![](/html/65/651e/651e10fcffef71245e0f3d0a97a48473d585919e652a1002b03eecf539154e58/bg1.png)
ICs for FM/AM Tuner
■ Overview
The AN7280S is an FM front-end IC designed for DTS
except RF amp. of car radio. It features built-in local oscillation frequency buffer output, PIN diode driver for antenna damping and SSC (search stop control).
■ 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
■ Block Diagram
20-Lead SOP Package (SOP020-P-0300B)
GND
20 19 18 17 16 15 14 13 12 11
V
REG
SSC
GND
IF Amp.
V
CC
ADX
OSC
1 2 3 4 5 6 7 8 9 10
Mixer
Buffer
Buffer
AGC Amp.
Det.
![](/html/65/651e/651e10fcffef71245e0f3d0a97a48473d585919e652a1002b03eecf539154e58/bg2.png)
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
■ Absolute Maximum Ratings (Ta=25˚C)
9.2
50
460
–40 ~ + 85
–55 ~ + 150
■ Recommended Operating Range (Ta=25˚C)
Parameter Symbol Range
Operating Supply Voltage Range
V
CC
6.8V ~ 9.2V
Parameter Symbol
Condition
min. typ. max. Unit
■ Electrical Characteristics (Ta=25˚C)
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)
VCC= 8V, Vin=17dBµNo modulation
However, S= output at 400Hz, 30%modulation
V
CC
= 8V, f
OSC
= 108.7MHz
Measured by Pin4, No signal input
V
CC
= 8V, Vin= 51dBµ
V
CC
= 8V, Vin= 67dBµ
V
CC
= 8V, Vin= 53dBµ
22
219
41
6
30
384
58
0.05
6.5
435
82
0.5
dB
mV
mV
V
V
Level · Diagram
50
40
30
20
10
0
Level (dB)
VCC=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
(dBµV)
AF
OUT
(dB)
400 20 8060
24.5
13.5
8.5
43.5 (max.)
20
15
10
5
0
–5
–10
–15
f
in
(MHz)
V
in
(dBµV)
98969088 9492 106108104102100
VCC=8V
f
in
=1kHz
Mod.=22.5kHz
IF : AN7256
Mix.
IF
OUT
0.01µF
MS3
080
IN
IFT
330Ω
IF–Amp.
16.0 (min.)
Practical Sensitivity (S/N=30dB)
Limiting Sensitivity
Residual Noise
![](/html/65/651e/651e10fcffef71245e0f3d0a97a48473d585919e652a1002b03eecf539154e58/bg3.png)
ICs for FM/AM Tuner
AN7280S
No Input
IF-Amp. Gain Adjustment
40
30
20
10
0
Pin13 Adjusting Resistance (
Ω)
Gain (dB)
0 1k ∞10K
VCC= 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
in
(dBµV)
2.20 1.41 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
tot
(mA )
V
ref
(V)
60 2 4 12108
Supply Voltage Change
110
100
60
50
20
10
0
V
CC
(V)
V
in
(dBµV)
86 7 109
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)
Total Gain (dB)
20 400–40 –20 10060 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)
AGC OUT V
t
(V)
SSC ON Level (V)
85 6 7 11 12109
SSC ON Level
V
t
IC for IF/DET
is normal temperature
Mixer+IF–Amp.
VCC= 8V
Temperature Characteristics
80
70
60
50
40
30
20
10
0
Ta (˚C)
V
in
(dBµV)
0–60 –40 –20 60 80 1004020
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
in
(dBµV)
20 400–40 –20 10060 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
Ω
27dB
Radj.= 0Ω
Amp. Gain Adjustment
with AGC
110
100
90
80
70
60
50
Pin6 Adjusting Resistance (
Ω)
AGC ON Level (dBµV)
0 1k ∞10K