DA9081.006
1 August, 2005
TYPICAL APPLICATION (Continued)
Note 1: Crystals
The crystals as well as ferrite antenna frequencies are chosen according to the time-signal system (Table 2).
The crystal shunt capacitance C
0
should be matched as well as possible with the internal shunt capacitance
compensation capacitor C
C
of MAS9081. See Compensation Capacitance Options on table 3.
Table 2
Time-Signal System Frequencies
Time-Signal System
Location
DCF77
HGB
MSF
WWVB
JJY
BPC
Germany
Switzerland
United Kingdom
USA
Japan
China
Antenna Frequency
77.5 kHz
75 kHz
60 kHz
60 kHz
40 kHz and 60 kHz
68.5 kHz
Recommended Crystal Frequency
77.503 kHz
75.003 kHz
60.003 kHz
60.003 kHz
40.003 kHz and 60.003 kHz
68.505 kHz
Table 3
Compensation Capacitance Options
Device
C
C
Crystal Description
MAS9081A1
MAS9081A3
MAS9081A4
MAS9081A5
0.75 pF
1.25 pF
1.5 pF
3.875 pF
For low C
0
crystal
For high C
0
crystal
For high C
0
crystal
For any crystal (over compensated, requires external capacitors)
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 1pF floating package shunt capacitance can have
0.85pF 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.
Highest frequency crystal is connected to crystal output pin 1 (QO1). Lowest frequency crystal is connected to
crystal output pin 2 (QO2). The other pin of both crystals is connected to common crystal input pin QI.
Table 4 below presents some crystal manufacturers having suitable crystals for timesignal receiver application.
Table 4.
Crystal Manufacturers and Crystal Types in Alphaphetical Order for Timesignal Receiver Application
Manufacturer
Crystal Type
Dimensions
Web Link
Citizen
Epson
KDS Daishinku
Microcrystal
Seiko
Instruments
CFV-206
C-2-Type
C-4-Type
DT-261
MX1V-L2N
MX1V-T1K
VTC-120
ø 2.0 x 6.0
ø 1.5 x 5.0
ø 2.0 x 6.0
ø 2.0 x 6.0
ø 2.0 x 6.0
ø 2.0 x 8.1
ø 1.2 x 4.7
http://www.citizen.co.jp/tokuhan/quartz/
http://www.epsondevice.com/e/
http://www.kdsj.co.jp/english.html
http://www.microcrystal.com/
http://speed.sii.co.jp/pub/compo/quartz/topE.jsp
Note 2: AGC Capacitor
The AGC and DEC capacitors must have low leakage currents due to very small signal currents through the
capacitors. The insulation resistance of these capacitors should be at minimum 100 MΩ. Also probes with at
least several 100 MΩ impedance should be used for voltage probing of AGC and DEC pins. DEC capacitor can
be low leakage chip capacitor.
6 (12)
MAS [ MICRO ANALOG SYSTEMS ]
