AK4586 Datasheet, PDF (52/54 Pages) Asahi Kasei Microsystems – MULTI CHANNEL AUDIO CODEC WITH DIR

ASAHI KASEI
[AK4586]
1. Grounding and Power Supply Decoupling
The AK4586 requires careful attention to power supply and grounding arrangements. AVDD, DVDD and PVDD are
usually supplied from analog supply in system. Alternatively if AVDD, DVDD and PVDD are supplied separately, the
power up sequence is not critical. AVSS, DVSS and PVSS of the AK4586 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 AK4586 as possible, with the small value ceramic
capacitor being the nearest.
2. Voltage Reference Inputs
The voltage of VREFH sets the analog input/output range. VREFH pin is normally connected to AVDD with a 0.1µF
ceramic capacitor. VCOM is a signal ground of this chip. 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
VCOM pin. All signals, especially clocks, should be kept away from the VREFH and VCOM pins in order to avoid
unwanted coupling into the AK4586.
3. Analog Inputs
ADC inputs are single-ended and internally biased to VCOM. The input signal range scales with the supply voltage and
nominally 0.6 x VREFH Vpp (typ). The ADC output data format 2’s compliment. The DC offset is removed by the
internal HPF.
The AK4586 samples the analog inputs at 64fs. The digital filter rejects noise above the stop band except for multiples of
64fs. The AK4586 includes an anti-aliasing filter (RC filter) to attenuate a noise around 64fs.
4. Analog Outputs
The analog outputs are also single-ended and centered around the VCOM voltage. The input signal range scales with the
supply voltage and nominally 0.6 x VREFH Vpp. The DAC input data format is 2’s complement. The output voltage is a
positive full scale for 7FFFFFH(@24bit) and a negative full scale for 800000H(@24bit). The ideal output is VCOM
voltage for 000000H(@24bit). The internal analog filters remove most of the noise generated by the delta-sigma
modulator of DAC beyond the audio passband.
DC offsets on analog outputs are eliminated by AC coupling since DAC outputs have DC offsets of a few mV.
MS0097-E-01
- 52 -
2001/12