ICs for FM/AM Tuner
s
Overview
The AN7280S is an FM front-end IC designed for DTS
except RF amp. of car radio. It features built-in local oscil-
lation frequency buffer output, PIN diode driver for anten-
na damping and SSC (search stop control).
s
Features
High sensitivity, high S/N ratio
Good IM characteristics at strong input
Available for two loop AGC (keyed AGC)
Pre IF amp. gain variable
PIN diode driver (ADX) built-in
AN7280S
FM Front-end IC for Car Radio
Unit : mm
0.1
0.1
1.5
0.2
0.3
0.65
0.15
0.4
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
0.4
0.25
1.27
12.6
0.3
5.4
0.3
7.7
0.3
20
19
18
17
16
15
14
13
12
11
1
2
3
4
5
6
7
8
9
10
ADX
Mixer
Buffer
Buffer
OSC
Det.
AGC Amp.
IF Amp.
V
REG
SSC
GND
GND
V
CC
s
Block Diagram
20-Lead SOP Package (SOP020-P-0300B)
AN7280S
ICs for FM/AM Tuner
V
CC
I
CC
P
D
T
opr
T
stg
Supply Voltage
Supply Current
Power Dissipation
Operating Ambient Temperature
Storage Temperature
V
mA
mW
C
C
Parameter
Symbol
Rating
Unit
s
Absolute Maximum Ratings
(Ta=25C)
9.2
50
460
40 ~ + 85
55 ~ + 150
s
Recommended Operating Range
(Ta=25C)
Parameter
Symbol
Range
Operating Supply Voltage Range
V
CC
6.8V ~ 9.2V
Parameter
Symbol
Condition
min.
typ.
max.
Unit
s
Electrical Characteristics
(Ta=25C)
S/N Ratio
Local Oscillation Level
IF Output Level
AGC Level (L)
AGC Level (H)
N
OUT
V
OSC
V
OUT
V
AGC (L)
V
AGC (H)
V
CC
= 8V, V
in
=17dB
No modulation
However, S= output at 400Hz, 30%modulation
V
CC
= 8V, f
OSC
= 108.7MHz
Measured by Pin4, No signal input
V
CC
= 8V, V
in
= 51dB
V
CC
= 8V, V
in
= 67dB
V
CC
= 8V, V
in
= 53dB
22
219
41
6
30
384
58
0.05
6.5
435
82
0.5
dB
mV
mV
V
V
s
Characteristics Curve
Level Diagram
50
40
30
20
10
0
L
e
v
e
l
(
d
B
)
V
CC
=8V
f
in
=98MHz
Mod.=22.5kHz
f
m
=1kHz
IF : AN7256
400Hz HPF ON
Input/Output Characteristics
Frequency Change
0
20
40
60
80
V
in
(dB
V)
A
F
O
U
T
(
d
B
)
40
0
20
80
60
24.5
13.5
8.5
43.5 (max.)
20
15
10
5
0
5
10
15
f
in
(MHz)
V
i
n
(
d
B
V
)
98
96
90
88
94
92
106 108
104
102
100
V
CC
=8V
f
in
=1kHz
Mod.=22.5kHz
IF : AN7256
Mix.
IF
OUT
0.01
F
MS3
080
IN
IFT
330
IFAmp.
16.0 (min.)
Practical Sensitivity (S/N=30dB)
Limiting Sensitivity
Residual Noise
ICs for FM/AM Tuner
AN7280S
No Input
IF-Amp. Gain Adjustment
40
30
20
10
0
Pin13 Adjusting Resistance (
)
G
a
i
n
(
d
B
)
0
1k
10K
V
CC
= 8V
f
in
= 18MHz
Radj. is Piny external resistance
(AGC Start Point Variable)
AGC ON Level
110
100
90
80
70
60
50
0
Pin7 V
cont in
(V)
V
i
n
(
d
B
V
)
2.2
0
1.4
1
1.8
4
Radj.=
No Input
Supply Voltage Dependence
35
30
25
20
15
10
5
0
5
4
3
2
1
0
V
CC
(V)
I
t
o
t
(
m
A
)
V
r
e
f
(
V
)
6
0
2
4
12
10
8
Supply Voltage Change
110
100
60
50
20
10
0
V
CC
(V)
V
i
n
(
d
B
V
)
8
6
7
10
9
V
CC
= 8V
f
in
= 98MHz No Adjustment
Pin7
= HIGH
Pin9 =
High
Pin9 = Low
Local Oscillation Level
AGC ON Level
Practical Sensitivity
Limiting Sensitivity
Total Gain
Temperature Characteristics
10
8
6
4
2
0
2
4
6
8
10
Ta (C)
T
o
t
a
l
G
a
i
n
(
d
B
)
20
40
0
40
20
100
60
80
0dB= 43.5dB
V
ref
I
tot
Supply Voltage Dependence
11
10
9
8
7
6
5
4
5
4
3
2
1
0
V
CC
(V)
A
G
C
O
U
T
V
t
(
V
)
S
S
C
O
N
L
e
v
e
l
(
V
)
8
5
6
7
11
12
10
9
SSC ON Level
V
t
IC for IF/DET
is normal temperature
Mixer+IFAmp.
V
CC
= 8V
Temperature Characteristics
80
70
60
50
40
30
20
10
0
Ta (C)
V
i
n
(
d
B
V
)
0
60 40 20
60
80 100
40
20
Practical Sensitivity (S/N=30dB)
Limiting Sensitivity
AGC ON Level (max. Gain)
AGC Start Point
Temperature Characteristics
105
100
95
90
85
80
75
70
65
60
55
Ta (C)
V
i
n
(
d
B
V
)
20
40
0
40
20
100
60
80
Pin7=1V
Pin6=GND
Pin9=OPEN
Pin7=HIGH
Pin6=GND
Pin9=OPEN
Pin7=HIGH
Pin6=OPEN
Pin9=5V
Pin7=HIGH
Pin6=OPEN
Pin9=OPEN
f=10.7MHz
13
IF Amp.
Input
Output
330
27dB
Radj.= 0
Amp. Gain Adjustment
with AGC
110
100
90
80
70
60
50
Pin6 Adjusting Resistance (
)
A
G
C
O
N
L
e
v
e
l
(
d
B
V
)
0
1k
10K
AN7280S
ICs for FM/AM Tuner
IF Amp. Output Saturation Level
Temperature Characteristics
5
4
3
2
1
0
1
2
3
4
5
Ta (C)
I
F
A
m
p
.
O
u
t
p
u
t
S
a
t
u
r
a
t
i
o
n
L
e
v
e
l
(
d
B
)
20
40
0
40
20
100
60
80
V
CC
=8V
SSC ON Level
Temperature Characteristics
5
4
3
2
1
0
Ta (C)
P
i
n
o
V
o
l
t
a
g
e
(
V
)
20
40
0
40
20
100
60
80
SSC Input Pin
9
20
1
19
2
18
3
17
4
16
5
15
6
14
7
13
8
12
9
11
10
GND
PIN
D
AGC
RF
IN
Pass
Con.
Mix
OUT
Mix
OUT
IF
IN
IF
Gain
Adj
Pass
Con.
IF
OUT
E
B
Pass
C
OSC
OUT AGC
2 Loop
IN
GND SSC
V
CC
AGC
Gain
Adj
AN7280S
+
KVC1340
120k
3
p
F
1
2
p
F
56pF
5
6
p
F 0.
0
1
F
0
.
0
0
1
F
1
F
0
.
0
1
F
180k
0
.
0
1
F
To IF
0
.
0
1
F
0
.
0
1
F
4
p
F
4
7
0
330
CF
0
.
0
1
F
1k
0
.
0
0
1
F
1
5
p
F
0
.
0
1
F
1
2
p
F
8
2
0
22
3
3
0
1
0
0
k
1
0
0
k
8
2
k
18pF
3SK1311
KVC1340
1
0
0
k
18pF
0.001
F
MA551
ANT
KVC1340
1
0
0
k
V
T
0V
0V
5V 5V
Control
Voltage
At Search
At Normal
Produced by MATSUSHITA
IFT : ZIF5EF021B
V
CC
s
Application Circuit
ICs for FM/AM Tuner
AN7280S
s
Pin Descriptions
Equivalent Circuit
Pin Name
Pin No.
Description
1
OSC Emitter
Local oscillation transistor emitter pin
2
OSC Base
Local oscillation transistor base pin
3
OSC By-pass
4
OSC Buffer Output
Pin for output OSC signal to pre-scaler
5
Level Detection Output
6
AGC Amp. Gain Adjustment
7
Control Signal Input
8
GND
9
SSC Input
10
V
CC
AGC signal output pin for RF-Amp.
secondary gate
Pin for adjusting AGC Amp. gain by
external resistance
Pin for adjusting AGC-Amp. gain through
input of control signal from IF section
Pin for adjusting AGC-Amp. gain through
input of control signal from microcomputer
V
ref
by-pass pin for mixer,OSC buffer,OSC
section
2
1
V
ref
4
V
ref
750
5
V
CC
.70
A
6
5.6k
7
1.5k
1.5V
V
ref
9
70k
39k
+
3
5V
AN7280S
ICs for FM/AM Tuner
s
Pin Descriptions (Cont.)
Equivalent Circuit
Pin Name
Pin No.
Description
12
IF-Amp. By-pass
IF-Amp. by-pass pin
14
IF-Amp. Input
IF-Amp. input pin
15
16
11
IF-Amp.
IF-Amp. output pin
Mix. Output
19
ADX Output
20
GND
Oscillator GND
PIN diode driver output pin
Determine maximum current to PIN diode
by Pin19 external resistance value.
17
Mix. By-pass
Mixer by-pass pin
18
Mix. Input
Mixer input pin
13
IF-Amp. Gain Adjustment
Pin for adjusting IF-Amp. gain by external
resistance
Mixer output pin
V
CC
11
240
3k
Z
OUT
.300
12
14
330
13
12k
340
15
16
17
18
2.2k
2.2k
19
ICs for FM/AM Tuner
AN7280S
s
Operational Description
Loop AGC
The AN7280S uses 2Loop AGC for AGC circuit. 2Loop AGC controls AGC output by using mixer output (IFT first side)
signal and FMIF control voltage (level meter output), which is a very favorable system for disturbance characteristics,
etc.
RFAmp.
Mixer
IFT
IFAmp.
Control Voltage Output
To N.C.
AGC start point (Mixer input level at V
AGC
< 3V) changes in proportion to Pin6 external resistance (following R
1
) , Pin
7 applied voltage (Determine IF control voltage by R
2
, R
3
resistance division) SSC ON/OFF
Variable width at R
1
28dB (however, V
7
3V, V
9
= 0V)
Variable width at R
7
40dB (however, R
1
=
, V
9
= 0V)
Variable width at R
9
10dB (however, R
1
=
, V
7
3V)
3
V
AGC
about 4.7V
5
6
7
9
R
1
R
2
R
3
V
REF
AGC Output
AGCAdj
Vcont IN
SSC IN
from microcomputer
FMIF
Control voltage
SSC
Change AGC start point by microcomputer control signal at seek/reception time.
Use at SSC ON V
9
> 3.5V
Use at SSC OFFV
9
< 1.5V
* SSC is designed as precondition for switching operation at microcomputer control signal.
FMIF
AGC
Amp.
AGC
Det.
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