AK5381 Datasheet, PDF (16/20 Pages) Asahi Kasei Microsystems – 24Bit 96kHz ΔΣ ADC

ASAHI KASEI
[AK5381]
1. Grounding and Power Supply Decoupling
The AK5381 requires careful attention to power supply and grounding arrangements. VA and VD are usually supplied
from the analog supply in the system. Alternatively if VA and VD are supplied separately, the power up sequence is not
critical. AGND and DGND of the AK5381 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 AK5381 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. 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 these pins. All signals, especially
clocks, should be kept away from the VCOM pin in order to avoid unwanted coupling into the AK5381.
3. Analog Inputs
The ADC inputs are single-ended and internally biased to the common voltage (50%VA) with 15kΩ(typ) 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 AK5381 samples the analog inputs at 64fs. The digital filter rejects noise above the stop band except for multiples of
64fs. The AK5381 includes an anti-aliasing filter (RC filter) to attenuate a noise around 64fs.
MS0200-E-02
- 16 -
2006/01