AK4640_05 Datasheet, PDF (22/78 Pages) Asahi Kasei Microsystems – 16-Bit ΔΣ CODEC with MIC/HP/SPK-AMP

ASAHI KASEI
[AK4640]
OPERATION OVERVIEW
„ Master Clock Source
The AK4640 requires a master clock (MCKI). This master clock is input to the AK4640 by connecting a X’tal oscillator
to XTI and XTO pins or by inputting an external CMOS-level clock to the XTI pin or by inputting an external clock that
is greater than 50% of the DVDD level to the XTI pin through a capacitor.
When using a X’tal oscillator, there should be capacitors between XTI/XTO pins and DVSS. When using an external
clock, there are two choices: direct, where an external clock is input directly to the XTI pin and indirect, where the
external clock is input through a capacitor.
Master Clock
Status
PMXTL bit
X’tal Oscillator
(Figure 13)
Oscillator ON
1
Oscillator OFF
0
External Clock Direct Input (Figure 14) Clock is input to MCKI pin.
0
MCKI pin is fixed to “L”.
0
MCKI pin is fixed to “H”.
0
MCKI pin is Hi-Z
0
AC Coupling Input
(Figure 15) Clock is input to MCKI pin.
1
Clock isn’t input to MCKI pin.
0
Table 1. Master Clock Status by PMXTL bit and MCKPD bit
MCKPD bit
0
1
0
0/1
0
1
0
1
(1) X’tal Oscillator
XTI
MCKPD = "0"
C
25kΩ(typ)
C
PMXTL = "1"
XTO
AK4640
Figure 13. X’tal mode
Note: The capacitor values depend on the X’tal oscillator used. (C: typ. 10 ∼ 30pF)
MS0273-E-02
- 22 -
2005/04