MC3362 查看數據表（PDF） - Motorola => Freescale
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MC3362 Datasheet PDF : 8 Pages
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MC3362
Figure 11. Component Placement View
Showing Crystal Oscillator Circuit
Figure 11A. LC Oscillator Component View
8
.47 µH
.1
1.
100K
2
120p
10.245MHz
XT
CF
455KHz .1
.1
.1
51K
2
10K
2
68K
10K
3
7
.68
µH
.68
µH
39 MHz
XT
3
1
1
4
TOKO
55VLC06379GT
5
3
1
METER
DRIVE
DATA
REC. AUDIO
NOTES: 1. Recovered Audio components may be deleted when using
data output.
2. Carrier Detect components must be deleted in order to obtain
linear Meter Drive output. With these components in place the
Meter Drive outputs serve only to trip the Carrier Detect indicator.
3. Data Output components should be deleted in applications
where only audio modulation is used. For combined audio/data
applications, the 0.047 µF coupling capacitor will add distortion
to the audio, so a pull–down resistor at pin 13 may be required.
4. Use Toko 7MC81282 Quadrature coil.
.41 µH
5. Meter Drive cannot be used simultaneously with Carrier Detect output.
For analog meter drive, remove components labelled ″2″ and measure
meter current (4–12 µA) through ammeter to VCC.
6. Either type of oscillator circuit may be used with any output circuit
configuration.
7. LC Oscillator Coil: Coilcraft UNI 10/42 10.5 turns, 0.41 µH Crystal
Oscillator circuit: trim coil, 0.68 µH. Coilcraft M1287–A.
8. 0.47 H, Coilcraft M1286–A. Input LC network used to match first mixer
input impedance to 50 Ω .
CIRCUIT DESCRIPTION
The MC3362 is a complete FM narrowband receiver from
antenna input to audio preamp output. The low voltage dual
conversion design yields low power drain, excellent
sensitivity and good image rejection in narrowband voice and
data link applications.
In the typical application (Figure 1), the first mixer
amplifies the signal and converts the RF input to 10.7 MHz.
This IF signal is filtered externally and fed into the second
mixer, which further amplifies the signal and converts it to a
455 kHz IF signal. After external bandpass filtering, the low IF
is fed into the limiting amplifier and detection circuitry. The
audio is recovered using a conventional quadrature detector.
Twice–IF filtering is provided internally.
The input signal level is monitored by meter drive circuitry
which detects the amount of limiting in the limiting amplifier.
The voltage at the meter drive pin determines the state of the
carrier detect output, which is active low.
APPLICATIONS INFORMATION
The first local oscillator can be run using a free–running
LC tank, as a VCO using PLL synthesis, or driven from an
external crystal oscillator. It has been run to 190 MHz.* A
buffered output is available at Pin 20. The second local
oscillator is a common base Colpitts type which is typically
run at 10.245 MHz under crystal control. A buffered output is
available at Pin 2. Pins 2 and 3 are interchangeable.
The mixers are doubly balanced to reduce spurious
responses. The first and second mixers have conversion
gains of 18 dB and 22 dB (typical), respectively, as seen in
Figure 6. Mixer gain is stable with respect to supply voltage.
For both conversions, the mixer impedances and pin layout
are designed to allow the user to employ low cost, readily
available ceramic filters. Overall sensitivity and AM rejection
are shown in Figure 7. The input level for 20 dB (S + N)/N is
0.7 µV using the two–pole post–detection filter pictured.
* If the first local oscillator (Pins 21 and/or 22) is driven from a
strong external source (100 mVrms), the mixer can be used to
over 450 MHz.
MOTOROLA ANALOG IC DEVICE DATA
5
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