U2510B Datasheet, PDF (11/15 Pages) ATMEL Corporation – All-Band AM/FM Receiver and Audio Amplifier

U2510B
The alignment of the LC-discriminator circuit should be
done with little or no effect on the AFC function. This can
be realized by:
–
switching Pin 21 to open-circuit
–
connecting Pin 1 to a voltage source of 2 V
–
using a low signal level for alignment.
In general, ceramic discriminator devices can be used,
too. In this case, the effect of unavoidable spreads in the
frequency characteristics of these case ceramic devices in
conjunction with the IC characteristic has to be consid-
ered. For example, mismatches of the characteristics
between selectivity block and FM discriminator will lead
to an increased signal-to-noise ratio at low signal level as
well as to a higher demodulation distortion level or to an
asymmetrical AFC.
Application Circuits
Antenna
FM AM
L₃
C₂
C₁₆
2 pF
33 pF
C₁₈
C₁₇
33 pF
33 pF
L₄
C₃
22 pF
C₄
T₂
L₁ L₂
27 pF
C₇ C₆
4.7 µF 22 nF
AM IFT
14 13 12 11 10
9
8
7
6
5
T₁
455 kHz
CF₁
U2510B
C₅
Volume
6 pF
P₁
50 kΩ
T₄
C_{25 100 pF}
C₈
4.7 µF
4
3
C₂₄
18 pF
2
1
15 16 17 18 19 20 21 22 23 24 25 26 27 28
R₁
390 Ω
CF₂
10.7 MHz
C₉
10 nF
C₁₅
220 µF
100 nF
S₂
AM
FM
C₁₀
C₁₁
4.7 µF 10 nF
C₁₄
C₁₂
C₁₃
4.7 µF 470 µF
Z=8Ω
Figure 17. Application circuit (low cost)
S₁
V_S
13915
Rev. A3, 23-Feb-01
11 (15)