U4221B
TELEFUNKEN Semiconductors
Rev. A1, 15-May-96
Preliminary Information
2 (12)
Pin Description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Symbol
IN2
IN1
GND
CAGC
CDEM
INA2
GND
OUTA1
V
CCD
NC
FSS
FSI
TCO
PON
GND
V
CCA
Function
Amplifier 1 - Input 2
Amplifier 1 - Input 1
Analog ground
Time constant of AGC
Low pass filter
Amplifier 2 input
Digital ground
Amplifier 1 output
Supply voltage (digital)
Not connected
Field strength select
Field strength indication
Time code output
Power ON/OFF control
Ground (substrate)
Supply voltage (analog)
2
3
4
7
8
1
5
6
16
15
13
12
14
11
10
9
IN2
CCA
V
CAGC
PON
IN1
GND
CDEM
INA2
GND
FSI
FSS
NC
OUTA1
CCD
V
U 4221 B
93 7507 e
GND
TCO
IN1, IN2
IN2 is connected to Pin 16 (V
CCA
). A ferrite antenna is
connected between IN1 and IN2. Q of antenna circuit
should be as high as possible, but the temperature
influence must be compensated. The resonant resistance
should be 200 k to 300 k for optimal sensitivity.
OUTA1, INA2
To achieve a high selectivity, a quartz resonator is
connected between the pins OUTA1
and INA2. It is used
with the serial resonance frequency of the time code
transmitter (e.g. 60 kHz WWVB, 77.5 kHz DCF). The
parasitic parallel capacitance C
0
of the quartz resonator
should be 0.5 pF to 1 pF.
CAGC
A control voltage derived from the field strength is
generated to control the amplifiers. The time constant of
this automatic gain control (AGC) is influenced by the
capacitor CAGC.
CDEM
After demodulation the signal is low pass filtered by the
capacitor CDEM.
PON
If PON is connected to V
CCD,
the U4221B receiver IC
will be activated. The set-up time is typical 2.5 s after ap-
plying V
CCD
at this pin. If PON is connected to GND, the
receiver will go into stop mode.
FSS
This pin is connected to GND, otherwise the field strength
indication FSI is disabled.
FSI
If the voltage at the input of amplifier 1 is higher than
about 5 V, FSI will be high.