ASAHI KASEI
[AK4370]
■ De-emphasis Filter
The AK4370 includes a digital de-emphasis filter (tc = 50/15μs), using an IIR filter corresponding to three sampling
frequencies (32kHz, 44.1kHz and 48kHz). The de-emphasis filter is enabled by setting DEM1-0 bits (Table 9).
DEM1 bit
DEM0 bit
De-emphasis
44.1kHz
OFF
0
0
1
1
0
1
0
1
Default
48kHz
32kHz
Table 9. De-emphasis Filter Frequency Select
■ Bass Boost Function
By controlling the BST1-0 bits, a low frequency boost signal can be output from DAC. The setting value is common for
both channels (Table 10).
BST1 bit
BST0 bit
BOOST
OFF
MIN
MID
MAX
0
0
1
1
0
1
0
1
Default
Table 10. Low Frequency Boost Select
■ Digital Mixing Function
MONO1-0 bits select the digital data mixing for the DAC (Table 11).
MONO1 bit
MONO0 bit
Lch
Rch
0
0
1
1
0
1
0
1
L
L
R
R
L
R
Default
(L+R)/2
(L+R)/2
Table 11. Mixer Setting
■ System Reset
PDN pin should be held to “L” upon power-up. The 4370 should be reset by bringing PDN pin “L” for 150ns or more. All
of the internal register values are initialized by the system reset. After exiting reset, VCOM, DAC, HPL, HPR, LOUT and
ROUT switch to the power-down state. The contents of the control register are maintained until the reset is completed.
The DAC exits reset and power down states by MCKI after the PMDAC bit is changed to “1”. The DAC is in power-down
mode until MCKI is input.
MS0595-E-00
2007/03
- 23 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
