[AK5357]
1. Grounding and Power Supply Decoupling
The AK5357 requires careful attention to power supply and grounding arrangements. Alternatively if VA and VD are
supplied separately, the power up sequence is not critical. AGND and DGND of the AK5357 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 AK5357 as possible, with the
small value ceramic capacitor being the nearest.
2. Voltage Reference
The voltage input to VA sets the analog input range. VCOM are 50%VA and normally connected to AGND with a 0.1μF
ceramic capacitor. A ceramic capacitor 0.47μF attached to VCOM pin 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 VCOM pin in
order to avoid unwanted coupling into the AK5357.
3. Analog Inputs
The ADC inputs are single-ended and internally biased to the common voltage (50%VA) with 20kΩ (typ@fs=48kHz)
resistance. The input signal range scales with the supply voltage and nominally 0.6xVA Vpp (typ). The ADC output data
format is 2’s complement. The DC offset is removed by the internal HPF.
The AK5357 samples the analog inputs at 64fs. The digital filter rejects noise above the stop band except for multiples of
64fs. The AK5357 includes an anti-aliasing filter (RC filter) to attenuate a noise around 64fs.
MS0294-E-03
2009/03
- 15 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
