mc3371dtb ETC-unknow, mc3371dtb Datasheet - Page 12

• Manufacturer Part Number: mc3371dtb
• Description: Low Power Narrowband Fm If
• Manufacturer: ETC-unknow

trigger circuit such that the audio mute (Pin 14) is open or
connected to ground. If Pin 12 is pulled down to 0.9 V or
below by the noise or tone detector, Pin 14 is internally
shorted to ground. There is about 57 mV of hyteresis at
Pin 12 to prevent jitter. Audio muting is accomplished by
connecting Pin 14 to the appropriate point in the audio path
between Pin 9 and an audio amplifier. The voltage at Pin 14
should not be lower than –0.7 V; this can be assured by
connecting Pin 14 to the point that has no dc component.
12
An external positive bias to Pin 12 sets up the squelch
+
V CC = 4.0 Vdc
C9
10
8.2 H
L2
10.245
MHz
1st IF 10.7 MHz
0.01
C15
C1
91
from Input
R11
560
Front End
16
1
Oscillator
C10
68
Figure 11. Typical Application for MC3371 at 10.7 MHz
15
2
Squelch Trigger
with Hysteresis
L1
TKANS9443HM
6.8 H 6%
Mixer
51 k
C11
220
R1
14
3
CFU455D2
equivalent
RSSI Output
muRata
C17
0.1
or
13
MC3371 MC3372
4
12
5
C2
4.7
F
1.8 k
0.1
C3
D1
C12
0.1
Limiter
Amp
11
+
6
Filter
Amp
100 k
R4
1.0 k
1N5817 R5
510 k
R3
0.001
0.001
R9
be as a carrier level triggered squelch circuit, similar to the
MC3362/MC3363 FM receivers. In this case the meter
output can be used directly to trigger the squelch switch
when the RF input at the input frequency falls below the
desired level. The level at which this occurs is determined
by the resistor placed between the meter drive output
(Pin 13) and ground (Pin 15).
C5
C4
51 k
–
+
10
Another possible application of the squelch switch may
7
Demodulator
10 k
R2
4.7 k
4.7 k
C13
R7
0.1
560
Amp
53 k
AF
R6
10
9
8
R10
39 k
C14
0.1
3.3 k
R8
VR1 (Squelch Control)
10 k
MOTOROLA ANALOG IC DEVICE DATA
0.022
C7
VR2
10 k
0.22
C8
T2: Toko
2A6597 HK (10 mm)
or
7MC–8128Z (7 mm)
AF Out
to Audio
Power Amp