92706 / O3105 MS OT B8-3807 No.8271-1/9
Semiconductor Components Industries, LLC, 2013
May , 2013
http://onsemi.com
LA1837M
Overview
The LA1837M is a single-chip AM/FM tuner IC that provides AM and FM IF and multiplex decoding circuits for
electronic tuni ng and was develope d for use in hom e stereo systems. It pro vides both SD and IF co unting techniques for
optimal implementation of au tomatic station selection.
Features
• On-chip MPX VCO circuit (no external components required).
• Adjacent channel interference rejection function (third order and fifth order).
• Supports both the SD an d IF counting technique (built-in SD speedu p function).
• The AM and FM SD sensitivity can be set independently.
• The AM and FM output levels can be set independently.
• Improved basic FM reception performance.
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, SD, S curve detection, IF buffer output
• Multiplex stereo decoding: PLL stereo decoder, stereo indicator, forced monaural, VCO stop function, post amplifier,
audio muting, adjacent channel interference rejection function
Specifications
Maximum Ratings at Ta = 25°C
Parameter Symbol Conditions Ratings Unit
Maximum supply voltage VCC max 12 V
Allowable power dissipation Pd max Ta≤70°C* 550 mW
Operating temperature Topr -20 to +70 °C
Storage temperature Tstg -40 to +125 °C
*: Mounting board: 114.3×76.1×1.6mm glass epoxy board
Ordering number : EN8271
Ordering number : EN8271
Monolithic Linear IC
Single-Chip AM/FM Tuner IC
for Home Stereo Systems
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating
Cond itions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability.
LA1837M
No.8271-2/9
Operating Conditions at Ta = 25°C
Parameter Symbol Conditions Ratings Unit
Recommended supply voltage VCC 9 V
Operating supply voltage range VCC op 7.0 to 11.0 V
Electrical Characteristics at Ta = 25°C VCC = 9.0V, in the specified circuit.
Parameter Symbol Conditions Ratings Unit
min typ max
[FM Mono Characteristics] fc = 10.7MHz, fm = 1kHz, with the coil adjusted so that VAFC - VREG = 0V.
Current drain ICCO-FM No input 18 31 44 mA
Demodulator output VOFM 100dBµ, 100% mod, pin 16 output 730 1100 1460 mVrms
Channel balance C.B-mono 100dBµ, 100% mod, pin 16 output / pin 17 output -1.5 0 +1.5 dB
Total harmonic
distortion (mono) THDFM1 100dBµ, 100% mod, pin 16 output 0.3 1.3 %
THDFM2 100dBµ, 200% mod, pin 16 output 1.0 5.0 %
Signal-to-noise ratio S/NFM 100dBµ, 100% mod, pin 16 output 72 80 dB
AM rejection ratio AMR 100dBµ, AM 30% mod, pin 16 output 45 65 dB
Input limiting voltage -3dBL.S Referenced to 100dBµ, 100% mod, the input for output
is -3dB down. 26 32 38 dBμ
LED on sensitivity SDON-FM 51 60 69 dBμ
LED on bandwidth SDBW 100dBµ 85 120 170 kHz
IF counter buffer output VIFBUFF-FM 100dBµ, pin 13 output 80 120 160 mVrms
S-meter output VSM FM1 0dBµ, pin 11 output 0 0.1 0.5 V
VSM FM2 100dBµ, pin 11 output 3.6 4.3 5.0 V
Muting attenuation Mute Alt 100dBµ, 100% mod, the pin 16 output 75 85 dB
[FM Stereo Characteristics] fc = 10.7MHz, 100dBμ, fm = 1kHz, L+R = 90%, pilot = 10%
Separation: L SepL Lmod. pin 16 output / pin 17 output 30 45 dB
Separation: R SepR Rmod. pin 17 output / pin 16 output 30 45 dB
Stereo on level STON The pilot mod such that V7 < 0.7V 1.3 2.7 5.0 %
Stereo off level STOFF The pilot mod such that V7 > 4.5V 1.5 %
Total harmonic
distortion (main) THD main L+R mod. Pin 16 output 0.3 1.3 %
Adjacent channel
interference rejection
ratio
Brej-3rd fs = 113kHz, Vs = 90%, Pilot = 10%
Pin 16 output, versus L-R mod. 1kHz demodulator output 40 dB
Brej-5th fs = 189kHz, Vs = 90%, Pilot = 10%
Pin 16 output, versus L-R mod. 1kHz demodulator output 40 dB
[AM Characteristics]
Current drain ICCO-AM No input 15 25 35 mA
Output detector VOAM1 23dBµ, 30% mod, pin 16 output 100 180 360 mVrms
VOAM2 80dBµ, 30% mod, pin 16 output 200 320 500 mVrms
Signal-to-noise ratio S/N AM1 23dBµ, 30% mod, pin 16 output 18 22 dB
S/N AM 2 80dBµ, 30% mod, pin 16 output 49 55 dB
Total harmonic
distortion THD AM 1 80dBµ, 30% mod, pin 16 output 0.4 1.2 %
THD AM 2 80dBµ, 80% mod, pin 16 output 1.0 4.0 %
LED-ON sensitivity SDOn-AM 17 27 37 dBμ
Oscillator buffer output VOSC-AM No input, pin 30 output 110 160 220 mVrms
IF counter buffer output VIFBuff-AM 80dBµ, non-mod, pin 13 output 160 220 300 mVrms
ST IF output VSTIF-AM 80dBµ, non-mod, pin 7 output 16 34 48 mVrms
S-meter output VSM-AM 0dBµ, non-mod 0 0 0.2 V
LA1837M
No.8271-3/9
Package Dimensions
unit : mm
3073C
Block Diagram
LA1837M
No.8271-4/9
Coil Specifications
Pin Function
Pin No. Pin Pin
voltage Equivalent circuit Pin function
1 FM IF input Vreg Input impedance ri = 330 Ω
2 AM mixer output VCC Connect the mixer coil between this pin and VCC.
3 FM IF input
bypass Vreg See pin 1 Also used for the multiplex regulator filter
4 AM IF input Vreg Input impedance ri = 2 kΩ
5 GND 0V
6
7
TU-LED,
ST-LED,
AM - IF output
VCC
VCC Active low
Open collector
AM stereo IF output (pin 7)
This pin must be set up with an influx current under 150µA.
8 VCC
9 FM detector VCC Recommended detector coil
600BEAS-9715Z (The Toko Electric Corporation)
Continued on nex t pa ge.
• AM oscillator (for the DUT)
HW-50425
(
Mitsumi Electric Co.
,
Ltd.
)
• FM-DET
600BEAS-9715 Z (To ko Electric Corporation)
• IFT
YD-1073-1
(
Mitsumi Electric Co.
,
Ltd.
)
LA1837M
No.8271-5/9
Continued from preceding page.
Pin No. Pin Pin
voltage Equivalent circuit Pin function
10 AM narrow band
ceramic filter
connection
1.3V Recommended narrow band ceramic filter
BFU450C4N (Murata Mfg. Co., Ltd.)
When the narrow band SD fun ction is not used, bypass this circuit
by connecting a 50Ω resistor and a 0.047µF capacitor in series.
11 FM S-meter
output 0V RL = 8kΩ
12 AM S-meter
output,
AM SD
sensitivity
adjustment
0V (AM) The AM SD sensitivity can be adjusted with an external resistor
between this pin and ground.
13 AM/FM IF buffer
output,
Output control
switch (muting
switch)
0V V13 ≤ 0.5V: Reception state
1.4V ≤ V13 ≤ 2.2V: IF buffer output on
V13 ≥ 3.5V: IF buffer output and muting on
14 Phase
comparator
low-pass filter
(FM/AM
switching)
VCC-1.4
(FM)
0V (AM)
The IC switches to AM mode w hen this pin is connected to ground
through a resistor.
Resistor value limits: 2.7kΩ (when VCC = 7V)
3.9kΩ (8V) 5.1kΩ (9V)
6.2kΩ (10V) 7.5kΩ (11V)
15 Pilot detector
low-pass filter
(Forced
monaural)
(VCO stop)
VCC-1.0 When a current of over 50µA is sourced by this pin, the IC
switches to forced monaural mode.
The VCO is stopped if this pin is connected to ground.
The resistor value limits are the same as for pin 14.
16
17
18
19
Post amplifier
I/O Verg
Verg Output impedance ro = 200Ω
Pin 16: right output, pin 17: left output
Inverting input pins
Pin 18: right input, pin 19: left input
RNF = 33kΩ
20
21 Multiplex output 3.5V
3.5V Output impedance ro = 3.3kΩ
Pin 20: Right channel deemphasis
Pin 21: Left channel deemphasis
22 Multiplex input 2.9V Input impedance ri = 20kΩ
23 FM
demodulated
output
2.8V (FM)
2.8V (AM) Output impedance ro = 3.0kΩ
The separation can be adjusted with an external capacitor
connected between this pin and ground.
The VOsub/VOmain ratio is set to be approximately 0dB.
Continued on nex t pa ge.
LA1837M
No.8271-6/9
Continued from preceding page.
Pin No. Pin Pin
voltage Equivalent circuit Pin function
24 AM detector
output 0V (FM)
0.5V (AM) Output impedance ro = 3.3kΩ The AM frequency characteristics
can be adjusted w ith an RC circuit connected between pin 22 and
ground.
25 AM AGC 0V (FM)
0.5V (AM) Internal load resistance R = 11kΩ
26 AFC Vreg The FM SD bandwidth can be adjusted with an external resistor
connected between this pin and pin 28.
27 AM RF input Vreg This pin must be held at the same potential as pin 28
28 REG Vreg Vreg = 3.6V
29 OSC Vreg Connect the oscillator coil between this pin and pin 28.
30 Oscillator buffer
output, FM SD
sensitivity
adjustment
1.6V (FM)
1.3V (AM) The FM SD sensitivity can be adjusted with an external resistor
connected between this pin and ground.
Output impedance ro = 20Ω
LA1837M
No.8271-7/9
LA1837M
No.8271-8/9
LA1837M
PS No.8271-9/9
Test Circuit
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