SE567D Просмотр технического описания (PDF) - Philips Electronics
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SE567D Datasheet PDF : 13 Pages
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Philips Semiconductors Linear Products
Tone decoder/phase-locked loop
Product specification
NE/SE567
C2
+
130
fO
m
F
C3
+
260
fO
m
F
In cases where turn-off time can be sacrificed to achieve fast
turn-on, the optional sensitivity adjustment circuit can be used to
move the quiescent C3 voltage lower (closer to the threshold
voltage). However, sensitivity to beat frequencies, noise and
extraneous signals will be increased.
OPTIONAL CONTROLS (Figure 3)
The 567 has been designed so that, for most applications, no
external adjustments are required. Certain applications, however,
will be greatly facilitated if full advantage is taken of the added
control possibilities available through the use of additional external
components. In the diagrams given, typical
values are suggested where applicable. For best results the
resistors used, except where noted, should have the same
temperature coefficient. Ideally, silicon diodes would be
low-resistivity types, such as forward-biased transistor base-emitter
junctions. However, ordinary low-voltage diodes should be adequate
for most applications.
250
0.5k 0.9k 1.4k 1.9k 2.5k 3.2k 4.0k
200
10k
150
20k
100
100k
50
R
0
02 4
6 8 10 12 14 16
DETECTION BAND — % OF fO
PIN 2
567
V+
RA
50k
RB
R + RA )
RBRC
RB ) RC
C2
RC
OPTIONAL SILICON
DIODES FOR
TEMPERATURE
COMPENSATION
NOTE:
ǒ Ǔ ǒ Ǔ 130 10k ) R
1300 10k ) R
fO
R
t C2 t
fO
R
Adjust control for symmetry of detection band edges
about fO.
Figure 6. BW Reduction
SENSITIVITY ADJUSTMENT (Figure 3)
When operated as a very narrow-band detector (less than 8
percent), both C2 and C3 are made quite large in order to improve
noise and out-band signal rejection. This will inevitably slow the
response time. If, however, the output stage is biased closer to the
threshold level, the turn-on time can be
improved. This is accomplished by drawing additional current to
terminal 1. Under this condition, the 567 will also give an output for
lower-level signals (10mV or lower).
By adding current to terminal 1, the output stage is biased further
away from the threshold voltage. This is most useful when, to obtain
maximum operating speed, C2 and C3 are made very small.
Normally, frequencies just outside the detection band could cause
false outputs under this condition. By desensitizing the output stage,
the out-band beat notes do not feed through to the output stage.
Since the input level must
V+
V+
RA
10k
UNLATCH
RL
567 8
1
Rf
CA
C3 20k
V+
UNLATCH
V+
RL
567 8
1
Rf
20k
C3
NOTE:
CA prevents latch-up when power supply is turned on.
Figure 7. Output Latching
April 15, 1992
411
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