AK4641 Datasheet, PDF (48/51 Pages) Asahi Kasei Microsystems – 16 BIT CODEC WITH BLUETOOTH INTERFACE

ASAHI KASEI
[AK4641]
1. Grounding and Power Supply Decoupling
The AK4641 requires careful attention to power supply and grounding arrangements. AVDD, DVDD and BVDD are
usually supplied from the system’s analog supply. If AVDD, DVDD and BVDD are supplied separately, the power up
sequence is not critical. AVSS, DVSS and BVSS of the AK4641 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 AK4641 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 AVDD and VCOM pins in order to avoid unwanted coupling into
the AK4641.
3. Analog Inputs
The AK4641 has the 16bit Mono CODEC to connect with Bluetooth Module that supports 8kHz to 16kHz sample rate.
The AK4641 includes PLL that generate the master clock for Mono CODEC from input BSYNC signal. The PLL should
be powered-up after BSYNC signal is inputted. The PLL needs 90ms (max) lock time, when the PLL is powered-up
(PMBIF bit = “0” → “1”).
The Mic inputs are single-ended. AUX input is differential. The input signal range scales with nominally at 0.06 x AVDD
Vpp for the Mic input, 0.6 x AVDD Vpp for AUX 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 AK4641 can accept
input voltages from AVSS to AVDD.
4. Analog Outputs
The input data format for the DAC of both Stereo and Mono CODEC is 2’s complement. The output voltage is a positive
full scale for 7FFFH(@16bit) and a negative full scale for 8000H(@16bit). Mono output from the MOUT2 pin, Mono
Line Output from the MOUT+/MOUT− pins and Stereo Line Out from the LOUT/ROUT pins are centered at 0.45 x
AVDD.
MS0301-E-00
- 48 -
2004/05