics.
The wide AGC can operate even when V = 0 (when the desired station
23
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.
Δf -- AGC on Level (ANT input) Fig. 3
Δf -- AGC on Level (ANT input) Fig. 4
Pin 55 capacitor : 3pF
110
100
110
100
90
90
Pin 55 capacitor : 10pF
Pin 58 capacitor :
10pF
80
80
keyed AGC
keyed AGC
70
70
39
39
Pin 58 capacitor :
47pF
60
60
5V
50
50
--5 --4 --3 --2 --1
0
1
2
3
4
5
--5 --4 --3 --2 --1
0
1
2
3
4
5
Δf -- MHz
Δf -- MHz
W-AGC, N-AGC -- f
Fig. 5
70
80
90
100
110
120
AGC input level frequency
130
140
characteristics such that
AGC (pin 2) falls under 2V.
V
RF
7
2
3
5
7
2
3
5
7
100
2
3
5
1.0
10
Frequency, f -- MHz
No.6038-22/48
LA1781M
3D AGC Sensitivity Characteristics
AGC sensitivity
Wide AGC sensitivity
ΔF
1
2
Second-channel
attenuation improvement
Narrow AGC sensitivity
3
Desired station AGC sensitivity
4
V
(Desired station field strength)
23
Fig. 6
Figure 6 3D AGC Sensitivity - Δf, V characteristics
23
• 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 V ≥ 0.5V
23
The above selectivity and V when V < 0.5V
23 23
• 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.
Δf -- AGC on Level (ANT input)
When Δf = 0, 98.1MHz
110
f
D
= 98.1MHz
Second-dhannel pad
100
90
ANT IN
V
IN
80
70
fu = 98.1MHz + Δf
60
50
--5 --4 --3 --2 --1
0
1
2
3
4
5
Δf -- MHz
Fig. 7
No.6038-23/48
LA1781M
Notes on 3D AGC (Keyed AGC)
V
CC
W-AGC
DET
55
N-AGC
DET
58
S-meter
90μA
+
--
V
CC
+
--
1
2
+
39
24
ANT
DUMPING
VS-meter
Fig. 8
• The antenna damping current from the pin due to the pin diode flows when the V2 pin reaches the V
• The narrow AGC operates as follows.
- V
level.
BE
CC
When pin V39 > pin V24 : The narrow AGC turns off.
When pin V39 < pin V24 : The narrow AGC turns on.
No.6038-24/48
LA1781M
• The LA1781M includes two AGC circuits in its front end block.
(1) Antenna input limiter using a pin diode.
(2) FET second gate control
The AGC input pin is pin 59, and the AGC circuit turns on when a signal of about 30mVrms is input.
AGC activation
The pin diode drive circuit turns on when VCC - V2 is greater than or equal to about 1V, and input limitation is
applied to the antenna circuit. In application circuits, there will be an attenuation of about 30 to 40dB. 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, V
the source is 0. Note that if a depletion-type MOSFET is used, AGC will not be applied unless V
G2-S
, between the second gate and
is less than 0.
G2-S
V2 AGC Characteristics
Fig. 9
9
8
7
6
5
4
3
2
1
fr = 98.0Hz
V
= 8V
CC
Ta = 25°C
Range where AGC level AGC level due
the AGC does due to the to the MOSFET
not operate
pin diode :
about 35dB
second gate :
about 35dB
0
--10
0
10 20 30 40 50 60 70 80 90 100 110 120 130 140
ANT IN -- dBμ
• Mixer
The mixer circuit in this IC is a double-balanced mixer with both
balanced input and balanced output.
Input circuit type
64
59
60
63 62
Emitter input
Input impedance : 25Ω
Due to optimized device geometry, emitter current, the bias, this IC
achieves the following performance.
MIX
Mixer input usable sensitivity : 15dBμ
Mixer input IMQS : 90.5dBμ
(For an oscillator level of 200mVrms)
OSC
* The mixer input IMQS is defined as :
fr = 98.8MHz, no input
fu1 = 98.8MHz, 1kHz, 30% modulation
fu2 = 99.6MHz, no modulation
The interference 1 and 2
input levels such that
generated intermodulation
output signal-to-noise ratio
becomes 30dB when an
interference signal with the
same level as the mixer input
is input, and distortion occurs
in the mixer.
Mixer circuit
Fig. 10
No.6038-25/48
LA1781M
• Oscillator
Figure 11 shows the type of oscillator circuit used in this IC. It includes both an oscillator and an oscillator buffer.
V
CC
18pF
4
25pF
20pF
AM/FM
OSC BUFFER OUT
5
VT
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
Fig. 12
Specifications
Input impedance : 330Ω
Output impedance : 330Ω
Gain : 20dB
No.6038-26/48
LA1781M
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.
+
--
R
R
4.9V
+
--
R
Band
muting
Muting
drive
output
HOLE
CLET
STEREO
IND
S-meter
IF count buffer
+
--
FM IF
39
24
33
23
26
5V
IF count output
SD
STEREO/MONO
2.5V 5V
Fig. 13
Figure 14 shows the relationship between the FM SD, the IF count buffer output, the S-meter, and the muting drive
output.
Larger
S-meter
V
V
V
values
of R
24
38
33
33
Smaller values of R
33
V
V
33
over 0.7V
33
over 0.7V
V
26
5V
On as an
SD signal
SD
ON
SD
ON
Mono
0.7V
Stereo
V
23AC
IF count
buffer
OFF
OFF
IF counter output off
2.5V
V
23DC
5V
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 0.7V),
when this pin is shorted to ground (0.1V or lower)
the IC will operate in forced mono mode.
Fig. 14
No.6038-27/48
LA1781M
• 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
I
24
24
R
C
24
24
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
Muting time constants
Attack : 10kΩ × C33
Release : 50kΩ × C33
10kΩ
50kΩ
Attack
Release
33
C
33
Fig. 16
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.6038-28/48
LA1781M
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.
IF BUFFER
F.E.
IF
AMP
0.022μF
Test system capacitance
5V
The 10.7MHz feeds back through ground.
Fig. 18
• FM Muting control pin (pin 47) (R47 : 30kΩ variable resistor)
The -3dB limiting sensitivity can be adjusted with R47.
FM Soft Muting (1)
Fig. 19
DET out
10
0
R47 = 7.5kΩ
15kΩ
--10
--20
--30
--40
--50
10kΩ
20kΩ
--60
--70
--20
--10
0
10
20
30
40
Antenna input -- dBμ
• FM muting attenuation adjustment (pin 58)
The muting attenuation can be switched between the three levels of -20, -30, and -40dB 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
R58
Open
200kΩ
30kΩ
Mute ATT
-20dB
100Ω
R
58
-30dB
-40dB
33
The attenuation can be set by making R33 smaller as listed
in the table above.
R
33
Fig. 20
No.6038-29/48
LA1781M
FM Soft Muting (2)
Fig. 21
DET out
FM Soft Muting (3)
Fig. 22
DET out
10
0
10
0
R47 = 7.5kΩ
R47 = 7.5kΩ
10kΩ
10kΩ
--10
--20
--30
--40
--50
--10
--20
--30
--40
--50
15kΩ
15kΩ
58
200kΩ
58
30kΩ
20kΩ
20kΩ
--60
--70
--60
--70
--20
--10
0
10
20
30
40
--20
--10
0
10
20
30
40
Antenna input -- dBμ
Antenna input -- dBμ
V
CC
Mute amp.
(VCA)
Quadrature detector
200kΩ
R
R
+
--
+
--
N-AGC
Mute
drive
Limiter
R
58
33
31
DET out
To MIX out
Open
200kΩ
30kΩ
Fig. 23
• FM muting off function
Forcing this pin to the ground level turns muting off.
Detecter
output
0
1
When the pin is at the ground level, the noise convergence will
be 10dB and the -3dB limiting sensitivity will be about 0dBμ.
20
Antenna input
Fig. 24
No.6038-30/48
LA1781M
• 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 5dBμ. The amount of
attenuation is referenced to an antenna input of 60dBμ, fm = 1kHz, and a 22.5kHz dev output, and is variable from
10dB to 40dB when there is no input. Thus one feature of this circuit is that the weak input noise attenuation and
the -3dB limiting sensitivity for over 5dBμ inputs can be set independently.
Hall Detection Output -- Antenna Input Characteristics Fig. 25
5
Area muted by Hall detection
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 5dBμ.
36
33
Vb
+
Va
0.1μF
0
0
Fig. 26
(3) Unique features
One unique feature of the LA1781M is that if there are adjacent stations such that f = 98.1MHz and f =
1
SM
2
97.9MHz, a search operation will not stop at 98.0MHz. Since V
= 0V and V
= 3.6V at 98.0MHz in the
AFC
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, V
Mute
will go low, thus preventing incorrect stopping of the search.
will be set to 1.2V (over 0.7V) and the SD signal
No.6038-31/48
LA1781M
Unique Featuers of the LA1781M Hall Detection circuit (1) Fig. 27
Unique Featuers of the LA1781M Hall Detection circuit (2) Fig. 28
2
2
When the tuner is moved in 50kHz steps.
With a 51kΩ resistor between pins 37 and 34.
With the SD sensitivity adjusted to be 20dBμ.
When the tuner is moved in 50kHz steps.
With a 51kΩ resistor between pins 37 and 34.
With the SD sensitivity adjusted to be 20dBμ.
f
1
ANT
IN
1
0
1
0
f
2
--1
6
--1
6
4
4
2
0
2
0
6
4
6
4
2
0
8
6
4
2
0
8
6
4
f
= 97.9MHz, 120dBμ
f = 97.9MHz, 40dBμ
2
2
fm = 400Hz, 22.5kHz dev.
= 98.1MHz, 120dBμ
fm = 400Hz, 22.5kHz dev.
f = 98.1MHz, 40dBμ
1
f
1
fm = 1kHz, 22.5kHz dev.
fm = 1kHz, 22.5kHz dev.
2
0
2
0
97.7
97.8
97.9
98.0
98.1
98.2
98.3
97.7
97.8
97.9
98.0
98.1
98.2
98.3
Frequency, fr -- MHz
Frequency, fr -- MHz
• Notes on the quadrature input level
When a strong field is being received the quadrature signal input (pin 36) requires a 200mVrms 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 10kΩ resistor between pins 36 and 37.)
When the pin 36 input level falls below 160mVrms, the Hall detection circuit operates and the pin 33 mute drive
output voltage increases. Therefore, when pin 36 input is from 160 to under 200mV 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
200mVrms or higher.
Pin 33 VMute -- QD Input Level Fig. 29
With pins 34 and 37 shorted.
With 5V applied to pin 24.
SA208 + LA1781M IF Input Characteristics Fig. 30
6
5
4
3
2
4 0.8
3 0.6
2 0.4
1 0.2
THD 1kHz
75kHz dev
--100 --80 --60 --40 --20
--120
0
20 40 60 80 100 120
Δf -- kHz
With the resistorbetween
pins 36 and 37 open.
--0.2
--0.4
75Ω
0.022μF
75Ω
Δf = 0 →
+
10.7kHz
With a 10kΩ resistor
SG
between pins 36 and 37
1
0
--0.6 Voltage between pins 37 and 34
--0.8 (referenced to the pin 37 voltage)
36
37
10.7MHz
94 96
LA1888M
100 102
92
98
104
106
QD input level -- dBμ
No.6038-32/48
LA1781M
Detector output
MPX OUT
Pin 36 AC level
R
V
QDIN
36-37
O
Open
330mVrms
280mVrms
235mVrms
200mVrms
10kΩ
• Band Muting Adjustment Procedure
The muting bandwidth can be modified as shown in figure 31 with the resistor RBW between pin 34 and 37.
R
-- Muting Bandwidth Fig. 31
BW
280
240
200
160
120
80
R
BW
+
+
1μF
0.47μF
SA208
Sumida
10kΩ
37 36
35
34
ANT IN 98MHz 100dBμ
40
0
2
3
5
7
2
3
5
7
2
1.0
10
100
Resistor R
between pins 34 and 37 -- kΩ
BW
6. AM
• AM AGC system
The LA1781M 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.
R
W
1st MIX 10.7MHz CF
2nd MIX 450kHz CF
IF Amp.
DET
62
49
52
31
RF
V
CC
CC
42
44
1st OSC
X'tal
240kΩ
2.2μF
V
Amp.
IF AGC
46
Middle AGC IN
Narrow AGC IN
Wide AGC IN
ANT
DUMPING
RF AGC
57
48
+
+
47μF
3.3μF
Fig. 32
No.6038-33/48
LA1781M
AM AGC f characteristics
Fig. 33
100
Wide AGC
Operates for wide
band interference
Wide AGC
Operates for
wide band
90
interference
Middle AGC
Middle AGC
Operates for
Operates for
interference within
±±7kHz of the
received frequency.
80 interference within
±±7kHz of the
received frequency.
70 Narrow AGC
Operates at the
received frequency.
60
1000
800
900
1100
1200
Frequency -- Hz
Wide Band AGC Circuit
Fig. 34
120
Received frequency :
30Ω
1MHz
0.022μF
46
110
100
90
50Ω
50Ω
--6dB
0.022μF
SG
ANTD
510Ω
0.022μF
80
70
2
3
5
7
2
3
5
1.0
10
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
30Ω
0.022μF
V
CC
620Ω
1MH
100μH
FC18
57
62
100μH
+
Fig. 35
No.6038-34/48
LA1781M
• 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 5V reference voltage as shown in
figure 36.
S-meter
AM IF
Comparator
V
CC
+
--
IF buff amp.
50pF
50μA
55
24
23
26
100kΩ
100kΩ
0.47μF
0.022μF
IF buffer
5V
51kΩ
5V
SD
Seek
Fig.36
Figure 37 shows the relationship between the AM SD, the IF count buffer, and the S-meter.
Larger
S-meter
values
of R
V
24PIN
55
V
V
55
26
Smaller values of R
SD on
55
V
23AC
23DC
IF buffer on
5V
OFF
V
Pin 55 AM SD adjustment pin
0V
Fig.37
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.6038-35/48
LA1781M
• AM high band cut and detector output level adjustment methods
The pin 31 AM and FM tuner output has an impedance of 10kΩ 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.
V
CC
FM
detector
31
R31
C31
V
CC
+
AM
detector
10kΩ
30
Noise
canceler
input
50kΩ
Fig. 39
• AM stereo system pins
To the AM stereo decoder
V
CC
GND
400mVrms
450kHz output
IFT
45
39
V
CC
50pF
150Ω
KEYED AGC
IF AMP.
Fig. 40
No.6038-36/48
LA1781M
• AM low band cut adjustment method
The AM low band frequency characteristics can be adjusted with C42, which is inserted between pin 42 and V
.
CC
Since the detector is designed with V
CC
as the reference, C42 must be connected to V .
CC
Detector Output -- Frequency Fig. 42
20
10
80%mod
0.1μF
V
CC
With no
C42
C
used.
31
0
30%mod
C31pin
= 6800pF
Using SEP 450H
=
42
0.022μF
--10
--20
--30
50kΩ
50kΩ
10kΩ
0.047μF
+
--
10kΩ
To pin 31
0.1μF
AM
detecter
C
42pin
10kΩ
--40
--50
fr = 100kHz
fm = 10kHz 30%mod
Fig. 41
3
5
7
2
3
5
7
2
3
5
7
2
3
5
7
2
0.01
0.1
1.0
10
Frequency -- Hz
7. Noise Canceler Block
• The noise canceler input (pin 30) has an input impedance of about 50kΩ. Check the low band frequency
characteristics carefully when determining the value of the coupling capacitor used. Note that f will be about 3Hz
C
when a 1μF 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 50dBμ) with pin 8 (the noise sensitivity setting pin), and
then set the AGC level for a weak field (20 to 30dBμ) 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 10kHz 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 60dBμ, the ceramic filters are 150kHz × 1 and 180kHz × 2, f = 10kHz, 180kHz 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 1kΩ resistor and
a 2200pF capacitor shown in figure 44. However, note that the FM separation characteristics in the high band and the
AM frequency characteristics will change.
H1 W1
2.5OU
IF audio output
f = 10kHz,180kHz dev
IF output
31
Noise canceler input
1kΩ
- -
30
1μF
2200pF
Fig.44
--2.5OU
--19.00ms
981.00μs
Fig. 43
No.6038-37/48
LA1781M
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.
20kΩ
To The
VO
Matrix
(dB)
41
C
f
Fig. 45
1
(Hz)
2πC × 20kΩ
1
f =
C
[Hz]
2π × C × 20kΩ
Fig. 46
Frequency Characteristics Fig. 47
Changes in the pin 41 capacitor capacitance (for a 100% high cut ratio)
10
0
0.001μF
--10
--20
--30
--40
0.0022μF
0.0047μF
--50
--60
V
= 8.0V
CC
f = 98MHz 100%mod
80dBμ IN
3
5
7
2
3
5
7
2
3
5
7
10k
2
3
100
1k
Frequency, f -- Hz
• Pilot canceler adjustment (pins 17 and 18)
NCoise
30
--
To the
multiplexer
canceler
input
Gate
Pilot
cancel
11
12 17
18
6800pF 3.9kΩ 0.01μF 50kΩ
Fig. 48
The pilot canceler signal waveform (pin 19) is a 19kHz 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.6038-38/48
LA1781M
• Separation adjustment (pin 19)
5kΩ
To The
subdecoder
Larger
19
20kΩ
C
0.047μF
Fig. 49
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 53kHz) is made sufficiently smaller
than the variable resistor.
9. MRC Circuit
V
CC
2μA
100Ω
FM
S-meter
S-meter
DC buffer
MRC
QMRC
30kΩ
6.4kΩ
3.6kΩ
10kΩ
1kΩ
75pF
24
32
27
Noise amplifiter
High-pass filter with
Fc = 70 kHz + amplifiter
+
+
C27
V
CC
An external transistor equivalent
to the 2SC536 is required
To the SNC, pin 28
Reason : A QMRC level shifter is
required to allow a simplified MRC
circuit to be used in the LA1781M.
Fig. 50
No.6038-39/48
LA1781M
(1) When there is no AC noise on pin 32
V
= V - V
27
24
BE
↑
QMRC
V27 is about 2.5V when the antenna input is 60dB 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
(3) The MRC attack and release are determined by C27 on pin 27.
Attack : 7μA × C27 → 2μA × C27
Release : 500Ω × C27 → 100Ω
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 LA1781M, this rise time was shortened by
implementing the circuit that determines the gate time in logic, allowing it to reliably exclude noise.
Fig. 52
Fig. 53
No.6038-40/48
LA1781M
Gain Distribution (FM)
This section investigates the gain in each block in the LA1781M when the Sanyo recommended circuits are used.
(Test conditions)
Ambient temperature : 26°C
Antenna and mixer input frequency : 98.1MHz
First and second IF input frequency : 10.7MHz
The input levels when V
= 2V will be as follows.
SM
ANT IN : 19dBμ
MIX IN : 30dBμ
1st IF IN : 42dBμ
2nd IF IN : 60dBμ
When the gains for each block are determined according to the above, the results are as follows.
RF GAIN : 11dB
MIX GAIN : 12dB
1st IF GAIN : 18dB
1st IF IN 56 pin
FM
MIX IN 64 pin
RF
ANT IN
2nd IF IN 51 pin
11dB
12dB
18dB
Fig. 54
(AM)
This section investigates the gain in each block in the LA1781M when the Sanyo recommended circuits are used.
(Test conditions)
Ambient temperature : 26°C
Antenna and mixer input frequency : 1MHz
First and second mixer input frequency : 10.7MHz
Second IF input frequency : 450kHz
The gains at each stage will be as follows.
RF Gain (ANT IN-pin62) : 17dB
1st MIX Gain (pin62-pin56) : 8dB
1st IF Gain (pin55-pin53) : 15dB
AM
1st MIX
1st IF
2nd MIX
2nd IF
AM DET
RF
RF
Gain
1st MIX
Gain
1st IF
Gain
2nd MIX
Gain
2nd IF
Gain
Fig. 55
No.6038-41/48
LA1781M
Input Circuits for Each Stage
[FM]
• Mixer input
• First IF input
0.022μF
75Ω
75Ω
0.022μF
300Ω
75Ω
63
64
56
75Ω
V
IN
fr = 10.7MHz
Actual
measurement
• IF input
0.022μF
75Ω
300Ω
51
50
75Ω
330Ω
0.022μF
fr = 10.7MHz
[AM]
• First mixer input
• Second mixer input
0.022μF
0.022μF
50Ω
50Ω
62
49
50Ω
50Ω
fr = RF
fr = 10.71MHz (f2nd osc + 0.45MHz)
• IF input
• Del input
IFT
0.022μF
0.022μF
50Ω
50Ω
52
45
50Ω
50Ω
fr = 450kHz
fr = 450kHz
No.6038-42/48
LA1781M
Sample AM tuner Circuit with the LC72144 Used Together
2nd MIX
IF
CF
CF
CF
RF
450K
1st IF
300Ω
XBUFF
fosc
LC72144
AM 1st IF
10.7MHz
10.8MHz
Step
FM IF
1
2
f
f
10.25NHz
10.35NHz
10kHz, 11kHz
9kHz, 10kHz
10.7MHz
10.8MHz
OSC
OSC
1st MIX
IF
10.71MHz
10kΩ
CF
CF
CF
RF
AF
62
59
60
56
53
49
54
52
1st OSC
2nd OSC
Lch
31
NC
MPX
Rch
10.26MHz
IF
10.7MHz
AF
CF
CF
QUADRATURE
DETECTOR
RF
63
64
60
59
56
53
51
No.6038-43/48
LA1781M
Crystal Oscillator Element
Kinseki, Ltd.
Frequency : 10.26MHz
CL
: 20pF
Model No. : HC-49/U-S
Coil Specifications
Sumida Electronics, Ltd.
[AM Block]
AM FILTEER (SA-1051)
AM OSC (SA-359)
S
1
2
3
3
2
1
4
6
4
6
AM IF1 (SA-264)
AM IF2 (SA-1063)
3
4
3
4
2
2
S
1
6
1
6
S
S
S
AM loading (SA-1062)
AM ANT IN (SA-1048)
3
4
3
4
2
2
1
6
1
6
S
S
AM RF amplifier (RC875-222J)
0.1φ2UEW
[FM Block]
FM RF (SA-1060)
FM ANT (SA-1061)
S
3
2
1
4
3
2
1
4
6
6
S
S
FM OSC (SA-1052)
FM MIX (SA-266)
S
3
2
1
4
C1
8
3
2
1
4
6
7
6
C2
S
S
FM DET (SA-208)
S
3
S
4
2
1
6
No.6038-44/48
LA1781M
The Toko Electric Corporation
[AM Block]
AM FILTEER (A286LBIS-15327)
AM OSC (V666SNS-213BY)
3
2
1
4
1
2
3
6
6
4
0.1φ2UEW
AM IF1 (7PSGTC-5001A = S)
AM IF2 (7PSGTC-5002Y = S)
3
2
1
4
3
2
1
4
6
6
0.05φ3UEW
0.05φ3UEW
AM loading (269ANS-0720Z)
AM ANT IN (385BNS-027Z)
3
2
1
4
3
2
1
4
6
6
0.05φ3UEW
0.06φ3UEW
AM RF amplifier (187LY-222)
0.1φ2UEW
[FM Block]
FM RF (V666SNS-208AQ)
FM ANT (V666SNS-209BS)
3
2
1
4
3
2
1
4
S
φ0.1--2UEW
S
φ0.1--2UEW
S
6
6
FM OSC (V666SNS-205APZ)
FM MIX (371DH-1108FYH)
3
2
1
4
3
2
1
4
5
6
S
φ0.12--2UEW
S
φ0.07--2UEW
S
6
FM DET (DM6000DEAS-8407GLF)
3
2
1
4
6
0.07φ2MUEW
No.6038-45/48
LA1781M
FM I/O Characteristics
FM I/O Characteristics
10
0
10
9
R ch
OUT30% mod
RF AGC
8
--10
--20
--30
--40
7
6
V
SM
5
4
3
2
L ch
V
MUTE
--50
AM OUT
V
HCC
--60
--70
NOISE
1
0
V
SNC
--20
0
20
40
60
80
100
120
140
--20
0
20
40
60
80
100
120
140
140
140
120
Antenna input -- dBμ
FM Distortion
Antenna input -- dBμ
FM Sensitivity Suppression
10
9
10
0
fm = 1kHz
22.5k dev
OUT
8
7
6
5
4
--10
--20
--30
--40
--50
3
2
NOISE
--60
--70
fm = 1kHz 100%
1
0
fm = 1kHz 30%
--20
0
20
40
60
80
100
120
140
140
120
--20
0
20
40
60
80
100
120
Antenna input -- dBμ
FM Gain Distribution (2)
Antenna input -- dBμ
FM Gain Distribution (1)
10
0
8
7
6
1st IF
ANT IN
--10
33
--20
5
MUTE OFF
SNC, HCC OFF
--30
--40
--50
4
3
2
AM OUT
--60
--70
1
0
NOISE
--20
0
20
40
60
80
100
120
--20
0
20
40
60
80
100
120
Input -- dBμ
Mixer I/O Characteristics
Input -- dBμ
First IF I/O Characteristics
120
110
100
90
120
110
100
90
Input from
pin 64 only
80
80
0.022μF
300Ω
75Ω
56
53
V.V.
V.V.
59
60
0.022μF
70
60
70
60
V
IN
40
50
60
70
80
90
100
110
40
50
60
70
80
90
100
110
Mixer input -- dBμ
First IF input -- dBμ
No.6038-46/48
LA1781M
First IF Frequency Characteristics
FM Antenna Input Temperature Characteristics (1)
10
0
400
300
200
100
75kHz (100%mod)
--10
--20
0.022μF
--30
300Ω
75Ω
53
V.V.
100
56
22.5kHz (30%mod)
0.022μF
--40
--50
V
IN
2
80dBμ IN
0
7
2
3
5
7
3
5
7
2
3
--40
--20
0
20
40
60
80
100
1.0
10
Frequency -- MHz
FM Antenna Input Temperature Characteristics (2)
Frequency -- MHz
FM Antenna Input Temperature Characteristics (3)
100
90
30
20
10
80
70
60
50
40
S/N
0
Separation
30
20
--10
--40
--40
--20
0
20
40
60
80
100
--20
0
20
40
60
80
100
Ambient temperature, Ta -- °C
Ambient temperature, Ta -- °C
FM Antenna Input Temperature Characteristics (4)
AM I/O Characteristics
= 8.5V
50
40
30
20
20
0
V
CC
f = 1MHz
OUT
mod = 1k 30%
--20
--40
--60
80dB IN
NOISE
40dB IN
20dB IN
10
0
--80
--100
--40
--20
0
20
40
60
80
100
--20
0
20
40
60
80
100
120
140
Ambient temperature, Ta -- °C
AM DC Characteristics
ANT input, IN -- dBμ
AM Distortion
V
7.0
6.0
5.0
4.0
3.0
2.0
7.0
6.0
5.0
4.0
3.0
2.0
V
= 8.5V
= 8.5V
CC
f = 1MHz
CC
f = 1MHz
mod = 1k 30% 80%
RF AGC
1.0
0
1.0
0
--20
0
20
40
60
80
100
120
140
--20
0
20
40
60
80
100
120
140
ANT input, IN -- dBμ
ANT input, IN -- dBμ
No.6038-47/48
LA1781M
AM Second-Channel Interference
Rejection Characteristics
AM Second-Channel Interference
Rejection Characteristics
20
0
20
0
Δ40kHz
Δ400kHz
100dBμ
100dBμ
desire mod ON
desire mod ON
80dBμ
80dBμ
--20
--40
--20
--40
40dBμ
40dBμ
desire
desire
mod
OFF
mod
60dBμ
OFF
60dBμ
15pF
15pF
ANT IN
50/3Ω
50/3Ω
ANT IN
50Ω
50/3Ω
50Ω
50/3Ω
--60
--80
--60
--80
f
= 1MHz
f
= 1MHz
D
D
30Ω
65pF
30Ω
65pF
fm = 1kHz 30%
fm = 1kHz 30%
V
V
IN
50Ω 50/3Ω
50Ω 50/3Ω
IN
fu = 1040kHz
fu = 1400kHz
JIS ANT. DUMMY
JIS ANT. DUMMY
fm = 400Hz 30%
fm = 400Hz 30%
40
60
80
100
120
140
40
60
80
100
120
140
ANT input, IN -- dBμ
ANT input, IN -- dBμ
SANYO Semiconductor Co.,Ltd. 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 Semiconductor Co.,Ltd.
products described or contained herein.
SANYO Semiconductor Co.,Ltd. strives to supply high-quality high-reliability products, however, any and all
semiconductor products fail or malfunction with some probability. It is possible that these probabilistic failures or
malfunction could give rise to accidents or events that could endanger human lives, trouble that could give rise
to smoke or fire, or accidents 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 Semiconductor Co.,Ltd. products described or contained herein are
controlled under any of applicable local export control laws and regulations, such products may require 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 consent of SANYO Semiconductor 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 Semiconductor Co.,Ltd. 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.
Upon using the technical information or products described herein, neither warranty nor license shall be granted
with regard to intellectual property rights or any other rights of SANYO Semiconductor Co.,Ltd. or any third
party. SANYO Semiconductor Co.,Ltd. shall not be liable for any claim or suits with regard to a third party's
intellctual property rights which has resulted from the use of the technical information and products mentioned
above.
This catalog provides information as of July, 2009. Specifications and information herein are subject
to change without notice.
PS No.6038-48/48
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