ASAHI KASEI
[AK5392]
1. Grounding and Power Supply Decoupling
The AK5392 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 AK5392 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 fifferemtial 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 AK5392. 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 AK5392. 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 ±2.5Vpp(typ).The AK5392 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 AK5392 samples the analog inputs at 128fs(6.144MHz @fs=48kHz). 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 AK5392 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.
0188-E-01
1997/11
- 15 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
