ak4651 AKM Semiconductor, Inc., ak4651 Datasheet - Page 61

• Manufacturer Part Number: ak4651
• Description: 16bit ?? Codec With Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
MS0503-E-00
Volume Control (68H)
ROTM: ALC2 Recovery Waiting Period (Table 39)
LMTH: ALC1 Limiter Detection Level / Recovery Waiting Counter Reset Level (Table 15)
RGAIN: ALC1 Recovery GAIN Step (Table 20)
LMAT1-0: ALC1 Limiter ATT Step (Table 16)
ZELMN: Zero crossing detection enable at ALC1 Limiter operation
ALC1: ALC1 enable
ALC2: ALC2 enable
ATTS2-0: Volume control of signal from IPGA to Headphone/Speaker-Amp (Table 7)
ATTM: Volume control of signal from IPGA to Mono Line Output (Table 8)
ATS: Digital attenuator transition time setting (Table 26)
0: 2048/fs (Default)
1: 512/fs
Default: “0” (−6dB/−8dB)
Default: “0” (0.5dB)
Default: “00” (0.5dB)
0: Enable (Default)
1: Disable
0: ALC1 Disable (Default)
1: ALC1 Enable
0: ALC2 Disable (Default)
1: ALC2 Enable
Default: “2H” (−12dB)
0: 0dB (Default)
1: −4dB
Default: “0” (531/fs)
The ALC1 limiter detection level and the ALC1 recovery counter reset level may be offset by about ±2dB.
During the ALC1 recovery operation, RGAIN bit sets the number of steps changed from the current IPGA
value. For example, when the current IPGA value is “30H” and RGAIN bit is “1”, the IPGA changes to “32H”
by the ALC1 recovery operation and the output signal level is gained up by 1dB (=0.5dB x 2). When the IPGA
value exceeds the maximum level (REF6-0 bits), the IPGA value does not increase.
During the ALC1 limiter operation, when IPGA value exceeds the ALC1 limiter detection level set by LMTH
bit, LMAT1-0 bits set the number of steps attenuated from the current IPGA value. For example, when the
current IPGA value is “47H” and LMAT1-0 bits is “11”, the IPGA value decreases to “43H” when the ALC1
limiter operation starts, resulting in the input signal level being attenuated by 2dB (=0.5dB x 4). When the
attenuation value exceeds IPGA = “00” (−8dB), it clips to “00”.
When the ZELMN bit = “0”, the IPGA performs a zero crossing or timeout and the IPGA value is changed by
the ALC1 operation. The zero crossing timeout is the same as the ALC1 recovery operation. When the
ZELMN bit = “1”, the IPGA value is changed immediately.
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[AK4651]
2006/04