AK5356 Datasheet, PDF (14/22 Pages) Asahi Kasei Microsystems – LOW POWER 20BIT ADC WITH MIC AMP & PGA

ASAHI KASEI
[AK5356]
n MIC Block
1. Pre-Amp
The Pre-Amp is non-inverting amplifier and internally biased to MVCM voltage with 100kΩ (typ.). Gain of the
Pre-Amp can select +13dB, +18dB, +28dB or +33dB by PREG1-0 bits.
Pre-Amp gain value of L/R channels change by zero crossing detection or timeout independently. Timeout cycle is fixed
to 2048/fs (=46.8ms @ fs = 44.1kHz). Zero crossing detection is done by IPGA block. When PMADC bit is “0”, gain of
Pre-Amp changes immediately.
An external capacitor is needed to cancel DC gain. The cut-off frequency is determined by an internal resistor (Ri) and
an external capacitor (C1).
C1
+
To MICL/MICR pins
Rf
Ri
PREL pin
PRER pin
-
+
Pre-Amp
Figure 9. Pre-Amp
2. Power Supply for MIC
The power supply for microphone device is supplied from MPWR pin. The output voltage is typically 2.16V(= 0.8 x
MVDD at MVDD=2.7V). MPWR pin can supply the current up to 1mA. When PMMIC bit is “0”, the output current is
not supplied.
MS0171-E-00
- 14 -
2002/08