AK4545 Datasheet, PDF (30/33 Pages) Asahi Kasei Microsystems – AC97 AUDIO CODEC WITH SRC AND DIT

[ASAHI KASEI]
[AK4545]
1. Grounding and Power Supply Decoupling
AVdd1 and AVdd2 should be connected and derived from same AVdd. And DVdd1 and DVdd2 also should be
connected and derived from same DVdd. 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
AK4545 as possible, with the small value ceramic capacitor being the nearest.
No specific power supply sequencing is required on the AK4545.
2. On-chip Voltage Reference
The on-chip voltage reference are output on the VRAD ,VRDA and Vref pins for decoupling. A electrolytic capacitor
less than 10uF in parallel with a 0.1 uF ceramic capacitor attached to these pins eliminates the effects of high
frequency noise. No load current may be drawn from VRAD , VRDA, and Vref pins. All signals, especially clocks,
should be kept away from the VRAD , VRDA and Vref pins in order to avoid unwanted coupling into delta-sigma
modulators.
3.Analog input
Since many analog levels can be as high as 2Vrms, the circuit shown below can be used to attenuate the analog input
2Vrms to 1Vrms which is the maximum voltage allowed for all the stereo line-level inputs.
J15
LINE_IN_L
J4
LINE_IN_R
4.PC_BEEP
If PC_BEEP isn’t used, this input pin should be NC(open) or connected to Analog-Ground through capacitor. In this
case, the register for PC-Beep(04h,D15) should be set to mute on ”1”. (Note that the default of PC_BEEP is mute off.)
In addition, when PC_BEEP is connected through capacity to Analog-Ground, PC_BEEP is recommended to be
separated from other non-used input pins.
5.Microphone Input design
VrefOut of AK4545 28pin can be used for Bias of Microphone Input.
MS0058-E-00
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2000/11