TDA7421 Просмотр технического описания (PDF) - STMicroelectronics
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TDA7421 Datasheet PDF : 38 Pages
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TDA7421
ELECTRICAL CHARACTERISTICS (continued)
FM Section Global Performances
Refer to Evaluation Circuit and enclosed curves (S+N/N, THD)
- RF Input: fc = 98.1MHz, 75KHz dev., 1KHz mod.,60dBu
- Audio Output: BPF 20Hz - 20KHz
Symbol
S+N/N
THD
VO AF
US
Parameter
Signal to Noise Ratio
Total Harmonic Distortion
Audio Output Level
Usable Sensitivity
AGCrange Range AGC FM
Test Condition
deviation = 40KHz
antenna level at which
S+N/N=30dB
Min.
350
Typ.
68
0.3
400
4
Max.
450
Uni
dB
%
mVRMS
dBu
65
dB
FM Front-end Electrical Adjustments
Ref: FM Test Circuit measure VANTADJ and VRFADJ referred to VPLLOUT
Symbol
ANTADJ
MAX OFF
ANTADJ
STEP OFF
RFADJ
MAX OFF
RFADJ
STEP OFF
Parameter
Maximum FM Antenna Filter
Adjustment Voltage Offset
FM Antenna Filter Adjustment
Voltage Offset Step
Maximum FM RF Filter
Adjustment Voltage Offset
FM RF Filter Adjustment Voltage
Offset Step
Test Condition
VPLLOUT = 2.5V, ANA3-0 set to
1111
VPLLOUT = 2.5V, ANA3-0 set to
1001
VPLLOUT = 2.5V, RFA3-0 set to
1111
VPLLOUT = 2.5V, RFA3-0 set to
1001
Min. Typ. Max. Uni
21
25
27
%
2.8 3.6 4.4 %
21
25
27
%
2.8 3.6 4.4 %
FM Mixer
Ref: FM Test Circuit, measure input at VMIXFMIN, output at VMIXOUT
Symbol
ZIN,MIX
GMIX
IP3MIX
CP1MIX
Parameter
Single-ended input impedance
(pin 3, pin4)
Conversion Gain
3rd order intermodulation
distortion intercept point
1dB compression point
Test Condition
f = 100MHz
fIN = 98.1MHz
fd = 98.1MHz; fu1 = 98.2MHz;
fu2 = 98.3MHz;
fIN = 98.1MHz
Min. Typ. Max. Unit
12
Ω
21.8
dB
104
dBu
90
dBu
FM AGC
Ref: FM Test Circuit, measure input at VFMRFAGCIN, and VFMIFAGCIN, output at VFMAGCOUT
Symbol
Parameter
VRFAGCSTART Open Loop Rf Agc Starting Point
RINRFAGC Input Resistance
VIFAGCSTART Open Loop If Agc Starting Point
RINIFAGC Input Resistance
ROUTFMAGC Output Resistance
Test Condition
fRFAGCIN = 98.1MHz Value of
VFMRFAGCIN, at which
VFMAGCOUT = 4V
fIFAGCIN = 10.7MHz Value of
VFMIFAGCIN, at which
VFMAGCOUT = 4V
FAGC2-0 set to 111
Min. Typ. Max.
74 80 86
20
71 77 83
20
10
Unit
dBu
KΩ
dBu
KΩ
KΩ
6/38
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