DA1017.002

29 May, 2002

4(6)

TYPICAL APPLICATION

Note 1: Ferrite Antenna and Crystal

The crystal as well as ferrite antenna frequencies are chosen according to the time signal system frequency.

DCF-77 transmitter frequency is 77.5 kHz. The ferrite antenna center frequency has to be tuned to 77.5 kHz.

The optimal crystal frequency is 77503 Hz but also 77500 Hz crystal can be used. The shunt capacitance of the

crystal should be as close as possible to internal shunt capacitance compensation capacitor of 0.75 pF for

optimal noise filtering.

Note 2: AGC and DEC Capacitors

The AGC and DEC capacitors should have low leakage currents due to very small 40 nA signal currents

through the capacitors. The insulation resistance of these capacitors should be higher than 70 M

Ω. Also probes

with at least 100 M

Ω impedance should be used for voltage probing of AGC and DEC pins.

AG C Am plifier

Dem odulator

&

Com parator

Pow er Supply/Biasing

RFI

DCF

QI

QO

VDD

AG C

DEC

VSS

Receiver

output

Ferrite-

Antenna

77503 Hz

+1.1V to +3.6V

PUP

470 nF

47 nF

PDN