AKD4635 datasheet(37/81 Pages) AKM

37 / 81 page

[AK4635]

Rev. 0.6

2007/10

- 37 -

■ System Reset

When power-up, the PDN pin should be “L” and change to “H” after all power are supplied. “L” time of 150ns or more

is needed to reset in the AK4635.

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

fs = 8kHz

fs = 16kHz

fs = 48kHz

1059/fs

132.4ms

66.2ms

22.1ms

291/fs

36.4ms

18.2ms

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

AK4635 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 AK4635 are reset by the PDN pin “L”. The device status can be

monitored by THDET bit.

■ MIC/LINE Input Selector

The AK4646 has an input selector. When MDIF bit is “0”, LIN bit selects MIC pin or LIN pin. When MDIF bit is “1”,

full-differential input is available.

MDIF bit

LIN bit

Input circuit

Input pin

Single-End

MIC pin

(default)

Single-End

LIN pin

Differential

MICP/MICN pin

Table 19. Input Select (x: Don’t care)

Figure 36 Input Selector

MIC/MICP pin

ADC

LIN/MICN pin

LIN bit

MDIF bit

AK4635

AKD4635 Datasheet(PDF) 37 Page - Asahi Kasei Microsystems

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