AK2346B Datasheet, PDF (28/31 Pages) Asahi Kasei Microsystems – Two-way Radio Audio Processor

ASAHI KASEI
[AK2346B]
7) Clock Generation
The clock source can be chosen either internally generating with crystal oscillator or externally
supplied.
Figure 1 shows internally generating using the on-chip amplifier, a crystal oscillator, resistor and
capacitors. AK2346B is designed to get a stable oscillation for the electrical equivalent circuitry of
quartz crystal unit: resonance resistance≤150Ω(Max.) and shunt capacitance≤5pF(Max.).
Recommended external capacitance is 22pF due not to exceed the load capacitance≤16pF
(5pF+22pF//22pF). These external components are mounted close to the device pins.
Figure 2 and 3 show externally supplied example of clock generation. The first gate of XIN pin is
composed of non-voltage-tracking type amplifier that threshold level is 0.8V.
In case the high level of input clock amplitude equals or greater than 1.5V and the low level
equals or smaller than 0.5V, recommended configuration is Figure 2.
In case clock peak-to-peak level equals or greater than 0.2V and equals or smaller than 1.0V,
recommended configuration is Figure 3.
Please be careful not to let the clock amplitude exceed the absolute maximum ratings.
XIN
22pF
External Clock IN
1MΩ
3.6864MHz
XOUT
22pF
LSI
Figure 1
16 _XIN
3.6864MHz
15 XOUT
LSI
Figure 2
XIN
0.01uF
1MΩ
XOUT
LSI
Figure 3
External Clock IN
3.6864MHz
MS1409-E-00
- 28 -
2012/05