AK2347B Datasheet, PDF (31/34 Pages) Asahi Kasei Microsystems – Two-way Radio Audio & Sub-Audio Processor

ASAHI KASEI
[AK2347B]
7) Oscillator circuit
When the built-in oscillator circuit is to be used, connect a 3.6864MHz or 3.579545MHz crystal
oscillator and a capacitor as shown in Fig. 6. 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 an external clock is to be supplied, connect the clock line as shown in Fig. 7 or Fig. 8
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. 7. If the input clock amplitude (p-p value) is between 0.2V and 1.0V,
connect the clock signal as shown in Fig. 8.
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 ratings.
XIN
22pF
1MΩ
XOUT
3.6864MHz
3.579545MHz
22pF
LSI
Fig. 6
External Clock IN
14 _XIN
3.6864MHz
3.579545MHz
15 XOUT
LSI
Fig. 7
XIN
0.01uF
1MΩ
XOUT
LSI
Fig. 8
External Clock IN
3.6864MHz
3.579545MHz
MS1419-E-00
- 31 -
2012/05