Silan
Semiconductors
SC1088
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
1
FM RECEIVER CIRCUIT FOR BATTERY
SUPPLY
DESCRIPTION
The SC1088 is a bipolar integrated circuit for use in mono
portable and pocket radios. It is used when a minimum of perpheral
components (of small dimensions and low costs) is important. The
circuit contains a frequency-locked-loop(FLL) system with an
intermediate frequency(IF) of about 70kHz. Selectivity is achieved
by active RC-filters. De-tuning related to the IF and too weak input
signal is suppressed by the mute circuit.
FEATURES
* Equipped with all stages of a mono receiver from antenna to
audio output.
* Mute Circuit
* Search tuning with a single varicap diode
* Mechanical tuning with integrating AFC
* AM application supported
* Power supply polarity protection
* Power supply voltage down to 1.8V
SOP-16
APPLICATION
1. Mechanical tuning: This is possible with or without integrated AFC circuit
2. Electrical tuning: This is realized by one directional(band-up) search tuning facility, including RESET to the
lower-band limit.
PIN CONFIGURATIONS
SC1088
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
MUTE
VOAF
LOOP
VP
OSC
IF FB
CLP1
VOIF
VIIF
CLP2
VIRF
VIRF
CLIM
GND
CAP
TUNE
Silan
Semiconductors
SC1088
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
2
BLOCK DIAGRAM
Mix
e
r
VC
O
11
12
5
4
7
6
8
9
10
13
Al
l
pass
F
ilte
r
MU
TE
&
R
S
16
15
3
2
1
14
Sear
chi
n
g
t
uni
ng
Dem
odul
at
or
Loop
F
ilte
r
I
F
Li
m
t
er
+1
-1
V2
VP
V2
V2
V3
AF
V1
2.2k
2.2k
6k
5k
5.4k
6k
10k
82pF
68pF
220pF
70nH
78nH
680pF
V101
+3V
10nF
5.6k
68nF
RESET
0.1
F
1.8nF
22k
VoAF
180pF
330pF
3.3nF
3.9nF
0.1
F
470pF
RUN
22nF
SC1088
Not
e
:
V
1,
V
2
and
V
3
are
i
nt
ernal
v
o
lt
ages
.
AF
F
i
g.
1
B
loc
k
D
i
rgram
and
Applic
at
ion
C
irc
u
it
f
o
r
S
earc
h
T
uning.
Silan
Semiconductors
SC1088
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
3
ABSOLUTE MAXIMUM RATINGS
Characteristic
Symbol
Value
Unit
Supply Voltage
V
p
5
V
Operating Temperature
Tamb
-10 ~ +70
C
Storage Temperature
Tstg
-55 ~ +150
C
DC ELECTRICAL CHARACTERISTICS
(Tamb=25
C
,V
p
=3V ,Unless otherwise specified)
Parameter
Symbol
Test conditions
Min
Typ
Max
Unit
Supply Voltage(pin 4)
V
p
1.8
3.0
5.0
V
Supply Current(Pin 4)
I
p
4.2
5.2
6.6
mA
DC voltage of pin 1
V1
2.50
2.55
2.60
V
DC voltage of pin 3
V3
2.64
2.69
2.74
V
DC voltage of pin 6 and 7
V6,7
2.38
2.44
2.50
V
DC voltage of pin 8
V8
1.60
1.67
1.74
V
DC voltage of pin 9,10 and 13
V9,10,13
2.42
2.47
2.52
V
DC voltage of pin 11 and 12
V11,12
0.91
0.94
0.98
V
DC voltage of pin 15
V15
2.06
2.12
2.18
V
AF output current on pin 2
I2
45
60
80
A
Oscillator current on pin 5
I5
275
375
500
A
AC ELECTRICAL CHARACTERISTICS
Tamb=25
C,Vp=3V,Firf=96MHz modulated with
f=
22.5kHz and fm=1kHz deviation;EMF=0.3mV(e.m.f. at a
sourse impedance of 75
),and measurement taken in fig.3 Unless otherwise specified
Parameter
Symbol
Test conditions
Min
Typ
Max
Unit
V
oAF
=-3dB;V
oAF
=0dB at
Vi=1mV;see Fig. 2
Mute OFF
3
6
V
Mute ON
3
6
12
V
RF Sensitivityinput voltage
(S+N)/N=26dB
5
10
V
Signal handling
Vi(rms)
THD<10%,
f=
75kHz
200
mV
Signal-to -noise ratio
(S+N)/N
See fig.2
56
dB
f=
22.5kHz
1
1.4
%
Total Harmonic distortion
THD
f=
75kHz
2.4
3.3
%
AM suppression of output
voltage
AMS
FM: 1kHz;
75kHz
AM: 1kHz; MOD=80%
47
52
dB
Ripple rejection
RR
Vp=100mVrms,f=1kHz
7
10
dB
Audio output signal
Vo(rms)
R
L
=22k
60
85
120
mV
Search Tuning(with V101 and C16=0.1
F) See Fig.1
Minimum output voltage on pin
16
V16
Limiting point
Vp-
1.85
V
Tuning steepness
V/
t
Voltage at pin 16
95
210
420
mV/sec
Oscillator steepness
fosc/
t
1.25
2.83
5.6
MHz/sec
AFC steepness
I
AFC
/
V3
Voltage at pin 3
4.75
9.5
19
s
Silan
Semiconductors
SC1088
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
4
PIN DESCRIPTIONS
Pin No.
Symbol
Description
Pin No.
Symbol
Description
1
MUTE
Mute output
9
V
iIF
IF input to limiter amplifier
2
V
OAF
Audio frequency output
signal
10
C
LP2
Low-pass capacitor of IF
limiter amplifier
3
LOOP
AF loop filter
11
V
IRF
Radio frequency input
4
Vp
Supply voltage
12
V
IRF
Radio frequency input
5
OSC
Oscillator resonat circuit
13
C
LIM
Limiter offset voltage
capacitor
6
IF FB
IF feedback
14
GND
Ground
7
C
LP1
Low-pass capacitor of 1dB
amplifier
15
C
AP
All-pass filter capacitor.input
for search tuning
8
V
OIF
IF output to external coupling
capacitor(high-pass)
16
TUNE
Electrical tuning/AFC output
10
-6
10
-5
10
-4
10
-3
10
-2
-80
-60
-40
-20
0
20
S+N
Noise
2
2
1
1
V
OAF
(dB)
EMF (V)
1: Mute ON
2: Mute OFF
Fig. 2 Input sensitivity
Silan
Semiconductors
SC1088
HANGZHOU SILAN MICROELECTRONICS JOINT-STOCK CO.,LTD
5
TEST AND APPLICATION CIRCUIT
SC1088
15
16
13
14
11
12
9
10
2
1
4
3
6
5
8
7
+3V
MUTE
Disable
0.1
F
1.8nF
22k
22nF
1.2k
18pF
70nH
3.3nF
180pF
27pF
10nF
C1
3,9nF
330pF
0.1
F
470pF
220pF
68pF
10k
Rs=75
EMF
ViRF
V
OAF
82pF
78nH
MUTE
TUNE
V
OAF
C
AP
GND
LOOP
IF FB
OSC
C
LIM
V
IRF
V
IRF
C
LP1
C
LP2
V
IIF
V
OIF
V
P
Fig. 3 Test circuit and application for mechanical tuning
SC1088
15
16
13
14
11
12
9
10
2
1
4
3
6
5
8
7
+3V
68nF
1.
8nF
22k
22nF
1.2k
18pF
70nH
3.3nF
180pF
27pF
10nF
C1
3.
9nF
330pF
0.
1
F
470pF
220pF
68pF
10k
V
iRF
V
OAF
82pF
C2
V101
D1
0.
1
F
78nH
MUTE
TUNE
V
OAF
C
AP
GND
LOOP
IF FB
OSC
C
LIM
V
IRF
V
IRF
C
LP1
C
LP2
V
IIF
V
OIF
V
P
Fig. 4 Application circuit with AFC for mechanical tuning
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