AK4560A Datasheet, PDF (29/47 Pages) Asahi Kasei Microsystems – 16bit CODEC with ALC and MIC/HP/SPK-Amps

ASAHI KASEI
[AK4560A]
1. Pre- Amp
Pre-Amp is non-inverting amplifier and internally biased to MVCM voltage with 100kΩ (typ.). Gain value of Pre-Amp is
adjusted by external resistor.
Gain (1+Rf/Ri) of Pre-Amp should use a range of +18∼30dB.
An external capacitor needs to cancel DC gain. Cut-off frequency is decided by a external input resistor (Ri) and a
capacitor (C).
C Ri
Rf
62
63
INT_MIC_L
60
EXT_MIC_L
59
-
+
Pre Amp
Figure 14. Pre-Amp
2. EQ-Amp
EQ-Amp is block to emphasize a stereo feeling at using Internal MIC Mode.
EQ-Amp can be emphasized by adding the output signal from pre-amplifier and the reverse channel differentially. When
External MIC Mode is selected, EQ-Amp does not connect.
3. HPF-Amp
To cancel wind-noise, AK4560A has the HPF-Amp which is non-inverting amplifier, 2^nd order high pass filter and gain of
0dB. The HPF-Amp can be ON/OFF by controlling the internal registers. In case of OFF, HPF-Amp becomes a unity gain
buffer. This HPF-Amp can use when Internal MIC Mode is selected. In case of External MIC Mode, the control of
HPF-Amp is invalid and becomes a unity gain buffer.
4. Power Supply for MIC
Power Supply for microphone is supplied from MPWR pin. Output voltage is MVDD – 1.4V (typ) . For example, MPWR
pin outputs 2.5V at MVDD = 3.9V. And MPWR pin can supply the current until 3mA.
When MIC bit is “0”, the power supply current can be stopped.
MS0028-E-00
- 29 -
2000/05