
ASAHI KASEI
[AK4628A]
MS0385-E-00
2005/02
- 38 -
Analog Ground
Digital Ground
System
Controller
T
SDOS
1
2
3
4
5
6
7
8
9
11
10
I2C
BICK
LRCK
SDTI1
SDTI2
SDTI3
SDTO
DAUX
DFS0
RIN
L
D
M
D
A
V
DZF2/OVF
A
V
S
1
1
1
1
1
1
1
1
2
2
2
D
D
T
D
T
C
C
L
R
LIN
NC
TST2
ROUT1
LOUT1
ROUT2
LOUT2
ROUT3
LOUT3
AK4628A
P
D
P
SMUTE
33
32
31
30
29
28
27
26
25
23
24
4
4
4
4
4
3
3
3
3
3
3
Figure 26. Ground Layout
Note: AVSS and DVSS must be connected to the same analog ground plane.
1. Grounding and Power Supply Decoupling
The AK4628A requires careful attention to power supply and grounding arrangements. AVDD and DVDD are usually
supplied from analog supply in system. Alternatively if AVDD and DVDD are supplied separately, the power up
sequence is not critical.
AVSS and DVSS of the AK4628A must be connected to analog ground plane.
System analog
ground and digital ground should be connected together near to where the supplies are brought onto the printed circuit
board. Decoupling capacitors should be as near to the AK4628A as possible, with the small value ceramic capacitor being
the nearest.
2. Voltage Reference Inputs
The voltage of VREFH sets the analog input/output range. VREFH pin is normally connected to AVDD with a 0.1μF
ceramic capacitor. VCOM is a signal ground of this chip. An electrolytic capacitor 2.2μF parallel with a 0.1μF ceramic
capacitor attached to VCOM pin eliminates the effects of high frequency noise. No load current may be drawn from
VCOM pin. All signals, especially clocks, should be kept away from the VREFH and VCOM pins in order to avoid
unwanted coupling into the AK4628A.
3. Analog Inputs
ADC inputs are single-ended and internally biased to VCOM. The input signal range scales with the supply voltage and
nominally 0.62 x VREFH Vpp (typ)@fs=48kHz. The ADC output data format 2’s compliment. The DC offset is removed
by the internal HPF.
The AK4628A samples the analog inputs at 64fs. The digital filter rejects noise above the stop band except for multiples
of 64fs. The AK4628A includes an anti-aliasing filter (RC filter) to attenuate a noise around 64fs.