91004 JO IM No.7931-1/10
LA1845NV
The LA1845NV is designed for use in mini systems and is a single-chip tuner IC that provides electronic tuning
functions using SD/IF-count technique. It incorporates a pilot canceler and an adjustment-free MUX VCO circuit,
thus allows additional parts to be reduced.
Functions
AM : RF amplifier, mixer, oscillator, IF amplifier, detector, AGC, SD, oscillator buffer, IF buffer, stereo IF output,
AGC time constant switch
FM IF : IF amplifier, quadrature detector, S-meter, SD (signal detection), S-curve detection, IF buffer output
MPX : PLL stereo decoder, stereo display, forced monaural, VCO stop, audio muting, adjacent channel interference
rejection function, pilot canceler
Features
Integrated MPX VCO (ceramic resonators are no longer required.)
Built-in adjacent channel interference rejection function (114kHz, 190kHz)
Supports both SD and IF-count techniques
Both FM SD sensitivity and bandwidth can be set
Pilot canceler built in.
Maximum Ratings
at Ta = 25
C
Parameter Symbol
Conditions
Ratings Unit
Maximum Power Supply Voltage
VCC max
6
V
Allowable Power Consumption
Pd max
Ta = 80C with board
114.3mm
76.1mm
1.6mm material :
Glass epoxy resin
360
mW
Operating Temperature
Topr
-20 to +80
C
Storage Temperature
Tstg
-40 to +125
C
Operating Conditions
at Ta = 25
C
Parameter Symbol
Conditions
Ratings Unit
Recommended Supply Voltage
VCC
5
V
Operating Supply Voltage Range
VCC op
Ta = 80C
4.3 to 5.5
V
Ordering number : ENN*7931
Monolithic Linear IC
Single-Chip Home Stereo IC
LA1845NV
No.7931-2/10
Electrical Characteristics
Operating Characteristics
at VCC = 8V, in the specified test circuit.
FM Mono Characteristics
at fc = 10.7MHz, Vi = 100dB
, fm = 1kHz, Modulation = 75kHz
Ratings
Parameter Conditions
min typ max
Unit
Current Drain
With no input signal
20
30
40
mA
Demodulator Output
100dB
, 100% modulation, fm = 1kHz
230
360
460
mVrms
Total Harmonic Distortion
100dB
, 100% modulation, fm = 1kHz
0.35
1.5
%
Signal-to-Noise Ratio
100dB
, 100% modulation, fm = 1kHz
73
80
dB
AM Rejection Ratio
100dB
, AM = 30% modulation, fm = 1kHz
47
65
dB
3dB Sensitivity
100dB
, 100% modulation, fm = 1kHz Output reference,
-3dB input
32 40
dB
SD Sensitivity
0% modulation
38
47
56
dB
IF Counter Buffer Output
100dB
200
275
400
mVrms
Mute Attenuation
100dB
, 100% modulation, fm = 1kHz
76
dB
FM Stereo Characteristics
at fc = 10.7MHz, Vi = 100dB
, L+R = 90%, Pilot = 10%, fm = 1kHz
Ratings
Parameter Conditions
min typ max
Unit
Separation
L+R = 90%, Pilot = 10%, fm = 1kHz
30
42
dB
Stereo On Level
Pilot input
1.5
3.5
5.5
%
Total Harmonic Distortion
Pilot input
0.45
1.5
%
Adjacent Channel Rejection Ratio 1
fs = 113kHz, VS = 90%, Pilot = 10% ;
The left-right modulation, demodulated output
36 dB
Adjacent Channel Rejection Ratio 2
fs = 189kHz, VS = 90%, Pilot = 10% ;
The left-right modulation, demodulated output
41 dB
Carrier Leak
L+R = 90%, Pilot = 10% reference, Pilot = 10% output
38
44 dB
AM Characteristics
at fc = 1000kHz, Vi = 80dB
, fm = 1kHz, Modulation = 30%
Ratings
Parameter Conditions
min typ max
Unit
Current Drain
With no input signal
13
27
39
mA
Detector Output 1
23dB
, 30% modulation, fm = 1kHz
40
80
160
mVrms
Detector Output 2
80dB
, 30% modulation, fm = 1kHz
90
160
230
mVrms
Signal-to-Noise Ratio 1
23dB
, 30% modulation, fm = 1kHz
17
23
dB
Signal-to-Noise Ratio 2
80dB
, 30% modulation, fm = 1kHz
46
52
dB
Total Harmonic Distortion 1
80dB
, 30% modulation, fm = 1kHz
0.4
1.1
%
Total Harmonic Distortion 2
107dB
, 30% modulation, fm = 1kHz
0.5
1.3
%
SD Sensitivity
0% modulation
11
20
29
dB
Local Oscillator Buffer Output
With no input signal
100
140
200
mVrms
IF Counter Buffer Output
23dB
140
285
400
mVrms
LA1845NV
No.7931-3/10
Package Dimensions
unit : mm
3175B
Pin Description
Pin No.
Pin function
Pin voltage
Equivalent circuit
Notes
1
FM IF input
Vreg
Input impedance ri = 330
2
AM mixer output
VCC
Connect the mixer coil between this pin and VCC
3
REG
2.1
Vreg = 2.1V
4
AM IF input
Vreg
Input impedance ri = 2k
5 GND
0V
6
7
Tu-LED
ST-LED/AF-IF
output
VCC
Active
low
Open collector
8 FM
detector
VCC
The 600BEAS-10471 (Toko Mfg. Co., Ltd.) is
recommended for detector coil.
9 VCC
Continued on next page.
1
3
2
3
4
6
7
LA1845NV
No.7931-4/10
Continued from preceding page.
Pin No.
Pin function
Pin voltage
Equivalent circuit
Notes
10
AM/FM IF counter
output, output
control switch, mute
switch
0V
V100.5V : Reception state
1.4VV102.2V : Muting on
V103.5V : IF counter output and muting on
11 Phase
comparator
low-pass filter
(AM/FM switching)
VCC-1.0
The device operates in AM mode when a current of
over 200
A flows from pin. 12.
12
Pilot detector low-
pass filter (Forced
mono) (VCO stop)
VCC-1.0
The device is forced to monaural when a current of
over 50
A flows from this pin.
The VCO is stopped when a current of over 200
A
flows from this pin.
The limit values for the resistor are the same as
those for pin 11.
13
14
L outputs
R outputs
3.2V
Output impedance ro = 3.3k
15 Pilot
canceler
output
Vreg
16
Decoder input
Vreg
Inverting input pin
RNF = 20k
17
PLL input
Vreg
Input impedance ri = 20k
18 FM
demodulator
output
Vreg+0.7
Output impedance ro = 2.3k
The channel separation can be adjusted with an
external capacitor connected between this pin and
ground.
Continued on next page.
13
( )
14
16
RNF
15
3
17
18
10
11
12
LA1845NV
No.7931-5/10
Continued from preceding page.
Pin No.
Pin function
Pin voltage
Equivalent circuit
Notes
19
AM detector output
0V (FM)
1.5V (AM)
Output impedance ro = 3.3k
20 S
meter,
AM AGC
0.2V (FM)
0.9V (AM)
The resistance of the built-in resistor R is 13.9k
.
The SD response during seek operation is
determined with the external capacitor connected to
this pin.
21
AM RF input
Vreg
Must be used at the same potential as pin 22.
22
AFC
Vreg
The FM SD bandwidth can be adjusted with the
external resistor connected between this pin and
pin 3 (Vreg).
23 OSC
VCC
Connect the oscillator coil between this pin and pin
9 (VCC).
Note : Impedance of the secondary oscillator coil
must be 5k
or higher.
24 Oscillator
buffer
output,
FM SD sensitivity
adjustment
VCC-1.4
The FM SD sensitivity can be adjusted with an
external resistor connected to this pin.
Output impedance R = 200
Note : Resistance of the external resistor
connected to the pin 24 must be 3.3k
or higher.
23
R
24
20
R
19
21
22
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