AK4645 Datasheet, PDF (84/96 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/HP-AMP

ASAHI KASEI
[AK4645]
1. Grounding and Power Supply Decoupling
The AK4645 requires careful attention to power supply and grounding arrangements. AVDD, DVDD, TVDD and HVDD
are usually supplied from the system’s analog supply. If AVDD, DVDD, TVDD and HVDD are supplied separately, the
power-up sequence is not critical. AVSS and HVSS of the AK4645 should be connected to the 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 AK4645 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 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
AK4645.
3. Analog Inputs
The Mic, Line and MIN inputs are single-ended. The input signal range scales with nominally at 0.06 x AVDD Vpp(typ)
@MGAIN1-0 bits = “01”, 0.03 x AVDD Vpp(typ) @MGAIN1-0 bits = “10”, 0.015 x AVDD Vpp(typ) @MGAIN1-0
bits = “11” or 0.6 x AVDD Vpp(typ) @MGAIN1-0 bits = “00” for the Mic/Line input and 0.6 x AVDD Vpp (typ) for the
MIN input, centered around the internal common voltage (0.45 x AVDD). Usually the input signal is AC coupled using a
capacitor. The cut-off frequency is fc = (1/2πRC). The AK4645 can accept input voltages from AVSS 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 7FFFH(@16bit) and
a negative full scale for 8000H(@16bit). Stereo Line Output is centered at 0.45 x AVDD. The Headphone-Amp output is
centered at HVDD/2.
MS0543-E-00
- 84 -
2006/09