[AK4634]
■ System Reset
When power-up, the PDN pin should be “L” and change to “H” after all powers are supplied. “L” time of 150ns or more
is needed to reset the AK4634.
The ADC enters an initialization cycle when the PMADC bit is changed from “0” to “1”. The initialization cycle time is
1059/fs, or 133ms@fs = 8kHz. During the initialization cycle, the ADC digital data outputs of both channels are forced to
a 2's compliment, “0”. The ADC output reflects the analog input signal after the initialization cycle is complete. The DAC
does not require an initialization cycle.
(Note) Off-set occurs in the initial data depending on the conditions of a microphone and cut-off frequency of HPF.
When Off-set becomes a problem, lengthen initialization time of ADC as ADRST bit = “0” or do not use initial
output data of ADC.
Init Cycle
ADRST bit
Cycle
1059/fs
291/fs
fs = 8kHz
132.4ms
36.4ms
fs = 16kHz
66.2ms
18.2ms
fs = 48kHz
22.1ms
0
1
6.1ms
Table 18 Initialization cycle of ADC
■ Thermal Shut Down
When the internal device temperature rises up irregularly (e.g. output pins of speaker amplifier are shortened), the
AK4634 is powered down automatically and then THDET bit becomes “1”. The powered-down speaker amplifier do not
return to normal operation unless SPK-Amp blocks of the AK4634 are reset by the PDN pin “L”. The device status can be
monitored by THDET bit.
■ MIC/LINE Input Selector
The AK4634 has an input selector. When MDIF bit is “0”, LIN bit selects the MIC pin or LIN pin. When MDIF bit is “1”,
full-differential input is available.
MDIF bit
LIN bit
Input circuit
Single-End
Single-End
Differential
Input pin
MIC pin
LIN pin
0
0
1
0
1
x
(default)
MICP/MICN pin
Table 19. Input Select (x: Don’t care)
AK4634
LIN bit
MIC/MICP pin
ADC
LIN/MICN pin
MDIF bit
Figure 32 Input Selector
MS0983-E-00
2008/07
- 35 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
