AK5383 Datasheet, PDF (15/20 Pages) Asahi Kasei Microsystems – Enhanced Dual bit 96 kHz 24-bit ADC

ASAHI KASEI
[AK5383]
1. Grounding and Power Supply Decoupling
The AK5383 requires careful attention to power supply and grounding arrangements. Analog ground and digital ground
should be separate and connected together near to where the supplies are brought onto the printed circuit board.
Decoupling capacitors should be as near to the AK5383 as possible, with the small value ceramic capacitor being the
nearest.
2. On-chip voltage reference and VCOM
The reference voltage for A/D converter is a differential voltage between the VREFL/R output voltage and the GNDL/R
input voltage. The GNDL/R are connected to AGND and a 10uF electrolytic capacitor parallel with a 0.1uF ceramic
capacitor between the VREFL/R and the GNDL/R eliminate the effects of high frequency noise. Especially a ceramic
capacitor should be as near to the pins as possible. And all digital signals, especially clocks, should be kept away from the
VREFL/R pins in order to avoid unwanted coupling into the AK5383. No load current may be taken from the VREFL/R
pins.
VCOM is a common voltage of the analog signal. In order to eliminate the effects of high frequency noise, a 0.22uF
ceramic capacitor should be connected as near to the VCOM pin as possible. And all signals, especially clocks, should be
kept away from the VCOM pin in order to avoid unwanted coupling into the AK5383. No load current may be drawn from
the VCOM pin.
3. Analog Inputs
Analog signal is differentially input into the modulator via the AIN+ and the AIN- pins. The input voltage is the difference
between AIN+ and AIN- pins. The full-scale of each pin is nominally ± 2.45Vpp(typ). The AK5383 can accept input
voltages from AGND to VA. 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 offset calibration.
The AK5383 samples the analog inputs at 128fs(6.144MHz @fs=48kHz,DFS="L"). The digital filter rejects noise above
the stop band except for multiples of 128fs. A simple RC filter may be used to attenuate any noise around 128fs and most
audio signals do not have significant energy at 128fs.
The AK5383 accepts +5V supply voltage. Any voltage which exceeds the upper limit of VA+0.3V and lower limit of
AGND-0.3V and any current beyond 10mA for the analog input pins(AIN+ /-) should be avoided. Excessive currents to the
input pins may damage the device. Hence input pins must be protected from signals at or beyond these limits. Use caution
specially in case of using ±15V in other analog circuits.
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