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AK4565

Low Power 20bit CODEC with built-in ALC

Asahi Kasei Microdevices 

ASAHI KASEI

[AK4565]

n FADEOUT Mode

In FADEOUT mode, the present IPGA value decreases gradually down to the MUTE state when FDOUT bit changes from

“0” to “1”. This operation is done by the zero crossing detection. If the large signal is supplied to the ALC circuit during the

FADEOUT operation, the ALC limiter operation starts. However, the total time of the FADEOUT operation is the same

time, even if the limiter operation is done. The period of FADEOUT is set by FDTM1-0 bits, the number of step is set by

FDATT bit. When FDOUT bit changes into “0” during the FADEOUT operation, the ALC operation start from the preset

IPGA value. When FDOUT and ALC bits change into “0” at the same time, the FADEOUT operation stops and the IPGA

kept the value at that time.

NOTE: When FDIN and FDOUT bits are set to “1” at the same time, FADEOUT operation is prior to FADEIN operation.

IPGA Output

ALC bit

FDOUT bit

(2)

(1)

(3)

(4) (5) (6) (7) (8)

Figure 15. Example for controlling sequence in FADEOUT operation

(1) WR (FDOUT = “1”): The FADEOUT operation starts. Then ALC bit should be always “1”.

(2) FADEOUT time is set by FDTM1-0 and FDATT bits.

During the FADEIN operation, the zero crossing timeout period is ignored and becomes the same as the FADEIN

period.

E.g. FDTM1-0 = 32ms, FDATT = 1step

(96 x FDTM1-0) / FDATT = 96 x 32ms / 1 = 3.07s

(3) The FADEOUT operation is completed. The IPGA value is the MUTE state. If FDOUT bit keeps “1”, the IPGA value

keeps the MUTE state.

(4) Analog and digital outputs mutes externally. Then the IPGA value is the MUTE state.

(5) WR (ALC = FDOUT = “0”): Exit the ALC and FADEOUT operations

(6) WR (IPGA): The IPGA value changes the initial value (exiting MUTE state).

(7) WR (ALC = “1”, FDOUT = “0”): The ALC operation restarts. But the ALC bit should be written until completing zero

crossing detection operation of IPGA.

(8) Release an external mute function for analog and digital outputs.

MS0132-E-01

- 18 -

2003/05

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