AK4372 Datasheet, PDF (31/62 Pages) Asahi Kasei Microsystems – DAC with built-in PLL & HP-AMP

[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” (R_1H= R_2H = 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 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.
Figure 27
LIN pin
RIN pin
MIN pin
DAC Lch
Figure 27
LIN pin
RIN pin
MIN pin
DAC Rch
100k(typ)
LDIFH bit
R1H
LINHL bit
R1H
RINHL bit
R2H
MINHL bit
RDH
DALHL bit
100k(typ)
−
RH
+
1.11RH
−
+
HP-Amp
100k(typ)
LDIFH bit
R1H
LINHR bit
R1H
RINHR bit
R2H
100k(typ)
MINHR bit
RDH
DARHR bit
1.11RH
−
RH
−
+
+
HP-Amp
Figure 25. Summation circuit for HPL/R output
HPL pin
HPR pin
MS0684-E-02
- 31 -
2008/12