AK2125 Datasheet, PDF (6/6 Pages) List of Unclassifed Manufacturers – Receiver/ Demodulator for time code signals transmitted by the transmitter DCF77( Germany) ,MSF(UK), or WWVB(USA)

Output current I_OH ( V_R = 6 V )
Output current I_OL ( U_R = 6 V )
Output voltage V_OL
( I_OL= 15 µA)
min.
typ.
60
200
20
max.
10
200
unit
µA
µA
mV
Application Hints
1. RF Component
An inductive coupling of signals occurs between E1 and AP.
The output A2, with an impedance of 7.5 kΩ, has an inverted output signal ca. 5 dB lower than A1. The filter band
width of the quartz filter between A1 and E3 should be set to 20...25 Hz with a series resistance of 330 kΩ.The
associated signal attenuation of ca. 12 dB is also desirable when other filter cofigurations are applied.
2. Demodulator, Control time constants
The demodulated time signal impulses are available at CD. The time constant is CD _* 70 kΩ. Regulated voltage is
attained at the CR pin, whereby the control-time constant is determined by an internal decharging circuit and CR.
The control rate can be increased by means of an external resistor parallel to CR.
To reduce oscillating overdrive the additional connection with a series resistor of 680 Ω on the CR is
recommended.
3. Receiver circuit
The optimal supply voltage is 1.4 V. At applications with a voltage supply above 1.4 V it is better to connect V_CC
with a bias resistor so that there is about 1.4 V, whereby there is a simultaneous dynamic decoupling to other
components. The output is able to bear load resistance with working voltages of up to 5.25 V independent of V_CC.
It is therefore advantageous to block the V_CC - pin with a capacitor > 4.7 µF.
The usual RF-technical aspects are valid for the board layout, whereby special attention should be given to the
fact that between A and E3 the greatest possible area is intended for purposes of shielding.