ASAHI KASEI
[AK5353]
1. Grounding and Power Supply decoupling
The AK5353 requires careful attention to power supply and grounding arrangements. VA and VD are usually supplied
from analog supply in system. Alternatively if VA and VD are supplied separately, the power up sequence is not critical.
AGND and DGND of the AK5353 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 AK5353 as possible, with the small value ceramic capacitor being the nearest.
2. On-chip voltage reference
The voltage input to VA sets the analog input range. VREF and VCOM are 55%VA and normally connected to VA with
a 0.1uF ceramic capacitor. An electrolytic capacitor 10uF parallel with a 0.1uF ceramic capacitor attached to VREF and
VCOM pins eliminates the effects of high frequency noise. No load current may be drawn from these pins. All signals,
especially clocks, should be kept away from the VREF and VCOM pins in order to avoid unwanted coupling into the
AK5353.
3. Analog Inputs
The ADC inputs are single-ended and internally biased to the common voltage (55%VA) with 100kΩ (typ) resistance.
The input signal range scales with the supply voltage and nominally 0.6xVA Vpp. The ADC output data format is 2 s
complement. The output code is 7FFFFFH(@24bit) for input above a positive full scale and 800000H(@24bit) for input
below a negative full scale. The ideal code is 000000H(@24bit) with no input signal. The DC offset is removed by the
internal HPF.
The AK5353 samples the analog inputs at 64fs. The digital filter rejects noise above the stop band except for multiples of
64fs. A simple RC filter (fc=150kHz) may be used to attenuate any noise around 64fs and most audio signals do not have
significant energy at 64fs.
M0067-E-00
1999/06
- 15 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
