U4224B TEMIC Semiconductors, U4224B Datasheet - Page 4

• Manufacturer Part Number: U4224B
• Description: Time Code Receiver
• Manufacturer: TEMIC Semiconductors

Q2A, Q2B
According to Q1A, Q1B a crystal is connected between
the pins Q2A and Q2B. It is used with the serial resonance
frequency of the time code transmitter (e.g. 60 kHz
WWVB, 77.5 kHz DCF or 40 kHz JG2AS). The equi-
valent parallel capacitor of the filter crystal is internally
compensated. The value of the compensation is about
0.7 pF.
PON
If PON is connected to GND
will be activated. The set-up time is typical 0.5s after
applying GND at this pin. If PON is connected to V
receiver will go into power down mode.
TCO
The digitized serial signal of the time code transmitter can
be directly decoded by a microcomputer. Details about
the time code format of several transmitters are described
separately.
The output consists of a PNP
should be taken into account that in the power down mode
(PON = high) TCO will be high.
U4224B
4 (17)
94 8383
94 8380
V
PON
Q2A
CC
,
*
the U 4224 B receiver IC
NPN push-pull-stage. It
GND
TCO
PON
V
Q2B
GND
CC
94 8373
CC
, the
An additional improvement of the driving capability may
be achieved by using a CMOS driver circuit or a NPN
transistor with pull-up resistor connected to the collector
(see figure KEIN MERKER). Using a CMOS driver this
circuit must be connected to V
Please note:
The signals and voltages at the pins REC, INT, FLA, FLB,
Q1A, Q1B, Q2A and Q2B cannot be measured by stan-
dard measurement equipment due to very high internal
impedances. For the same reason the PCB should be pro-
tected against surface humidity.
Design Hints for the Ferrite Antenna
The bar antenna is a very critical device of the complete
clock receiver. But by observing some basic RF design
knowledge, no problem should arise with this part. The IC
requires a resonance resistance of 50 k
can be achieved by a variation of the L/C-relation in the
antenna circuit. But it is not easy to measure such high
resistances in the RF region. It is much more convenient
to distinguish the bandwidth of the antenna circuit and
afterwards to calculate the resonance resistance.
Thus the first step in designing the antenna circuit is to
measure the bandwidth. Figure 4 shows an example for
the test circuit. The RF signal is coupled into the bar
antenna by inductive means, e.g. a wire loop. It can be
measured by a simple oscilloscope using the 10:1 probe.
The input capacitance of the probe, typically about 10 pF,
should be taken into consideration. By varying the
frequency of the signal generator, the resonance
frequency can be determined.
wire loop
RF - Signal
generator
77.5 kHz
pin16
TCO
100 k
C
res
TELEFUNKEN Semiconductors
W
Figure 1.
CC
10 k
w
.
10 M
Probe
10 : 1
94 8395 e
W
V
Rev. A3, 02-Apr-96
CC
W
W
TCO
to 200 k
Scope
94 7907 e
W
. This