AK2363 Datasheet, PDF (31/33 Pages) Asahi Kasei Microsystems – Radio Signaling LSI

ASAHI KASEI
[AK2363]
6) Oscillator circuit
When the built-in oscillator circuit is to be used, connect a 3.6864MHz crystal oscillator, a resistor, and
capacitors as shown in Fig. 1. The internal buffer is designed to allow stable oscillation of a crystal
oscillator for the electrical equivalent circuitry with a resonance resistance of 150Ω (Max.) and a shunt
capacitance of 5pF (Max.).
It is recommended that 22pF capacitors be connected externally so that the total load capacitance is
16pF (5pF + 22pF//22pF) or less. Place the oscillator, resistor, and capacitors as close to the XIN and
XOUT pins as possible.
When a clock signal is supplied externally, not only 3.6864MHz but also 7.3728MHz (twice higher
than 3.6864MHz), 11.0592MHz (three times higher than 3.6864MHz), and 14.7456MHz (four times
higher than 3.6864MHz) are supported. However, the internal frequency must always be set to
3.6864MHz by selecting division by 2, 3, or 4 for the divider in the subsequent stage. Connect the
clock signal as shown in Fig. 2 or Fig. 3 according to the clock amplitude level.
The circuit in the first stage of the XIN pin has a constant threshold voltage (0.8V). Therefore, if
the high level of the input clock is 1.5V or higher and the low level is 0.4V or lower, connect the
clock signal as shown in Fig. 2. If the input clock amplitude (p-p value) is 0.2V or higher and 1.0V
or lower, connect the clock signal as shown in Fig. 3.
When the clock is to be shared with peripheral ICs, the clock must be input and output on the XIN pin.
The clock amplitude must not exceed the absolute maximum rating.
XIN
22pF
1MW
XOUT
3.6864MHz
22pF
LSI
Fig. 1
15 XIN
16 XOUT
LSI
Fig. 2
External Clock IN
3.6864MHz
7.3728MHz
11.0592MHz
14.7456MHz
XIN
0.01uF
1MW
XOUT
LSI
Fig. 3
External Clock IN
3.6864MHz
7.3728MHz
11.0592MHz
14.7456MHz
MS0583-E-01
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2008/06