Overview
The LA1837 is a single-chip AM/FM IF and MPX IC that
supports electronic tuning and was developed for use in
home stereo systems. It is optimal for use in automatic
station selection systems that use the SD and IF counting
techniques.
Functions
AM: RF
amplifier, mixer, oscillator, IF amplifier,
detector AGC, oscillator buffer, S-meter, narrow-
band SD, IF buffer
FM IF: IF amplifier, quadrature detector, S-meter, S-
curve detector, IF buffer output
MPX:
PLL stereo decoder, stereo display, forced mono,
VCO stop, post amplifier, audio muting, adjacent
channel interference rejection function
Features
On-chip MPX VCO (no external components required)
Adjacent channel interference rejection function
(third and fifth order)
Supports both the SD and the IF counting techniques.
The AM and FM SD sensitivities can be set independently.
The AM and FM output levels can be set independently.
Improved AM practical sensitivity and high-input
distortion characteristics
Package Dimensions
unit: mm
3061-DIP30S
Monolithic Linear IC
Ordering number : EN5688
82097HA(OT) No. 5688-1/9
SANYO: DIP30S
[LA1837]
SANYO Electric Co.,Ltd. Semiconductor Bussiness Headquarters
TOKYO OFFICE Tokyo Bldg., 1-10, 1 Chome, Ueno, Taito-ku, TOKYO, 110 JAPAN
Single-Chip Home Stereo IC with
Electronic Tuning Support
LA1837
Parameter
Symbol
Conditions
Ratings
Unit
Maximum supply voltage
V
CC
max
12
V
Allowable power dissipation
Pd max
Ta
70C
550
mW
Operating temperature
Topr
20 to + 70
C
Storage temperature
Tstg
40 to +125
C
Specifications
Maximum Ratings
at Ta = 25C
Parameter
Symbol
Conditions
Ratings
Unit
Recommended supply voltage
V
CC
9
V
Operating voltage range
V
CC
op
7 to 11
V
Operating Conditions
at Ta = 25C
No. 5688-2/9
LA1837
Parameter
Symbol
Conditions
Ratings
Unit
min
typ
max
[FM Mono Characteristics] fc = 10.7 MHz, fm = 1 kHz, with the coil adjusted so that V
AFC
V
REG
= 0 V
Current drain
I
CCO
-FM
With no input
18
31
44
mA
Demodulation output
V
O
FM
100 dB, 100% mod. The pin 16 output
730
1100
1460
mVrms
Channel balance
C.B-mono
100 dB, 100% mod. The pin 16 output/pin 17 output
1.5
0
+1.5
dB
Total harmonic distortion (mono)
THD
FM(1)
100 dB, 100% mod. The pin 16 output
0.3
1.3
%
Total harmonic distortion (mono)
THD
FM(2)
100 dB, 200% mod. The pin 16 output
1.0
5
%
Signal-to-noise ratio
S/N
FM
100 dB, 100% mod. The pin 16 output
72
80
dB
AM rejection ratio
AMR
100 dB, AM 30 % mod. The pin 16 output
45
65
dB
Limiting input voltage
3 dBL.S.
100 dB, 100% mod. Referenced to the output.
26
32
38
dB
The input such that the output is down 3 dB.
LED sensitivity
SD
On-FM
51
60
69
dB
LED bandwidth
SD
BW
100 dB
85
120
170
kHz
IF count buffer output
V
IFBuff-FM
100 dB. The pin 13 output
80
120
160
mVrms
S-meter output
V
SM-FM(1)
0 dB. The pin 11 output
0
0.1
0.5
V
V
SM-FM(2)
100 dB. The pin 11 output
3.6
4.3
5.0
V
Muting attenuation
Mute-Att
100 dB, 100% mod. The pin 16 output
75
85
dB
[FM Stereo Characteristics] fc = 10.7 MHz, 100 dB, fm = 1 kHz, L + R = 90%, Pilot = 10%
Separation (left)
Sep
L
L mod. The pin 16 output/pin 17 output
30
45
dB
Separation (right)
Sep
R
R mod. The pin 17 output/pin 16 output
30
45
dB
Stereo on level
ST
ON
The pilot modulation such that V7 is under 0.7 V.
1.3
2.7
5
%
Stereo off level
ST
OFF
The pilot modulation such that V7 is over 4.5 V.
1.5
%
Total harmonic distortion (main)
THD-main
L+R mod. The pin 16 output
0.3
1.3
%
Brej-3rd
fs = 113 kHz, Vs = 90 %, Pilot = 10 %, The pin
40
dB
Adjacent channel interference
16 output vs. the L-R mod. 1 kHz demodulated output
rejection ratio
Brej-5th
fs = 189 kHz, Vs = 90 %, Pilot = 10 %, The pin
40
dB
16 output vs. the L-R mod. 1 kHz demodulated output
[AM Characteristics] fc = 1000 kHz, fm = 1 kHz
Current drain
I
CCO-AM
With no input
15
25
35
mA
Detector output
V
OAM(1)
23 dB, 30% mod. The pin 16 output
100
180
360
mVrms
V
OAM(2)
80 dB, 30% mod. The pin 16 output
200
320
500
mVrms
Signal-to-noise ratio
S/N
AM(1)
23 dB, 30% mod. The pin 16 output
18
22
dB
S/N
AM(2)
80 dB, 30% mod. The pin 16 output
49
55
dB
Total harmonic distortion (mono)
THD
AM(1)
80 dB, 30% mod. The pin 16 output
0.4
1.2
%
THD
AM(2)
80 dB, 80% mod. The pin 16 output
1.0
4.0
%
LED sensitivity
SD
On-AM
17
27
37
dB
Local oscillator buffer output
V
OSC-AM
With no input. The pin 30 output
110
160
220
mVrms
IF counter buffer output
V
IFBuff-AM
80 dB, no modulation. The pin 13 output
160
220
300
mVrms
ST-IF output
V
STIF-AM
80 dB, no modulation. The pin 7 output
16
34
48
mVrms
S-meter output
V
SM-AM
0 dB, no modulation.
0
0
0.2
V
Electrical Characteristics
at Ta = 25C, V
CC
= 9 V, in the specified Test Circuit
Allowable power dissipation, Pd max mW
Ambient temperature, Ta C
Pd max Ta
Block Diagram
No. 5688-3/9
LA1837
Test Circuit Diagram
FM SD
ADJ
3 rd 5 th
DECODER
ANTI-BIRDIE
FM
Pin No.
Pin function
Pin voltage (V)
Pin description
Equivalent circuit
Coil Specifications
No. 5688-4/9
LA1837
AM oscillator (for the DUT)
HW-50425 (Mitsumi Electric Co., Ltd.)
IFT
YD-1073-1 (Mitsumi Electric Co., Ltd.)
FM detector
600BEAS-9715Z (The Toko Electric Corporation)
Pin Functions
1
FM IF input
Vreg
2
AM mixer output
V
CC
Input impedance ri = 330
Connect the mixer coil between this pin and
V
CC
.
3
FM IF input bypass
Vreg
Also functions as the MPX regulator filter.
4
5
6
7
8
9
AM IF input
GND
TU - LED
ST - LED
AM-IF output
V
CC
FM detector
Vreg
0 V
V
CC
V
CC
V
CC
V
CC
Input impedance ri = 2 k
Active low
Open collector output
AM stereo IF output (pin 7)
The current input must not exceed 150 A.
Recommended detector coil: 600BEAS-
9715Z
(The Toko Electric Corporation)
See pin 1.
Continued on next page.
-
2T
-
9T
-
86T
Q
O
80
L = 270 H
-
58T
-
7T
-
94T
f
O
= 450 kHz
Q
O
= 110
Includes an internal
180-pF capacitor.
SFU450B included.
-
22T
f = 10.7 MHz
Q
O
= 40
Includes an internal
82-pF capacitor.
Pin No.
Pin Function
Pin voltage (V)
Pin description
Equivalent circuit
No. 5688-5/9
LA1837
AM narrow band CF
connection
1.3 V
Recommended narrow band CF: BFU450
C4N (Murata Mfg. Co., Ltd.)
If the narrow band SD is not used, bypass
this circuit with a 50-
resistor and a 0.047-
F capacitor connected in series.
10
FM S-meter output
0 V
R
L
= 8 k
11
AM S-meter output
AM SD sensitivity
adjustment
0 V (AM)
The AM SD sensitivity is adjusted with the
value of the external resistor connected
between this pin and ground.
12
AM and FM IF buffer
output, output control
switch (mute switch)
0 V
V13
0.5 V: Reception state
1.4 V
V13
2.2 V: IF buffer output turned
on
V13
3.5 V: IF buffer output and muting are
turned on
13
Phase comparator
low-pass filter
(FM/AM switching)
V
CC
1.4 (FM)
0 V (AM)
Connecting this pin to ground through a
resistor sets the IC to AM mode.
Resistor value limits:
2.7 k
(when V
CC
= 7 V)
3.9 k
(8 V) 5.1 k
(9 V)
6.2 k
(10 V) 7.5 k
(11 V)
14
Pilot detector low-pass
filter (forced mono)
(VCO stop)
V
CC
1.0
If a current of 50 A or greater flows from
this pin, the system is forced to mono.
Connecting this pin to ground stops the
VCO.
The resistor limit values are the same as for
pin 14.
15
Post amplifier input and
output
Vreg
Vreg
Output impedance r
o
= 200
Pin 16: right output, pin 17: left output
Inverting inputs
Pin 18: right input, pin 19: left input
R
NF
= 33 k
16
17
18
19
MPX output
3.5 V
3.5 V
Output impedance r
o
= 3.3 k
Pin 20: right de-emphasis
Pin 21: left de-emphasis
20
21
Continued on next page.
Continued from preceding page.
No. 5688-6/9
LA1837
Continued from preceding page.
Pin No.
Pin Function
Pin voltage (V)
Pin description
Equivalent circuit
MPX input
2.9 V
Input impedance r
i
= 20 k
22
FM demodulator output
2.8 V (FM)
2.8 V (AM)
Output impedance r
o
= 3.0 k
The separation can be modified by inserting
a capacitor between this pin and ground.
Set V
O
sub/V
O
main to be about 0 dB.
23
AM detector output
0 V (FM)
0.5 V (AM)
Output impedance r
o
= 3.3 k
The AM frequency characteristics can be
modified by adjusting the time constants of
the circuits between this pin and pin 22, and
between this pin and ground.
24
AM AGC
0 V (FM)
0.5 V (AM)
The built-in load resistor R = 11 k
.
25
AFC
Vreg
The FM SD bandwidth can be modified with
the external resistor connected between
this pin and pin 28.
26
AM RF input
Vreg
Use this pin at the same potential as pin 28.
27
REG
Vreg
Vreg = 3.6 V
28
OSC
Vreg
Use an oscillator coil between this pin and
pin 28.
29
Oscillator buffer output,
FM SD sensitivity
adjustment
1.6 V (FM)
1.3 V (AM)
The FM SD sensitivity can be modified with
the external resistor connected between
this pin and ground.
Output impedance r
o
= 20
30
No. 5688-7/9
LA1837
Output dBm
Input dB
Overall FM Characteristics
Total harmonic distortion, THD %
S-meter output, V
SM
V
Iinput dB
FM THD/VSM Characteristics
Total harmonic distortion, THD %
Frequency, f
C
MHz
FM THD Band Characteristics
Total harmonic distortion, THD %
Frequency, freq kHz
Distortion vs. Frequency Characteristics
Separation dB
Frequency, freq kHz
Separation vs. Frequency Characteristics
Vobat dB
Frequency, f
S
Hz
Adjacent Channel Interference Rejection Ratio
Capture range %
Pilot mV
Capture Range Characteristics
SD on dB
Rsdadj k
SD Sensitivity Adjustment Characteristics
Referenced to the L-R
demodulated output.
FM THD/V
SM
Characteristics
No. 5688-8/9
LA1837
SD BW kHz
Radj k
SD Sensitivity Adjustment Characteristics
Total harmonic distortion, THD %
S-meter output, V
SM
V
Input dB
AM THD/V
SM
Characteristics
Output dBm
Input dB
Overall AM Characteristics
Output voltage, V
O
dBV
Frequency, fm kHz
AM Detector Output Frequency Characteristics (1)
Output voltage, V
O
dBV
Frequency, fm kHz
AM Detector Output Frequency Characteristics (2)
Separation, Sep dB
S/N dB
Ambient temperature, Ta C
Separation vs. Ambient Temperature Characteristics
Total harmonic distortion, THD %
Ambient temperature, Ta C
Distortion vs. Ambient Temperature Characteristics
Output
No. 5688-9/9
LA1837
This catalog provides information as of August, 1997. Specifications and information herein are subject to
change without notice.
s
No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace
equipment, nuclear power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of
which may directly or indirectly cause injury, death or property loss.
s
Anyone purchasing any products described or contained herein for an above-mentioned use shall:
Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and
distributors and all their officers and employees, jointly and severally, against any and all claims and litigation and all
damages, cost and expenses associated with such use:
Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on
SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors or any of their officers and employees
jointly or severally.
s
Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for
volume production. SANYO believes information herein is accurate and reliable, but no guarantees are made or implied
regarding its use or any infringements of intellectual property rights or other rights of third parties.
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