AK5720 Datasheet, PDF (22/25 Pages) Asahi Kasei Microsystems – 96kHz 24-Bit ADC

[AK5720]
1. Grounding and Power Supply Decoupling
The AK5720 requires careful attention to power supply and grounding arrangements. Alternatively if VA and
VD are supplied separately, the power up sequence is not critical. VSS of the AK5720 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 AK5720 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 is 50%VA and used as the common voltage of
analog signals. The VCOM pin is connected to VSS. A 0.47F ceramic capacitor should be connected as close
to the VCOM pin as possible between VSS and the VCOM pin. 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 AK5720.
3. Analog Inputs
The ADC inputs are single-ended and internally biased to the common voltage (50%VA) with 41k
(typ@fs=48kHz) resistance. The input signal range scales with the supply voltage and nominally 0.6×VA Vpp
(typ). The ADC output data format is 2’s complement. The internal HPF removes the DC offset (includes the
DC offset that is caused by the ADC).
The AK5720 samples the analog inputs at 64fs. The digital filter rejects noise above the stop band except for
multiples of 64fs. The AK5720 includes an anti-aliasing filter (RC filter) to attenuate a noise around 64fs.
4. External Resistor of the CKS pin
The external resistor of the CKS pin should be close as possible to the pin and kept away from the signal lines
to prevent noises into the CKS pin.
MS1641-E-02
- 22 -
2014/12