AK4950 Datasheet, PDF (91/106 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/SPK/Cap-less VIDEO-AMP & mini DSP

[AK4950]
1. Grounding and Power Supply Decoupling
The AK4950 requires careful attention to power supply and grounding arrangements. A ceramic capacitor of 0.1μF or
more should be connected to between AVDD and VSS1/3/4. If AVDD and TVDD are supplied separately, the power-up
sequence is not critical. VSS1, VSS2, VSS3 and VSS4 of the AK4950 must be connected to the analog ground plane.
System analog ground and digital ground should be wired separately and connected together as close as possible to where
the supplies are brought onto the printed circuit board. Decoupling capacitors must be as near to the AK4950 as possible,
with the small value ceramic capacitor being the nearest.
2. Internal Regulated Voltage Power Supply
VCOM is a signal ground of this chip. A 2.2μF electrolytic capacitor in parallel with a 0.1μF ceramic capacitor 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, should be kept away from the VCOM pin in order to avoid unwanted coupling into the
AK4950.
3. Analog Inputs
The Mic and Line inputs supports single-ended. The input signal range scales with nominally at typ. 0.9 x 2.3Vpp (@
MGAIN = 0dB), centered around the internal signal ground (typ. 1.15V). Usually the input signal is AC coupled with a
capacitor. The cut-off frequency is fc = 1/(2πRC). The AK4950 can accept input voltages from VSS1 to AVDD.
6. 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 data). The
common voltage of stereo lineout is 1.35V or 1.43V (typ) and the speaker output is centered on AVDD/2 (typ).
MS1320-E-00
- 91 -
2011/10