TL H 7888
LM1800
Phase-Locked
Loop
FM
Stereo
Demodulator
April 1987
LM1800 Phase-Locked Loop FM Stereo Demodulator
General Description
The LM1800 is a second generation integrated FM stereo
demodulator using phase locked loop techniques to regen-
erate the 38 kHz subcarrier The numerous features inte-
grated on the die make possible a system delivering high
fidelity sound while still meeting the cost requirements of
inexpensive stereo receivers More information available in
AN-81
Features
Y
Automatic stereo monaural switching
Y
45 dB power supply rejection
Y
No coils all tuning performed with single potentiometer
Y
Wide operating supply voltage range
Y
Excellent channel separation
Y
Emitter follower output buffers
Connection Diagram
Order Number LM1800N
See NS Package Number N16A
TL H 7888 1
Top View
Typical Application
TL H 7888 2
C1995 National Semiconductor Corporation
RRD-B30M115 Printed in U S A
Absolute Maximum Ratings
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage
18V
Power Dissipation (Note 3)
1500 mW
Operating Temperature Range
0 C to
a
70 C
Operating Supply Voltage Range
a
10V to
a
18V
Storage Temperature Range
b
65 C to
a
150 C
Lead Temperature (Soldering 10 sec)
260 C
Electrical Characteristics
(Note 1)
Parameter
Conditions
Min
Typ
Max
Units
Supply Current
Lamp ``Off''
21
30
mA
Lamp Driver Saturation
100 mA Lamp Current
1 3
1 8
V
Lamp Driver Leakage
1 0
nA
Pilot Level for Lamp ``ON''
Pin 11 Adjusted to 19 00 kHz
15
20
mVrms
Pilot Level for Lamp ``OFF''
Pin 11 Adjusted to 19 00 kHz
3 0
7 0
mVrms
Stereo Lamp Hysteresis
3 0
6 0
dB
Stereo Channel Separation
100 Hz (Note 2)
40
dB
1000 Hz (Note 2)
30
45
dB
10000 Hz (Note 2)
45
dB
Monaural Channel Unbalance
200 mVrms 1000 Hz Input
0 3
1 5
dB
Monaural Voltage Gain
200 mVrms 400 Hz Input
140
200
260
mVrms
Total Harmonic Distortion
500 mVrms 1000 Hz Input
0 4
1 0
%
Total Harmonic Distortion
500 mVrms 1000 Hz Input 1800A Only
0 1
0 3
%
Capture Range
25 mVrms of Pilot
g
2 0
g
6 0
% of f
o
Supply Ripple Rejection
200 mVrms of 200 Hz Ripple
35
45
dB
Dynamic Input Resistance
20
45
kX
Dynamic Output Resistance
900
1300
2000
X
SCA Rejection
(Note 4)
70
dB
Ultrasonic Freq Rejection
Combined 19 and 38 kHz Ref to Output
33
dB
Note 1
T
A
e
25 C and V
a
e
12V unless otherwise stated
Note 2
The stereo input signal is made by summing 123 mVrms LEFT or RIGHT modulated signal with 25 mVrms of 19 kHz pilot tone measuring all voltages with
an average responding meter calibrated in rms The resulting waveform is about 800 mVp-p
Note 3
For operation in ambient temperatures above 25 C the device must be derated based on a 150 C maximum junction temperature and a thermal resistance
of 80 C W junction to ambient
Note 4
Measured with a stereo composite signal consistency of 80% stereo 10% pilot and 10% SCA as defined in the FCC Rules on Broadcasting
Note 5
VCO ``OFF'' curve represents the distortion attainable using good 19 kHz and 38 kHz filters
2
Typical Performance Characteristics
Supply Ripple Rejection
TL H 7888 3
Channel Separation
TL H 7888 4
Monaural Distortion
vs Input Amplitude
TL H 7888 5
Monaural Distortion
vs Frequency
TL H 7888 6
3
LM1800
Phase-Locked
Loop
FM
Stereo
Demodulator
Physical Dimensions
inches (millimeters)
Molded Dual-In-Line Package (N)
Order Number LM1800N
NS Package Number N16A
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DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION As used herein
1 Life support devices or systems are devices or
2 A critical component is any component of a life
systems which (a) are intended for surgical implant
support device or system whose failure to perform can
into the body or (b) support or sustain life and whose
be reasonably expected to cause the failure of the life
failure to perform when properly used in accordance
support device or system or to affect its safety or
with instructions for use provided in the labeling can
effectiveness
be reasonably expected to result in a significant injury
to the user
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