AK4649 Datasheet, PDF (81/96 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/SPK-AMP

[AK4649]
1. Grounding and Power Supply Decoupling
The AK4649 requires careful attention to power supply and grounding arrangements. AVDD, DVDD and SVDD are
usually supplied from the system’s analog supply. If AVDD, DVDD and SVDD are supplied separately, the power-up
sequence is not critical. VSS1, VSS2 and VSS3 of the AK4649 must be connected to the analog ground plane. System
analog ground and digital ground must be connected together near to where the supplies are brought onto the printed
circuit board. Decoupling capacitors must be as near to the AK4649 as possible, with the small value ceramic capacitor
being the nearest.
2. Voltage Reference
VCOM is a signal ground of this chip. A 2.2μF electrolytic capacitor in parallel with a 0.1μF ceramic capacitor nust be
attached to the VCOM pin eliminates the effects of high frequency noise. No load current may be drawn from the VCOM
pin. All signals, especially clocks, must be kept away from the VCOM pin in order to avoid unwanted coupling into the
AK4649.
3. Analog Inputs
The MIC and Line inputs are single-ended. The inputs signal range scales with nominally at typ. 0.07 x AVDD Vpp (@
MGAIN = +20dB) and typ. 0.7 x AVDD Vpp (@ MGAIN = 0dB), centered around the internal common voltage (typ. 0.5
x AVDD). Usually the input signal is AC coupled using a capacitor. The cut-off frequency is fc = 1/ (2πRC). The AK4649
can accept input voltages from VSS1 to AVDD.
4. Analog Outputs
The input data format for the DAC 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). Stereo Line
Output is centered at typ. 0.5 x AVDD. The Headphone-Amp and Speaker-Amp outputs are centered at typ. 0.5 x SVDD.
MS1023-E-01
- 81 -
2010/08