AK4951AEN Datasheet, PDF (89/105 Pages) Asahi Kasei Microsystems – 24bit Stereo CODEC with MIC/HP/SPK-AMP

[AK4951A]
1. Grounding and Power Supply Decoupling
The AK4951A requires careful attention to power supply and grounding arrangements. AVDD and SVDD
are usually supplied from the system’s analog supply, and DVDD and TVDD are supplied from the
system’s digital power supply. If AVDD, DVDD, TVDD and SVDD are supplied separately, the power-up
sequence is not critical. The PDN pin should be held “L” when power supplies are tuning on. The PDN pin
is allowed to be “H” after all power supplies are applied and settled.
To avoid pop noise on headphone output and line output when power up/down, the AK4951A should be
operated along the following recommended power-up/down sequence.
1) Power-up
- The PDN pin should be held “L” when power supplies are turning on. The AK4951A can be reset by
keeping the PDN pin “L” for 200ns or longer after all power supplies are applied and settled.
2) Power-down
- Each of power supplies can be powered OFF after the PDN pin is set to “L”.
VSS1, VSS2 and VSS3 of the AK4951A should 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 should be as close
the power supply pins as possible. Especially, the small value ceramic capacitor is to be closest.
2. Internal Regulated Voltage Power Supply
REGFIL is a power supply of the analog circuit (typ. 2.3V). A 2.2F ±20% capacitor attached to the VSS1
pin eliminates the effects of high frequency noise. This capacitor should be placed as near as possible to
the AK4951A. No load current may be drawn from the REGFIL pin. All digital signals, especially clocks,
should be kept away from the REGFIL pin in order to avoid unwanted coupling into the AK4951A.
3. Reference Voltage
VCOM is a signal ground of this chip. A 2.2F ±20% capacitor attached to the VSS1 pin eliminates the
effects of high frequency noise. This capacitor should be placed as near as possible to the AK4951A. 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 AK4951A. Attention must be paid to the
printing pattern and the material of the capacitors to prevent superimposed noises and voltage drops
since the VCOM voltage is the reference of many functions.
4. Charge Pump
2.2μF±20% capacitors between the CP and CN pins, and the VEE and VSS2 pins should be low ESR
ceramic capacitors. These capacitors must be connected as close as possible to the pins. No load current
may be drawn from the VEE pin.
5. Analog Inputs
The microphone and line inputs support single-ended format. The input signal range scales with
nominally at typ. 2.07Vpp (@ 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/(2RC).
016001936-E-00
- 89 -
2016/03