MAS9178A1TB00.01 MAS [Micro Analog systems], MAS9178A1TB00.01 Datasheet - Page 5

• Manufacturer Part Number: MAS9178A1TB00.01
• Description: AM Receiver IC
• Manufacturer: MAS [Micro Analog systems]

TYPICAL APPLICATION (Continued)
Figure 3
Note 1: Crystal
The crystal as well as ferrite antenna frequencies are chosen according to the time-signal system (Table 1). The
crystal shunt capacitance C
compensation capacitor C
MAS9178A1. MAS9178A5 does not have internal compensation capacitance C
compensation capacitor C
have equal value with crystal’s effective shunt capacitance C
should be used when fixed 0.875 pF compensation capacitance of MAS9178A1 does not match well with used
crystal’s shunt capacitance.
It should be noted that grounded crystal package has reduced shunt capacitance. This value is about 85% of
floating crystal 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
capacitor value C
is 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.
Time-Signal System
DCF77
MSF
WWVB
JJY
Table 1
Antenna
Ferrite
Frequency
Dual band application circuit of external compensation capacitance version MAS9178A5.
Time-Signal System Frequencies
Selection
Antenna
C_EXT
must be sum of two crystals’ shunt capacitances. Instead of parallel crystal connection it
Germany
United Kingdom
USA
Japan
Location
C_EXT
C
=0.875 pF of MAS9178A1. External compensation pad QOM is unconnected in
0
. It must be connected between pins QOM and QI (see figure 2). C
should be matched as well as possible with the internal shunt capacitance
RFM
RFP
1.4 V
VDD
Power Supply/Biasing
QOP
AGC Amplifier
Note 1
VSS
Antenna Frequency
77.5 kHz
60 kHz
40 kHz and 60 kHz
60 kHz
Power Down /
Fast Startup
PDN
QI
Control
Note 3
QOM
0
. External compensation version MAS9178A5
C
10 µF
for AGC on/hold
AGC
AGC
Recommended Crystal Frequency
77.503 kHz
60.003 kHz
60.003 kHz
40.003 kHz and 60.003 kHz
Demodulator
Note 2
Comparator
Optional
Control
Note 4
+
C
&
DEC
AON
and it requires use of external
C
47 nF
OUT
DEC
10 Dec, 2003
DA9178.001
C_EXT
Receiver
Output
should
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