AK4691EG AKM [Asahi Kasei Microsystems], AK4691EG Datasheet - Page 30

• Manufacturer Part Number: AK4691EG
• Description: 4ch ADC + 2ch DAC with MIC/HP/SPK-AMP
• Manufacturer: AKM [Asahi Kasei Microsystems]

■
1. Pre- Amp
Note 49. Input signal is bypassed to Pre-Amp and is inputted to MIX-Amp. The cut-off frequency is determined by input
MS0672-E-00
Pre-Amp includes a selector, Internal MIC or External MIC Mode can be selected by PRSL2-1 and PRSR2-1 bits. The
Pre-Amp is non-inverting amplifier and internally biased to VCOM voltage with 100kΩ (typ.). The gain from Pre-Amp
#1 to MIXL/R-Amp is set by PRG12-10, and the gain from Pre-Amp #2 to MIXL/R-Amp is set by PRG22-20 bits
(Table
An external capacitor (C1) is needed to cancel DC gain. The cut-off frequency is determined by an external capacitor
(C1) and internal feedback resistor (Rn). The internal feedback resistor (Rn) depends on Pre-Amp Gain and is typ ±
30%.
MIC BLOCK
impedance (typ. 100kΩ) and external capacitors (C2, C3).
15).
PRG12 bit
PRG22 bit
Table 15. Relationship between Pre-Amp Gain and Feedback resistor (N/A: Not available)
0
0
0
0
1
1
1
1
PRSL1 bit
PRSL2 bit
INT pin
EXT pin
0
1
0
1
PRG11 bit
PRG21 bit
0
0
1
1
0
0
1
1
C2
C3
+
+
Input Signal Source
Input Signal Source
Lch Pre-Amp #1
Lch Pre-Amp #2
Table 14. Pre-Amp Input Signal Source Select
EXTL1 pin
EXTL2 pin
INTL1 pin
INTL2 pin
PRSx bit
PRG10 bit
PRG20 bit
0
1
0
1
0
1
0
1
Figure 21. Pre-Amp
- 30 -
-4.4dB (Note 49)
+24dB (default)
To MIX-Amp (@ PRG12-10/PRG22-20 bits = “000”)
FB bit = “0”
-
+
C1
+18dB
+20dB
+28dB
PRSR1 bit
PRSR2 bit
Pre-Amp
+
0
1
0
1
Gain
Rn
To MIX-Amp
0dB (Note 49)
FB bit = “1”
Input Signal Source
Input Signal Source
Rch Pre-Amp #1
Rch Pre-Amp #2
+22.4dB
+24.4dB
+28.4dB
+32.4dB
N/A
EXTR1 pin
EXTR2 pin
INTR1 pin
INTR2 pin
Rn(typ)
4.4 kΩ
3.5kΩ
3.5kΩ
2.2kΩ
1.4kΩ
[AK4691]
2007/11