AK4371 Datasheet, PDF (33/62 Pages) Asahi Kasei Microsystems – DAC with built-in PLL & HP-AMP

[AK4371]
< Analog Mixing Circuit for Headphone Output >
DALHL, LIN1HL, RIN1HL, LIN2HL, RIN2HL, LIN3HL and RIN3HL bits control each path switch of HPL output.
DARHR, LIN1HR, RIN1HR, LIN2HR, RIN2HR, LIN3HR and RIN3HR bits control each path switch of HPR output.
When L1HM=L2HM=L3HM bits = “0”, HPG1-0 bits = “00” (R_1H= R_2H= R_3H= R_DH= 100k) and ATTH4-0 bits =
“00H”(0dB), the mixing gain is +0.95dB(typ). When HPG1-0 bit = “01” (R_DH= 50k), the mixing gain of DAC path is
+6.95dB(typ). When HPG1-0 bit = “10” (R_DH= 25k), the mixing gain of DAC path is +12.95dB(typ). When L1HM,
L2HM and L3HM bits are “1”, LIN1/RIN1, LIN2/RIN2 and LIN3/RIN3 signals are output from HPL/R pins as (L+R)/2
respectively (R_1H= R_2H= R_3H= 200k).
When LDIF=LDIFH=LIN1L=RIN1R bits = “1”, LIN1 and RIN1 pins becomes IN− and IN+ pins, respectively. IN+ and
IN− pins can be used as full-differential mono line input for analog mixing for headphone-amp. In this case, LIN1HL,
RIN1HL, LIN1HR and RIN1HR bits should be “0”.
If the path is OFF and the signal is input to the input pin, the input pin should be biased to a voltage equivalent to VCOM
voltage (= 0.475 x AVDD) externally. Figure 46 shows the external bias circuit example.
Figure 27
LIN1 pin
RIN1 pin
LIN2 pin
RIN2 pin
LIN3 pin
RIN3 pin
DAC Lch
Figure 27
LIN1 pin
RIN1 pin
LIN2 pin
RIN2 pin
LIN3 pin
RIN3 pin
DAC Rch
100k(typ)
LDIFH bit
R1H
LIN1HL bit
R1H
RIN1HL bit
R2H
LIN2HL bit
R2H
RIN2HL bit
R3H
LIN3HL bit
R3H
RIN3HL bit
RDH
DALHL bit
100k(typ)
−
RH
+
100k(typ)
1.11RH
−
+
HP-Amp
LDIFH bit
R1H
LIN1HR bit
R1H
RIN1HR bit
R2H
LIN2HR bit
R2H
RIN2HR bit
R3H
LIN3HR bit
R3H
100k(typ)
RIN3HR bit
1.11RH
RDH
DARHR bit
−
RH
−
+
+
HP-Amp
Figure 25. Summation circuit for HPL/R output
HPL pin
HPR pin
MS0596-E-00
- 33 -
2007/04