[AK4372]
< Analog Mixing Circuit for Headphone Output >
DALHL, LINHL, RINHL and MINHL bits control each path switch of the HPL output. DARHR, LINHR, RINHR and
MINHR bits control each path switch of the HPR output.
When LHM bit = “0”, HPG1-0 bits = “00” (R1H= R2H = RDH= 100k) and ATTH4-0 bits = “00H”(0dB), the mixing gain is
+0.95dB(typ). When HPG1-0 bit = “01” (RDH= 50k), the mixing gain of DAC path is +6.95dB(typ). When HPG1-0 bit =
“10” (RDH= 25k), the mixing gain of DAC path is +12.95dB(typ). When LHM bit is “1”, LIN and RIN signals are output
from the HPL/R pins as (L+R)/2 respectively.
When LDIF=LDIFH=LINL=RINR bits = “1”, the LIN and RIN pins becomes IN+ and IN− pins, respectively. The IN+
and IN− pins can be used as full-differential mono line input for analog mixing for headphone-amp. In this case, LINHL,
RINHL, LINHR and RINHR 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 51 shows the external bias circuit example.
100k(typ)
Figure 27
LDIFH bit
R1H
LIN pin
LINHL bit
R1H
RIN pin
RINHL bit
R2H
100k(typ)
MIN pin
1.11RH
MINHL bit
DALHL bit
RDH
RH
DAC Lch
−
+
−
+
HPL pin
HP-Amp
100k(typ)
R1H
Figure 27
LDIFH bit
LIN pin
RIN pin
MIN pin
LINHR bit
RINHR bit
MINHR bit
DARHR bit
R1H
R2H
100k(typ)
1.11RH
RDH
RH
DAC Rch
−
+
−
+
HPR pin
HP-Amp
Figure 25. Summation circuit for HPL/R output
MS0684-E-02
2008/12
- 31 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
