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DA6180.001

27 December, 2006

TYPICAL APPLICATION (Continued)

Note 1: Crystals

The crystal as well as ferrite antenna frequencies are chosen according to the time-signal system (Table 1). The

external compensation capacitor should be matched similarly as well as possible with crystal’s shunt

capacitance. See Compensation Capacitance Options on table 2.

Table 1. Time-Signal System Frequencies

Time-Signal System

Location

Antenna Frequency

Recommended Crystal Frequency

DCF77

Germany

77.5 kHz

77.503 kHz

HGB

Switzerland

75 kHz

75.003 kHz

MSF

United Kingdom

60 kHz

60.003 kHz

WWVB

USA

60 kHz

60.003 kHz

JJY

Japan

40 kHz and 60 kHz

40.003 kHz and 60.003 kHz

BPC

China

68.5 kHz

68.505 kHz

Table 2 . Compensation Capacitance Options

Device

Crystal Description

MAS6180A1

0.75 pF

MAS6180A2

1.3 pF

MAS6180A5

For any crystals, external compensation capacitor

It should be noted that grounded crystal package has reduced shunt capacitance. This value is about 85% of

floating crystal shunt capacitance. For example crystal with 1 pF floating package shunt capacitance can have

0.85 pF grounded package shunt capacitance. PCB traces of crystal and external compensation capacitance

should be kept at minimum to minimize additional parasitic capacitance which can cause capacitance

mismatching.

In dual band receiver configuration the crystals can be connected in parallel thus external compensation

also possible to connect other crystal from QOP pin and the other crystal from QOM pin to common QI pin (figure

3). In this circuit configuration no external compensation capacitor is required since the crystals compensate

each other. The sensitivity of dual band receiver configuration will be lower than that of single band receiver

configuration since the noise band width of crystal filter with two parallel crystals is double.

Table 3 below presents some crystal manufacturers having suitable crystals for timesignal receiver application.

Table 3. Crystal Manufacturers and Crystal Types in Alphaphetical Order for Timesignal Receiver Application

Manufacturer

Crystal Type

Dimensions

Web Link

Citizen

CFV-206

ø 2.0 x 6.0

http://www.citizen.co.jp/tokuhan/quartz/

Epson Toyocom

C-2-Type

C-4-Type

ø 1.5 x 5.0

ø 2.0 x 6.0

http://www.epsontoyocom.co.jp/english/

KDS Daishinku

DT-261

ø 2.0 x 6.0

http://www.kds.info/index_en.htm

Microcrystal

MX1V-L2N

MX1V-T1K

ø 2.0 x 6.0

ø 2.0 x 8.1

http://www.microcrystal.com/

Seiko

Instruments

VTC-120

ø 1.2 x 4.7

http://www.sii-crystal.com