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Ordering number : ENN6038
Monolithic Linear IC
LA1781M
Single-Chip Tuner IC for Car Radios
Overview
The LA1781M 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
-- 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.
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
Package Dimensions
Unit:mm
3159-QIP64E
[LA1781M]
17.2 14.0 0.35
33 48 49 32
1.0 1.6 1.0
0.8
1.6 1.0
0.15
17.2 14.0
Allowable power dissipation, Pdmax -- mW
1.0
64 1 16
Independent IC
3.0max 0.8
Mounted on a 40 x 80 x 1.3 mm3 glass epoxy printed circuit board
0.8
17
0.1 2.7
15.6
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
32301TN (OT) No. 6038-1/50
LA1781M
Specifications
Maximum Ratings at Ta = 25C
Parameter Maximum supply voltage Allowable power dissipation Operating temperature Storage temperature Symbol VCC1 max VCC2 max Pd max Topr Tstg Pins 6, 40, and 61 Pins 7, 45, 54, 59, and 60 Ta 55C Conditions Ratings 9 12 950 -40 to +85 -40 to +150 Unit V V mW C C
Operating Conditions at Ta = 25C
Parameter Recommended supply voltage Operating supply voltage range Symbol VCC VCCST IND VCC op Conditions Pins 6, 7, 40, 45, 54, 59, 60, and 61 Pin 26 Ratings 8 5 7.5 to 9.0 Unit V V V
Operating Characteristics at Ta = 25C, VCC= 8.0V, in the specified test cricuit for the FM IF input
Ratings Parameter Symbol Conditions min 60 205 190 -1 typ 94 310 295 0 0.3 75 55 5 15 28 30 2.1 1.2 82 68 10 20 33 40 4.1 3.1 0.3 20 1 0.5 6 33 27 54 54 10.7 MHz, 100 dB, unmodulated. The pin 23 output No input. The pin 24 DC output, unmodulated 50 dB. The pin 24 DC output, unmodulated 70 dB. The pin 24 DC output, unmodulated 100 dB. The pin 24 DC output, unmodulated 100 dB. The bandwidth when V33 = 2 V, unmodulated 100 dB, 0 dB. The pin 33 DC output, unmodulated 130 0.0 0.4 2.0 4.7 150 0.00 30 5 4.5 10 40 35 62 62 200 0.1 1.0 2.7 5.5 220 0.03 9 8.5 14 47 43 70 70 270 0.3 1.5 3.5 6.2 290 0.20 1.2 6.5 15 25 38 max 110 415 380 +1 1 [FM Characteristics] At the FM IF input Current drain Demodulation output Pin 31 demodulation output Channel balance Total harmonic distortion Signal-to-noise ratio: IF AM suppression ratio: IF ICCO-FM VO-FM VO-FM31 CB THD-FM mono S/N-FM IF AMR IF Att-1 Muting attenuation Att-2 Att-3 Separation Stereo on level Stereo off level Main total harmonic distortion Pilot cancellation SNC output attenuation Separation ST-ON ST-OFF THD-Main L PCAN AttSNC AttHCC-1 HCC output attenuation AttHCC-2 Input limiting voltage Muting sensitivity SD sensitivity IF counter buffer output Vi-lim Vi-mute SD-sen1 FM SD-sen2 FM VIFBUFF-FM VSM FM-1 Signal meter output VSM FM-2 VSM FM-3 VSM FM-4 Muting bandwidth Mute drive output BW-mute VMUTE-100 No input, I40 + I45 + I54 + I59 + I60 + I61 10.7 MHz, 100dB, 1 kHz, 100%mod, The pin 15 output 10.7 MHz, 100dB, 1 kHz, 100%mod, The pin 31 output The ratio between pins 15 and 16 at 10.7 MHz, 100 dB, 1 kHz 10.7 MHz, 100 dB, 1 kHz, 100% mod, pin 15 10.7 MHz, 100 dB, 1 kHz, 100% mod, pin 15 10.7 MHz, 100 dB, 1 kHz, fm = 1 kHz, 30% AM, pin 15 10.7 MHz, 100 dB, 1 kHz. The pin 15 attenuation when V33 goes from 0 to 2 V 10.7 MHz, 100 dB, 1 kHz. The pin 15 attenuation when V33 goes from 0 to 2 V*1 10.7 MHz, 100 dB, 1 kHz. The pin 15 attenuation when V33 goes from 0 to 2 V*2 10.7 MHz, 100 dB, L+R = 90%, pilot = 10%. The pin 15 output ratio The pilot modulation such that V26 < 0.5 V The pilot modulation such that V26 > 3.5 V 10.7 MHz, 100 dB, L+R = 90%, pilot = 10%. The pin 15 signal 10.7 MHz, 100 dB, pilot = 10%. The pin 15 signal/the pilot level leakage. DIN audio 10.7 MHz, 100 dB, L-R = 90%, pilot = 10%. V28 = 3 V 0.6 V, pin 15 10.7 MHz, 100 dB, 10 kHz, L+R = 90%, pilot = 10%. V29 = 3 V 0.6 V, pin 15 10.7 MHz, 100 dB, 10 kHz, L+R = 90%, pilot = 10%. V29 = 3 V 0.1 V, pin 15 100 dB, 10.7 MHz, 30% modulation. The IF input such that the input reference output goes down by 3 dB The IF input level (unmodulated) when V33 = 2 V The IF input level (unmodulated) (over 100 mV rms) such that the IF counter buffer output goes on mA mVrms mVrms dB % dB dB dB dB dB dB % % % dB dB dB dB dB dB dB dB mVrms V V V V kHz V unit
Continued on next page.
No. 6038-2/50
LA1781M
Continued from preceding page. Ratings Parameter [FM FE Mixer Input N-AGC on input W-AGC on input Conversion gain Oscillator buffer output [NC Block] NC input (pin 30) Gate time Noise sensitivity GATE1 SN f = 1 kHz, for a 1-s, 100-mV p-o pulse The level of a 1 = kHz, 1-s pulse input that starts noise canceller operation. Measured at pin 30. The pulse rejection effect provided by the noise canceller. For a repeated 1-s 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) 55 40 s mVp-o VN-AGC VWAGC A.V VOSCBUFFFM 83 MHz, unmodulated. The input such that the pin 2 voltage is 2.0 V or below 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.) 83 MHz, 80 dB, unmodulated. The FE CF output No input 81 104 19 85 88 110 30 110 95 116 48 165 dB dB mVrms mVrms Symbol Conditions min typ max unit
NC effect
SN-NC
5
[Multipath Rejection Circuit] MRC input (pin 27) MRC output MRC operating level VMRC MRC-ON V24 = 5 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 2.2 10 2.3 15 2.4 20 V mVrms
[AM Characteristics] AM ANT input Practical sensitivity Detector output Pin 31 detector output AGC F.O.M. Signal-to-noise ratio Total harmonic distortion Signal meter output Oscillator buffer output Wide band AGC sensitivity S/N-30 VO-AM VO-AM31 VAGC-FOM S/N-AM THD-AM VSM AM-1 VSM AM-2 VOSCBUFF AM1 W-AGCsen1 W-AGCsen2 SD sensitivity IF buffer output SD-sen1 AM SD-sen2 AM VIFBUFF-AM 1 MHz, 30 dB, fm = 1 kHz, 30% modulation, pin 15 1 MHz, 74 dB, fm = 1 kHz, 30% modulation, pin 15 1 MHz, 74 dB, fm = 1 kHz, 30% modulation, pin 31 1 MHz, 74 dB, referenced to the output, the input amplitude such that the output falls by 10 dB. Pin 15 1 MHz, 74 dB, fm = 1 kHz, 30% modulation 1 MHz, 74 dB, fm = 1 kHz, 80% modulation No input 1 MHz, 130 dB, unmodulated No input, the pin 15 output 1.4 MHz, the input when V46 = 0.7 V 1.4 MHz, the input when V46 = 0.7 V (seek mode) 1 MHz, the ANT input level such that the IF counter output turns on. 1 MHz, the ANT input level such that the SD pin goes to the on state. 1 MHz, 74 dB, unmodulated. The pin 23 output 0.0 3.5 185 92 83 24 24 200 20 130 110 59 47 195 175 64 52 0.3 0.2 4.4 230 98 89 30 30 290 104 95 36 36 1 0.5 6.1 270 230 69 dB mVrms mVms dB dB % V V mVrms dB dB dB dB 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 k. * 2. When the resistor between pin 58 and ground is 30 k.
No. 6038-3/50
LA1781M 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. 6038-4/50
LA1781M 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) AC2 AC3 AC4 AC5 Used for noise canceler testing. A pulse generator and an AF oscillator are required. Used for FM front end testing. Outputs an 83 MHz signal. Used for FM IF, noise canceler, and MPX testing. Outputs a 10.7 MHz signal. Stereo modulation must be possible. Used for AM testing. Outputs 1 MHz and 1.4 MHz signals. Used with the MRC. Can also be used for AF and OSC.
Power supply
VCC VCC1 VCC2 VCC3 8V 5V 0.1 V / 0.7 V / 2 V / 4 V 0.1 V / 0.6 V / 2 V These levels must be variable. SD, stereo, seek/stop Keyed AGC, Mute ATT HCC, SNC, SASC (MRC)
* Switches
Parameter SW1 SW2 SW3 SW4 SW5 SW6 SW7 SW8 SW9 SW10 AM/FM switching. The FE VCC is supplied to pin 62. FM IF switching. Pin 51/FE output For conversion gain testing For switching between noise canceler input and IF output + noise canceler. High-speed SD SEEK/STOP (IF BUFF ON/OFF) MUTE ATT 200 k MUTE ATT 30 k For pilot cancellation testing Mute off (pin 33) ON FM FE IF OUT (A) Conversion gain measurement (A) AC1 (A) High-speed SD STOP MUTE 200 k MUTE 30 k When pilot cancellation is used MUTE OFF OFF AM AC3 (B) Other/purposes Other/purposes Other/purposes Seek (IF buffer output) OFF OFF When pilot cancellation is not used MUTE ON
* Trimmers (variable resistors)
VR1 VR2 Separation adjustment Pilot cancellation adjustment
Test Points * 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 MRC output Mute drive output AM antenna damping voltage N.C. Gate time Pin 2 Pin 26 Pin 24 Pin 27 Pin 33 Pin 46 Pin 8
* AC voltages
VA1 VA2 VA3 VA4 VA5 AM/FM OSC Buff First IF output IF counter buffer MPX OUT Left ch MPX OUT Right ch Pin 4 Pin 53 CF pin 51 load level (10.7 MHz) Pin 23 (10.7 MHz/450 kHz) Pin 15 (AF) Pin 16 (AF)
No. 6038-5/50
LA1781M Pin Descriptions
Pin No. Function Description Equivalent circuit
VCC ANT RF AGC 62 pin
1000 pF
1
Antenna damping drive
An antenna damping current flows when the RF AGC voltage (pin 2) reaches VCC - VD.
100 1 1000 pF
300
100
A11711
VCC
FET 2ND GATE
12 k 2 DAMPING DRIVER
2
RF AGC
Used to control the FET second gate.
+
ANT
N AGC DET KEYED AGC
W AGC DET VCC
A11712
3
F.E.GND
VCC
4
OSC
Oscillator connection The transistor and capacitors required for the oscillator circuit are integrated on the chip.
VT
4
25 pF 2 k 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.
ALC
A11714
Continued on next page.
No. 6038-6/50
LA1781M
Continued from preceding page. Pin No. Function Description Equivalent circuit
3 k 3 k 15 k
8 9
Noise AGC sensitivity AGC adjustment
After setting up the medium field (about 50 dB) sensitivity with the noise sensitivity setting pin (pin 8), set the weak field (about 20 to 30 dB) sensitivity with the AGC adjustment pin (pin 9)
8
200
9
3 k 0.01 F 1 M
+
0.47 F
A11715 A11715
0.01 F
6800 pF
3.9 k
13
12
VCC
11
11 12
Memory circuit connection
Recording circuit used during noise canceller operation.
Differential amp Gate circuit
LPF
A11716
VCC
30 k
PLL
13
Pilot input
Pin 13 is the PLL circuit input pin.
N.C 12 13
0.01 F
A11717
14
N.C, MPX, MRC, GND
Ground for the N.C., MPX, and MRC circuits. Continued on next page.
No. 6038-7/50
LA1781M
Continued from preceding page. Pin No. Function Description Equivalent circuit
VCC
15 16
MPX output (left) MPX output (right)
Deemphasis 50 s: 0.015 F 75 s: 0.022 F
3.3 k 3.3 k
15 0.015 F
16 0.015 F
A11718
VCC
20 k
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.
10 k
6.7 k
17 0.01 F 100 k
18
A11719 A11719
VCC
18
Pilot canceller signal output
Pin 18 is the output pin for the pilot canceller signal.
1.5 k
17 0.01 F 100 k
18
A11720
Continued on next page.
No. 6038-8/50
LA1781M
Continued from preceding page. Pin No. Function Description Equivalent circuit
DECODER 5 k
Composite signal
19
Separation adjustment pin
Use a trimmer to adjust the subdecoder input level. (The output level is not modified in mono and main modes.)
19 30 k 0.047 F
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
21 22
PHASE COMP. PHASE COMP.
+
15 k
15 k
19 k 21
+ +
22
A11723
Continued on next page.
No. 6038-9/50
LA1781M
Continued from preceding page. Pin No. Function Description Equivalent circuit
4.9 V
+ -
50 k
+ -
AM MUTE VCC IF counter buffer
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
1.3 V 10 k
SW
+ -
150 50F
SD circuit
23
51 k
STOP IF BUFF. Forced SEEK SD: 2.5 V 5 V
A11724
VCC
FM S-meter
24
AM/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 AM S-meter 10 k 10 k 24 AM/FM SW
32
Dedicated FM signal meter
Outputs a 1-mA current during AM reception
MRC
AM/FM SW
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 k VDD
A11726
Continued on next page.
No. 6038-10/50
LA1781M
Continued from preceding page. Pin No. Function Description
VCC 2 A VCC
Equivalent circuit
27
MRC control voltage time constant
The MRC detector time constant is determined by a 100 resistor and C2 when discharging and by the 2-A current and C2 when charging.
27 100
+
C2
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. It can also be controlled by the MRC output. Use a resistor of at least 100 k when controlling with the pin 32 FM S-meter signal.
32 29 1 F
+
29
HCC control input
A11729
Continued on next page.
No. 6038-11/50
LA1781M
Continued from preceding page. Pin No. Function Description
VCC FM detector output
Equivalent circuit
31
30
Noise canceller input
Pin 30 is the noise canceller input. The input impedance is 50 k. 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 k. To improve the low band separation, use a coupling capacitor of over 10 F.
VCC AM detector
10 k
1 F
+
31
AM/FM detector output
30 Noise canceller 50 k 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-k resistor to attenuate the MRC AC input and control the circuit.
10 k
+
1 F
1 k
MRC input
A11731
C1
+
0.1 F
*The muting time constant is determined by an external RC circuit as described below. Attack time: TA = 10 k x C1 Release time: TR = 50 k x C1 *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-k resistor.
33 VCC 50 k MUTE AMP. SEEK OFF 10 k
33
Mute drive output
SOFT MUTE
HOLE DET
Band muting
50 k SD circuit
A11732
Continued on next page.
No. 6038-12/50
LA1781M
Continued from preceding page. Pin No. Function Description
0.1 F V REF VCC C
Equivalent circuit
R1
37 VCC
R2
36
35
34
*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. 34 35 36 37 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. V37 = 4.9 V
Quadrature detector
HOLE DET
3 pF
390
1 k
IF limitter amplifier
Band muting
A11733
R
SD ADJ
38
38
FM SD ADJ
A 130-A current flows from pin 38 and, in conjunction with the external resistance R, determines the comparison voltage.
130 A
+ -
SD
Comparator 24 S-meter
A11734
S-meter 6.4 k 3.6 k
24
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 k 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 VCC
90 A
39
AM IF out
50 pF 150
A11735
Continued on next page.
No. 6038-13/50
LA1781M
Continued from preceding page. Pin No. Function Description Equivalent circuit
VCC 20 k
+
20 k
41
HCC capacitor
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. Note: The LC capacitor must be connected between this pin and VCC (pin 40). This is because the detector circuit operates referenced to VCC. The cutoff frequency fC is determined by the following formula. fC = 1/2 x 50 k x C
VCC
VCC C 42
42
AM L.C. pin
DET
50 k
1 k
+ -
50 k
1 k
A11737
VCC
19 kHz0 BIAS
30 k
43
Pilot detector
Inserting a 1-M resistor between pin 43 and VCC will force the IC to mono mode.
30 k
+
30 k
43 1 F
+
A11738
Continued on next page.
No. 6038-14/50
LA1781M
Continued from preceding page. Pin No. Function Description Equivalent circuit
VCC C 2.2 F
0.022 F
+
240 k 42 44
44
IF AGC
G1; Used for time constant switching during seeks. * Reception = 2.2 F x 300 k * Seek = 2.2 F x 10 The external capacitors are connected to VCC. This is because the IF amplifier operates referenced to VCC.
VCC DET
50 k
50 k IF AGC
G1
SEEK ON 10
A11739
Pin 40 VCC
45 Pin 40 VCC
45
IF output
The IF amplifier load
DET
A11740
VCC
50 pF 46 100
46
AM antenna damping drive output Wide band AGC input
I46 = 6 mA (maximum) This is the antenna damping current.
VCC
20 k
W.AGC AMP. ANT DAMPING DRIVER
A11741
Continued on next page.
No. 6038-15/50
LA1781M
Continued from preceding page. Pin No. Function Description Equivalent circuit
30 k R 47 VCC
47
FM muting on level adjustment
Modify the value of the external resistor to adjust the muting on level.
140 A
Pin 24
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.
48
+
3.3 F
For AGC use 57
+
47 F
A11743
2.6 V 10 k 50 0.022 F 330 51 10 k
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.
IF in
A11744
52
IF input
The input impedance is 2 k.
52
+ -
Inverter MUTE
A11742
10 k
+ -
Antenna damping
2 k
100
A11745
Continued on next page.
No. 6038-16/50
LA1781M
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 V56 = 2 V Input impedance: RIN = 330 V53 = 5.3 V Output impedance ROUT = 330
IF IN 56 2.75 V
300
300
A11746
Pin 40 VCC
Pin 40 VCC 54
54 49
Mixer output: 130 A Mixer input
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
49
OSC
330
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 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 A, and V55 varies depending on the value of the external resistor. The SD function operates by comparing V55 with the S-meter voltage.
55 C1 30 pF
58
50 pF
MIX IN
58 C2 50 A
MIX OUT
+ -
AM SD
Signal meter
A11748
Continued on next page.
No. 6038-17/50
LA1781M
Continued from preceding page. Pin No. Function Description
1ST.IF
Equivalent circuit
OSC
59
Double balanced mixer Pins 59 and 60 are the mixer 10.7-MHz output 59 60
60
VCC
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. Note:The lines for pins 63 and 64 must be kept separated from the lines for pins 59 and 60.
30
VCC C1 63 RF AMP 5 pF C2 64 5 pF 620 620
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
SD
+
VCC 6
510
+ -
AM/FM switching circuit
FM.F.E AGC 100 k 8V 3 GND
When 8 V FM OPEN AM
3.3 V
A11750
AM 1st MIX to RF Amp. 62
62
1st MIX INPUT
First mixer input The input impedance is about 10 k.
2.1 V
10 k
A11751
10 k
5.6 V
20 pF
to 2nd MIX
10
AM 2nd OSC
Crystal oscillator circuit The Kinseki, Ltd. HC-49/U-S and a CL of 20 pF must be used.
33 pF
10 X tal
A11752
No. 6038-18/50
LA1781M Block Diagram
VCC GND 6.8k KEYED AGC 30k FM SD ADJ. PILOT DET 0.47F
0.022F TO AM STEREO (IF OUT)
AM LC
+
0.22F
0.022F
2200pF
100F
10k VREF 0.47F
3.3F
IF7
1F
+
11k
2.2F
+
CHCC
0.022F
30 620
0.022F 1MH 100F
+
RFAGC 48
240k 47 46 ANT D 45 44 43 42
0.1F 40 39 38
10k
QD IN
AFC IN
+
+
QD OUT
+
41
37
36
35
34
MUTE DRIVE 1F 33 FM
1k
49 FC18 15pF 15pF 100H 100k 47F 30MH 0.022F
+
OSC OSC BUFF
100k 50k AM LEVEL ADJ
32 31 30 HOLE DET MUTE DRIVE DC-C AFC DET CLAMP IF BUFF MRC 29 28 27 26 HCC 25
METER DET OUT 1F
+
FM IF IN 0.022F 220
50 51
IF limiterlimiter IF amplifier
BUFF DET L.C. IF AGC AMVSM AM SD
Q.DET
amplifier
MUTE AMP
8200pF AM HC 1F
+
100 510k AM IF IN 52 53 54 AM SD ADJ AM MIX OUT 20k FM WB AGCIN FE IF IN 55 56 MIX + RF AGC WB AGC
NC-IN HCC SNC 1F
+
ANTD 0.022F
FM IF OUT
100k 5V
+
TWEET
IF AM/FM REG SW
SNC
10k
GND
FMVSM FM SD
GND AM/FM S-METER 0.47F
+
SEEKAM/FM SD STOPFM ST IND.
AM FM VREF 300 200k 0.022F 2k VCC 30 60 0.022F FEVCC MIX 61 AM/FM MUTE ATT 59 330 57 62pF 58 W.B.AGC RF AGC
SEEK SW SD/ST IND
VCO STOP MAIN HC AMP INPUT
FF 19k<90 k
PHASE COMP
24 23
KEYED AGC HPF
FF 19k<0
VCO 22 21 20
5.6k
+
0.22F * CSB912JF108 or KBR912F108
LPF
PILOT DET
TRIG
1F *
0.022F
VCC 100k 100F 30 1000pF 180 3SK263 100k 8pF 18pF
0.022F 62 63 5pF 64 30k 5pF
NOISE AMP BUFF BUFF AM 1ST OSC AGC TRIG
AMP PICAN INPUT GATE
P-CAN
-+
FF 38k<0 FF
0.047F 20k 19 SEP.ADJ 18 100k 17 0.01F PI.CAN ADJ
COUNTER
SUB MAT DEC RIX
22pF 22pF 1000pF 100k 39pF 9pF
ANT D ANT D RF AGC OSC 1 2 FE GND 3 4 5 6 7 10k 8 9 0.47F 10 11 12 13 AM OSC 6800pF 0.01F 14 N.C.MPX GND 15 16 MPX OUT 0.015F 0.015F
100k
1000pF
1F
30k
100 0.022F FM GND
+
10pF 5pF
GND
0.022F
GND
0.1F
30k
300pF 30k AM/FM OSC BUFF 0.022F 18pF 0.022F LEFT CH. 10.26MHz NC MPX GND RIGHT CH.
AM RF GND
AM ANT IN
FM ANT IN
FM/AM VT
AM VCC
FMIF AM GND
200k
0.01F 1M
18pF
+
FMIF AM NC MPX VCC
1000pF
FM/AM VSM
10F
+ +
10F
+
R L
10F
10F
240k
200k
2.2k
68pF
240k
+
22k
22k
100k
100k
10k
+
10k
2.2k
1F 10k
+
0.01F
3SK583
10F 1.5k
4.7k
1k
51k
0.22F
22k
+B 12V
0.22F 22pF 20 19 VSS 7.2MHz 18 PD 17
100pF 16
100pF 15
100pF 14
100pF 13 12
51k
100k
11
100F
+
VDD
FM IN
AM IN
5.6V
10k
100F
100k
10k
1 22pF
6
7
8
9
+
9.1V
100pF
CE
CI
CL
DO
RDS
1k
ADC MUTE SD/MONO ST
R ON
LC867148
22k
CE 2
CI 3
CL 4
DO 5
FM/AM 10
1k
LC7216M
22k
22k
A11753
No. 6038-19/50
LA1781M AC Characteristics Test Circuit
VCC GND 6.8k KEYED AGC 22k FM SD ADJ. PILOT DET 0.47F 8V VCC
AM LC
+
0.22F
0.022F
3.3F
VREF
2.2F
IF7
1F
+
15k
50
+
300
0.1F
50
CHCC
RFAGC 48
240k 47 46 ANT D 45 44 43 42
0.1F 40 39 38
10k
QD IN
AC3 SG3
AFC IN
+
+
QD OUT
B SW2 ( i ) MIX A
IF IN
SW3
2200pF
VA2
100F
0.022F
IF OUT
MUTE OR ADJ
10k 4.3k VD5
+
+
41
37
36
35
34
MUTE DRIVE 33 FM S-METER DET OUT
+
MRC-IN
VCC2
1F
+
300 200
330
FM IF IN 50 51 52 53 54
AM LEVEL ADJ 8200pF AM HC B SW4 (T) A
+
+
49
OSC OSC BUFF MUTE AMP
32 31 30 HOLE DET MUTE DRIVE DC-C AFC DET CIAMP IF BUFF 27 29 28
AC5
1F
IF limiter amplifier BUFF DET L.C. IF AGC AMVSM AM SD FMVSM FM SD
Q.DET
30 0.022F
NC-IN PG1 (AC1) HCC 100k 100k SNC
0.022F AM IF IN
NC-IN HCC SNC 1F
+
0.022F 620 1MH
FM IF OUT 100H AM SD ADJ AM MIX OUT FM WB AGCIN 20k 100k 47F
+
VCC3
MIX 55 56 57
+ 100k RF AGC W.B. AGC TWEET MRC 26 25 FF 19<90 k 24 23 FF 19<0 FF FM/AM REG SW
-+
VD4 VD2 GND AM/FM S-METER 0.47F
+
FC18 50 30 15pF 65pF JIS DUMMY ANTD 0.022F 300k 200k 30k
+
100H 0.022F 6.8MH
FE IF IN
0.022F
AC2 SG2
SEEKAM/FM SD STOPAM ST BUFFER FM ST IND.
50k
330
510
10pF 58 W.B.AGC RF AGC
SNC AM FM VREF KEYED AGC HPF LPF HCC
PHASE COMP
VA3 5.6k
+ +
1k 0.022F 30
MUTE ATT
VCO 22 21 20
FM/AM IFBUFF. 50k 0.22F SW5 SW6 VD3 8V 0.022F 10k VA8 VCC2
5V VCC1
59 60
VD6 VCC SW7
VCO STOP PILOT DET TRIG
FEVCC VCC
MIX 61 AM/FM 62 BUFF BUFF AM 1ST OSC AGC 64 ANT D 1 ANT D 2 RF AGC FE GND 3 4 OSC 20pF 0.022F 5pF 5 6 7 8 0.01F 10k 1M 9 0.47F 10 11 12 13 AM OSC + 6800pF 0.01F 14 TRIG GATE
1F CSB912JF108
P-CAN FF 38k<0 MAIN HC FF 19 18 17
SW8
0.047F 20k SEP.ADJ VR1 SW9 100k VR2 0.01F PI.CAN ADJ 3pF 1M
50
+
25 1000F
3pF 39pF 63 5pF 5pF
AC1 SG1
50
SUB MA DEC TRIX
100k
VD1 100 100 0.022F 0.022F
N.C.MPX GND
15 16 MPX OUT 0.015F 0.015F RIGHT CH.
1F
30k
+
300pF
GND
20k AM/FM OSC BUFF 0.022F
10k
1M
SW1 10F
+
10k
10k
VT
10F
+
8V
VA6 VA9
VA7
A11754
VA1
LEFT CH.
FM GND
FM VCC
SW10 10.26MHz X TAL VCC
3pF
8V 0.022F VCC
No. 6038-20/50
LA1781M Test Conditions
Parameter Current drain Demodulation output Pin 31 demodulation output Channel balance Total harmonic distortion (FM) Signal-to-noise ratio: IF AM suppression ratio: IF Symbol ICCO-FM VO-FM VO-FM31 CB THD-FMmono S/N-FM IF AMR IF Att-1 Muting attenuation Att-2 Att-3 Separation Stereo on level Stereo off level Main total harmonic distortion Pilot cancellation SNC output attenuation HCC output attenuation 1 HCC output attenuation 2 Input limiting voltage Muting sensitivity SD sensitivity 1 SD sensitivity 2 IF counter buffer output Separation ST-ON ST-OFF THD-Main L PCAN AttSNC AttHCC-1 AttHCC-2 Vi-lim Vi-mute SD-sen1 FM SD-sen2 FM VIFBUFF-FM VSM FM-1 Signal meter output (FM) VSM FM-2 VSM FM-3 VSM FM-4 Muting bandwidth Mute drive output N-AGC on input W-AGC on input Conversion gain Oscillator buffer output Gate time 1 Noise sensitivity NC effect MRC output MRC operating level Practical sensitivity Detection output Pin 31 detection output AGC F.O.M. Signal-to-noise ratio Total harmonic distortion (AM) Signal meter output (AM) Oscillator buffer output Wide band AGC sensitivity BW-mute VMUTE-100 VNAGC VWAGC A.V VOSCBUFFFM GATE1 SN SN-NC VMRC MRC-ON S/N-30 VO-AM VO-AM31 VAGC-FOM S/N-AM THD-AM VSM AM-1 VSM AM-2 VOSCBUFF AM-1 W-AGCsen 1 W-AGCsen 2 SD-sen1 AM SD-sen2 AM VIFBUFF-AM Switch states SW1 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 ON ON ON ON ON ON ON ON ON ON/OFF ON ON OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF SW2 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 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 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 ON ON ON OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF OFF SW4 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 SW5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- OFF ON OFF -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- ON ON ON ON ON ON ON ON ON ON ON OFF OFF OFF 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 ON ON ON ON ON ON ON ON ON ON ON ON ON ON OFF/ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SW10 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- ON -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
SD sensitivity IF buffer output
No. 6038-21/50
LA1781M Usage Notes 1. Notes on VCC and Ground
Pin 40 Pin 25 Pin 14 Pin 61 * Pin 6 Pin 3 VCC for the FM IF, AM, NC, MPX, and MRC blocks Ground for the FM IF and AM blocks Ground for the NC, MPX, and MRC blocks VCC for the FM front end, AM first mixer, and first oscillator blocks VCC for the FM front end and AGC blocks, and the AM/FM switching pin 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 8 OPEN
Mode 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. f -- AGC Sensitivity
When f = 0, 98.1 MHz
110
AGC sensitivity -- dB
100
90
The wide AGC sensitivity when pin 39 is 5 V.
80
70
60
The narrow AGC sensitivity when pin 39 is at ground.
-5 -4 -3 -2 -1 0 1 2 3 4 5
50
f -- MHz Fig. 2
No. 6038-22/50
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 Only the narrow AGC sensitivity (operation at f < 1.5 MHz) is controlled by the field strength of the desired station. The narrow AGC sensitivity is controlled by a voltage (V 23) that is under 0.5 V. Merit * Effective in resolving second-channel attenuation problems. * Allows effective resolution of second-channel attenuation problems without degrading three-signal characteristics. * 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. * Settings can be optimized for the field conditions. * 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.
The wide AGC can operate even when V23 = 0 (when the desired station is not present).
The narrow and wide AGC sensitivities can be set independently. (See figure 3 and 4.) The system has two AGC systems: narrow and wide AGC. (See figure 5.)
f -- AGC on Level (ANT input)
110
Fig.3
f -- AGC on Level (ANT input) Fig.4
Pin 55 capacitor: 3 pF
110
Narrow AGC on level -- dB
Wide AGC on level -- dB
100
100
90
90
80
Pin 58 capacitor: 10 pF keyed AGC 39 Pin 58 capacitor: 47 pF
-5 -4 -3 -2 -1 0 1 2 3 4 5
Pin 55 capacitor: 10 pF
80
70
70
keyed AGC 39 5V
-5 -4 -3 -2 -1 0 1 2 3 4 5
60
60
50
50
f -- MHz
f -- MHz Fig.5
Pin 59 narrow AGC and pin 55 wide AGC input levels -- dB
W-AGC, N-AGC -- f
70 80
Wide AGC on level frequency characteristic
90
s
Narrow AGC on
level frequency
characteristics
100
110
120
130
140 7 1.0
AGC input level frequency characteristics such that VRFAGC (pin 2) falls under 2 V.
2 3 5 7 10 2 3 5 7 100 2 3 5
Frequency, f -- MHz No. 6038-23/50
LA1781M 3D AGC Sensitivity Characteristics
AGC sensitivity Wide AGC sensitivity
F 1
2 Second-channel attenuation improvement 3 Desired station AGC sensitivity Narrow 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. f -- AGC on Level (ANT input)
The fu input level at which antenna damping turns on -- dB
110
fD = 98.1 MHz Second-channel pad
100
90
80
ANT IN VIN
70
60
fu = 98.1 MHz + f
A12076
50
-5
-4
-3
-2
-1
0
1
2
3
4
5
f -- MHz
Fig. 7
No. 6038-24/50
LA1781M 7. Notes on 3D AGC (Keyed AGC)
VCC
55
W-AGC DET
58
N-AGC DET 90A 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. 6038-25/50
LA1781M * The LA1781M 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
9 8 7
Fig.9
fr = 98.0 Hz VCC = 8 V Ta = 25C
V2AGC -- V
6 5 4 3 2 1 0 -10
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
0
10 20 30 40 50 60 70 80 90 100 110 120 130 140
ANT IN -- dB
MIX INPUT
MIX OUT
MIX OUT
MIX INPUT
Due to optimized device geometry, emitter current, the bias, this IC achieves the following performance. Mixer input usable sensitivity: 15 dB Mixer input IMQS: 90.5 dB (For an oscillator level of 200 mVrms)
OSC
MIX
* 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 Fig. 10
A12077
No. 6038-26/50
MIX VCC
* 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
64
59
60
63
62
LA1781M * 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 5 VT 20pF AM/FM OSC BUFFER OUT
A12078
Fig. 11
* Figure 12 shows the type of FM first IF amplifier used in this IC. It is a differential single-stage amplifier.
330 TO MIX FM IF input
56
53 330
+ 330 -
A12079
Fig. 12
Specifications Input impedance: 330 Output impedance: 330 Gain: 20 dB
No. 6038-27/50
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.
4.9V
R R
+ -
+ -
Band muting HOLE CLET Muting drive output
R
STEREO IND
S-meter
+ -
IF count buffer FM IF 33 23 26 5V IF count output SD STEREO/MONO 2.5V 5V
39
24
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 V38 V33 Smaller values of R33 Larger values of R33 S-meter
V33 over 0.7 V V26 5V On as an SD signal V23AC SD ON
V33 over 0.7 V
SD ON
Mono Stereo 0.7 V
OFF V23DC
IF count buffer 5V
OFF
IF counter output off
2.5 V
0V
RDS and other types of SD detection can be used by switching these modes. New LA1781M 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. 6038-28/50
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 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 10k Attack 33 C33 50k Release Mute amp
Muting time constants Attack: 10 k x C33 Release: 50 k x C33
A11766
Fig. 16
SD Sensitivity Adjustment
Antenna input such that pin 5 goes high -- dB
50
Fig.17
40
30
20
10
0 6
10
14
18
22
26
30
34
Resistance between the pin and ground -- k No. 6038-29/50
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.
F.E.
IF
IF buffer amp
5V
0.022 F
Test system capacitance The 10.7 MHz feeds back through ground.
Fig. 18
A12081
* FM Muting control pin (pin 47) (R47: 30 k variable resistor) The -3 dB limiting sensitivity can be adjusted with R47.
FM Soft Muting (1)
R47 = 7.5 k 15 k
Fig.19
DET out
Output, noise -- dB Output
10 k
20 k
Noise
Antenna input -- dB
* 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
R58 Open Mute ATT -20 dB -30 dB -40 dB
100
R58
200 k 30 k
A11764
The attenuation can be set by making R33 smaller as listed in the table above.
33
R33
A11765
Fig. 20 No. 6038-30/50
LA1781M
FM Soft Muting (2)
R47 = 7.5 k
Fig.21
DET out
FM Soft Muting (3)
R47 = 7.5 k
Fig.22
DET out
10 k
Output, noise -- dB Output noise -- dB Output -- dB
10 k 15 k
Output -- dB
15 k
200 k
30 k
20 k
Noi
se
2 0k
Nois
e
Antenna input -- dB
VCC Quadrature detector 200 k R
+ -
Antenna input -- dB
Mute amp. (VCA)
R
+
N-AGC
-
Mute drive R
Limiter
58
33
31
DET out To MIX out
Open 200 k 30 k
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 dB.
20
Antenna input
A12082
Fig. 24 No. 6038-31/50
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 5 dB. The amount of attenuation is referenced to an antenna input of 60 dB, 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 dB inputs can be set independently. Hall Detection Output -- Antenna Input Characteristics Fig.25
5
Area muted by Hall detection
4
V38pin -- V
3
2
1
0 -20
-10
0
10
20
30
Antenna input -- dB
(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 dB.
36
33 Vb
+
Va
0.1F
0
0
A12083
Fig. 26
(3) Unique features One unique feature of the LA1781M 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. 6038-32/50
LA1781M
Voltage between pins 37 and 34, VAFC -- V Pin 33, VMute -- V Voltage between pins 37 and 34, VAFC -- V Pin 33, VMute -- V
Unique Features of the LA1781M Hall Detection Circuit (1)
2 1
Fig.27
ANT IN
Unique Features of the LA1781M Hall Detection Circuit (2)
2 1
Fig.28
When the tuner is moved in 50 kHz steps. With a 51 k resistor between pins 37 and 34. With the SD sensitivity adjusted to be 20 dB.
f1 f2
When the tuner is moved in 50 kHz steps. With a 51 k resistor between pins 37 and 34. With the SD sensitivity adjusted to be 20 dB.
0
0
-1
-1
6
6
4
4
2
2
0
0
Pin 24, VSM -- V
4
Pin 24, VSM -- V
6
6
4
2
2
0
8
Pin 26 (SD) -- V
6
Pin 26 (SD) -- V
f2 = 97.9 MHz, 120 dB fm = 400 Hz, 22.5 kHz dev. f1 = 98.1 MHz, 120 dB fm = 1 kHz, 22. 5kHz dev.
0
8
6
f2 = 97.9 MHz, 40 dB fm = 400 Hz, 22.5 kHz dev. f1 = 98.1 MHz, 40 dB fm = 1 kHz, 22.5 kHz dev.
4
4
2 0 97.7
2 0 97.7
97.8
97.9
98.0
98.1
98.2
98.3
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 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 k 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
6
Fig.29
SA208 + LA1781M IF Input Characteristics
4 0.8 3 0.6 2 0.4
Fig.30
With pins 34 and 37 shorted. With 5 V applied to pin 24.
5
Vmute -- V
THD -- %
4
1 0.2 -100 -80 -60 -40 -20 -120 0 -0.2 -0.4 20 40
THD 1 kHz 75 kHz dev f -- kHz
60 80 100 120
3
2 SG 1
75 0.022 F
75
+
With the resistor between pins 36 and 37 open. With a 10 k resistor between pins 36 and 37.
f=0 10.7 MHz
10.7 MHz 0 92 94 96
36 98
37
LA1888M 100 102 104 106
-0.6 Voltage between pins 37 and 34 -0.8 (referenced to the pin 37 voltage)
QD input level -- dB No. 6038-33/50
LA1781M
Detector output Pin 36 AC level MPX OUT Vo QDIN 330 mVrms 280 mVrms 235 mVrms 200 mVrms
R36-37 Open 10 k
* Band Muting Adjustment Procedure The muting bandwidth can be modified as shown in figure 31 with the resistor RBW between pin 34 and 37. RBW -- Muting Bandwidth
Bandwidth such that the pin 33 voltage 2 V -- kHz
280 RBW 240
+ +
Fig.31
1 F
0.47 F
200 10 k 160 37 36 35
SA208 Sumida
34
ANT IN 98 MHz 100 dB
120
80
40 0 1.0
2
3
5
7
10
2
3
5
7 100
2
Resistor RBW between pins 34 and 37 -- k
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.
RW 1st MIX 10.7MHz CF RF 62 49 2nd MIX 450kHz CF 52 IF Amp. DET 31 VCC 42 1st OSC X'tal 240 k VCC 46 Middle AGC IN Narrow AGC IN Wide AGC IN ANT damping 57 + 47 F RF AGC Amp. IF AGC 44 2.2 F
48 + 3.3 F
Fig. 32
A11762
No. 6038-34/50
LA1781M AM AGC f characteristics
Wide AGC Operates for wide band interference
100
Fig.33
90
Wide AGC Operates for wide band interference
80
AGC on level
Middle AGC Operates for interference within 70 kHz of the received frequency.
Middle AGC Operates for interference within 70 kHz of the received frequency.
70
Narrow AGC Operates at the received frequency.
800
900
60 1000
1100
1200
Frequency -- Hz
Wide Band AGC Circuit
120
Fig.34
Antenna damping on input level -- dB
30 110 -6dB SG 100 ANTD 0.022 F 90
0.022 F 50 50 46 0.022 F
Received frequency: 1 MHz
510
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 F VCC
30 620 1MH 100 H FC18 57 47 F 15 pF 15 pF
+
100 H 0.022 F 100 k 30MH
62 Fig. 35
A12084
No. 6038-35/50
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 5 V reference voltage as shown in figure 36.
S-meter
VCC
Comparator
+ -
AM IF
IF buff amp. 50 pF
50 A
55 100 k
24 0.47 F
23
26 100 k
51 k
0.022 F
5V
IF buffer Seek 5V Fig. 36
SD
A12085
Figure 37 shows the relationship between the AM SD, the IF count buffer, and the S-meter.
V24PIN V55 V26 Smaller values of R55 Larger values of R55 S-meter
SD on V23AC OFF V23DC 5V Pin 55: AM SD adjustment pin 0V
A11760
IF buffer on
AM SD Sensitivity Adjustment
Antenna input such that pin 26 becomes 5 V -- dB
80 70 60 50 40 30 20 10 0 0
Fig.38
10
20
30
40
50
Resistance between pin 55 and ground -- k
No. 6038-36/50
LA1781M * AM high band cut and detector output level adjustment methods The pin 31 AM and FM tuner output has an impedance of 10 k 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 k
+
Noise canceler input
30 50 k
A12086
Fig. 39
* AM stereo system pins
To the AM stereo decoder VCC IFT 45 39 GND 400 mV rms 450 kHz output
VCC
50 pF 150 Keyed AGC
IF AMP. Fig. 40
A11761
No. 6038-37/50
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 VCC. Since the detector is designed with VCC as the reference, C42 must be connected to VCC. Detector Output -- Frequency
20
Fig.42
VCC
10
0.1 F Detector output -- dB
C42
0
80%mod With no C31 used.
42 50 k AM detector 50 k 10 k
A12087
10 k
+ -
-10
10 k To pin 31
-20
30%mod 0.022 F C31pin 0.047 F = 6800 pF 0.1 F C42pin= Using SEP 450H
-30
Fig. 41
-40
-50 3
fr = 100 kHz fm = 10 kHz 30%mod
5 70.01 23 5 7 0.1 23 5 7 1.0 23 5 7 10 2
Frequency -- Hz
7. Noise Canceler Block * The noise canceler input (pin 30) has an input impedance of about 50 k. 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 F 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 dB) with pin 8 (the noise sensitivity setting pin), and then set the AGC level for a weak field (20 to 30 dB) 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 dB, the ceramic filters are 150 kHz x 1 and 180 kHz x 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 k 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.
H1 W1 2.5OU IF audio output f = 10 kHz,180 kHz dev
IF output 31
+
1 k
Noise canceler input
-
30
2200 pF
1 F
A12089
Fig. 44
-2.5OU -19.00 s Fig. 43
981.00 s
A12088
No. 6038-38/50
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.
20 k To the matrix 41 C VO (dB)
Fig. 45
A12090
1 fC = -------------- [Hz] 2 x C x 20 k Frequency Characteristics
10 0
1 2C x 20 k Fig. 46
f (Hz)
A12091
Fig.47
Changes in the pin 41 capacitor capacitance (for a 100% high cut ratio) 0.001 F
0 F
Attenuation, HCC -- dB
-10
0.0022 F
-20
0.0047 F
0.0
-30
F 1
-40
-50 -60 3
VCC = 8.0 V f = 98 MHz 100%mod 80 dB 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 k 0.01 F 50 k
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. 6038-39/50
LA1781M * Separation adjustment (pin 19)
5 k 19
A12094
To the subdecoder
Larger
20 k 0.047 F 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 A 100 DC buffer MRC 6.4 k 3.6 k 24
+
S-meter
FM S-meter
QMRC
30 k 10 k 75 pF 1 k 32
Noise amplifier High-pass filter with Fc = 70 kHz + amplifier
27
+
C27
VCC
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.
To the SNC, pin 28
A11768
Fig. 50
No. 6038-40/50
LA1781M (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 A * C27 2 A * C27 Release: 500 * C27 100 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.
A11771
A11772
Fig. 52
Fig. 53
No. 6038-41/50
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: 26C 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 dB MIX IN: 30 dB 1st IF IN: 42 dB 2nd IF IN: 60 dB 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
FM MIX IN 64 pin 1st IF IN 56 pin
RF
ANT IN
2nd IF IN 51 pin
11 dB
12 dB Fig. 54
18 dB
A11773
No. 6038-42/50
LA1781M (AM) This section investigates the gain in each block in the LA1781M when the Sanyo recommended circuits are used. (Test conditions) Ambient temperature: 26C 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 RF
1st IF
2nd MIX
2nd IF
AM DET
RF Gain
1st MIX Gain
1st IF Gain Fig. 55
2nd MIX Gain
2nd IF Gain
A11774
No. 6038-43/50
LA1781M Input Circuits for Each Stage [FM] * Mixer input
0.022 F 63 75 64 75 75 300 0.022 F 56
* First IF input
75
VIN Actual measurement fr = 10.7 MHz
A11775 A11776
* IF input
75 300 0.022 F 51 330 50 0.022 F fr = 10.7 MHz
A11777
75
[AM] * First mixer input
50 0.022 F 62 50
* Second mixer input
50 0.022 F 49 50
fr = RF
A11778
fr = 10.71 MHz (f2nd osc + 0.45 MHz)
A11779
* IF input
50 0.022 F 52 50
* Del input
50 0.022 F 45 50
IFT
fr = 450 kHz
A11780
fr = 450 kHz
A11781
No. 6038-44/50
LA1781M Sample AM tuner Circuit with the LC72144 Used Together
2nd MIX RF 1st IF CF CF 450K CF
IF
300
XBUFF
LC72144
fosc
A11782
AM 1st IF 1 2 fOSC 10.25 MHz fOSC 10.35 MHz 10.7 MHz 10.8 MHz
Step 10 kHz, 11 kHz 9 kHz, 10 kHz
FM IF 10.7 MHz 10.8 MHz
RF 62
1st MIX 10.71 MHz CF 59 60 1st OSC 56 53
IF CF 49 54 CF 52 10 k AF
2nd OSC 31 10.26 MHz NC MPX Lch Rch
10.7 MHz RF 63 64 60 59
IF CF 56 53 CF 51 Quadrature detector AF
A11783
No. 6038-45/50
LA1781M 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 (SA-1051)
1 2 3
AM OSC (SA-359)
S
3 2 4
6
4
1
6
AM IF1 (SA-264)
3 4
AM IF2 (SA-1063)
3 2 4
S2
1 6
1
6
S
S
S
AM loading (SA-1062)
3 2 1 6 4
AM ANT IN (SA-1048)
3 2 1 6 4
S
S
AM RF amplifier (RC875-222J)
0.1o2UEW
[FM Block] FM RF (SA-1060)
S
3 2 1 6 4 3 2 1 6 4
FM ANT (SA-1061)
S
S
FM OSC (SA-1052)
3 2 1 6 4
FM MIX (SA-266)
S
3 2 C1 4
8 7
1 C2 6
S
S
FM DET (SA-208)
S
3 2 1 6
S
4
No. 6038-46/50
LA1781M The Toko Electric Corporation [AM Block] AM FILTEER (A286LBIS-15327)
1 2 3 2 1 6 4 6 0.1o2UEW
AM OSC (V666SNS-213BY)
3 4
AM IF1 (7PSGTC-5001A=S)
3 2 1 6 0.05o3UEW 4
AM IF2 (7PSGTC-5002Y=S)
3 2 1 6 0.05o3UEW 4
AM loading (269ANS-0720Z)
3 2 1 6 0.05o3UEW 4
AM ANT IN (385BNS-027Z)
3 2 1 6 0.06o3UEW 4
AM RF amplifier (187LY-222)
0.1o2UEW
[FM Block] FM RF (V666SNS-208AQ)
S3
2 4 3 4
FM ANT (V666SNS-209BS)
o0.1-2UEW
1 6S
2
o0.1-2UEW
1 6S
FM OSC (V666SNS-205APZ)
3 2 1 4
FM MIX (371DH-1108FYH)
S3
2 4 5
o0.07-2UEW o0.12-2UEW 6S
1 6S
FM DET (DM6000DEAS-8407GLF)
3 2 1 6 0.07o2MUEW 4
No. 6038-47/50
Mixer output -- dB Output, noise, AM output -- dB Total harmonic distortion, THD -- % Output, noise, AM output, LR output -- dB
Input -- dB
Antenna input -- dB
Mixer input -- dB Antenna input -- dB DCV -- V Output, noise -- dB Antenna input -- dB Antenna input -- dB
LA1781M
First IF output -- dB
HCC, SNC, RF AGC, muting voltage, S-meter voltage, VSM -- V
Input -- dB
First IF input -- dB
No. 6038-48/50
LA1781M
First IF output -- dB
Frequency, -- MHz
First IF output -- dB
Frequency, -- MHz
S/N, AM output -- dB AGC on, separation, input level -- dB
Antenna input -- dB
Ambient temperature, Ta -- C
20
Ambient temperature, Ta -- C
AM I/O Characteristics
VCC = 8.5 V f = 1 MHz mod = 1 k 30% OUT
0
Separation, Sep -- dB
Output, noise -- dB
-20
-40
NOISE
-60
-80
-100 -20
0
20
40
60
80
100
120
140
Ambient temperature, Ta -- C
ANT input, IN -- dB
AM DC Characteristics
7.0
AM Distortion
7.0
RF AGC
6.0
Total harmonic distortion, THD -- %
VCC = 8.5 V f = 1 MHz
6.0
VCC = 8.5 V f = 1 MHz mod = 1 k 30% 80%
AGC, S-meter voltage -- V
5.0
5.0
4.0
4.0
3.0
3.0
2.0
VS
M
2.0
1.0
1.0
0 -20
0
20
40
60
80
100
120
140
0 -20
fm = 1 kH
0
20
40
fm = 1 kH
60
IF AGC
z 80%
z 30%
80
100
120
140
ANT input, IN -- dB
ANT input, IN -- dB
No. 6038-49/50
LA1781M
20
AM Second-Channel Interference Rejection Characteristics
100 dB
40 kHz
20
AM Second-Channel Interference Rejection Characteristics
400kHz desire mod ON
40 d
0
desire mod ON
40 dB
0
100 dB
B
Output, noise -- dB
Output, noise -- dB
60 dB
80 dB
60 dB
80 dB
-20
-20
-40
40 dB desire mod 60 dB OFF
fD=1MHz fm=1kHz 30%
dB 80
80
dB
100 dB
50/3 15pF ANT IN 50/3
-40
desire mod OFF
60 dB
50/3 50 50/3 15pF ANT IN
-60
50
-80 40
60
80
30 50 50/3 VIN 65pF fu=1040kHz fm=400Hz 30% JIS ANT. DUMMY 100 120 140
-60
fD = 1 MHz fm = 1 kHz 30%
-80 40
60
80
30 50 50/3 VIN 65pF fu = 1400 kHz fm = 400 Hz 30% JIS ANT. DUMMY 100 120 140
ANT input, IN -- dB
ANT input, IN -- dB
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 March, 2001. Specifications and information herein are subject to change without notice. PS No. 6038-50/50
10
0d
B
40 dB

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