ak4563a AKM Semiconductor, Inc., ak4563a Datasheet - Page 37

• Manufacturer Part Number: ak4563a
• Description: Low Power 16bit 4ch Adc & 2ch Dac With Alc
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
[AK4563A]
1. Grounding and Power Supply Decoupling
The AK4563A requires careful attention to power supply and grounding arrangements. VA is usually supplied from
analog supply in system and VD is supplied from analog supply in system via a resistor of 10 ohms. Alternatively if VA
and VD are supplied separately, the power up sequence is not taken care. VT is a power supply pin to interface with the
external ICs and is supplied from digital supply in system. AGND and DGND of the AK4563A should 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 AK4563A as possible, with the
small value ceramic capacitor being the nearest.
2. Voltage Reference
The differential voltage between VREF and AGND sets the analog input/output range. VREF pin is normally connected
to VA with a 0.1 F ceramic capacitor. VCOM is output to 0.45 x VA(typ.) and is a signal ground of this chip. An
electrolytic capacitor 2.2 F parallel with a 0.1 F 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 VREF and VCOM pins in order to avoid unwanted coupling into the AK4563A.
3. Analog Inputs
The analog inputs are single-ended and the input resistance is 10k (typ) at MIC gain table and 125k (typ) at LINE gain
table. The input signal range scales with the VREF voltage and nominally 0.6 x VREF Vpp centered in the internal
common voltage. Usually the input signal is AC coupled with capacitor. The cut-off frequency is fc = (1/2 RC). The
AK4563A can accept input voltages to (VA-0.1) Vpp. The ADC output data format is 2’s complement. The output code
is 7FFFH(@16bit) for input above a positive full scale and 8000H(@16bit) for input below a negative fill scale. The ideal
code is 0000H(@16bit) with no input signal. The DC offset including ADC own DC offset removed by the internal HPF
(fc=3.7Hz@fs=48kHz).
The AK4563A samples the analog inputs at 64fs. The digital filter rejects noise above the stopband except for multiples of
64fs. The AK4563A includes an anti-aliasing filter (RC filter) to attenuate a noise around 64fs.
4. Analog Outputs
The analog outputs are single-ended and nominally 0.6 x VREF Vpp centered in the internal common voltage. The input
data format is 2’s complement. The output voltage is a positive full scale for 7FFFH(@16bit) and a negative full scale for
8000H(@16bit). The ideal output is the VCOM voltage for 0000H(@16bit). If the noise generated by the delta-sigma
modulator beyond the audio band would be the problem, the attenuation by external circuit is required.
DC offsets on analog outputs are eliminated by AC coupling since analog outputs have DC offsets of a few mV + VCOM
volrage.
MS0067-E-02
2004/12
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