AK4645EN Datasheet, PDF (44/96 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/HP-AMP

ASAHI KASEI
[AK4645]
2. ALCϦΧόϦಈ࡞
ALCϦΧόϦಈ࡞͸ɺWTM2-0Ͱઃఆ͞Εͨ࣌ؒ(Table 31)଴ػΛߦ͍ɺ͜ͷؒɺग़ྗ৴߸͕ALCϦΧόϦ଴
ػΧ΢ϯλϦηοτϨϕϧ(Table 28)Λӽ͢͜ͱ͕ͳ͚Ε͹ALCϦΧόϦಈ࡞Λߦ͍·͢ɻ͜ͷALCϦΧόϦ
ಈ࡞͸ઃఆ͞Εͨج४Ϩϕϧ(Table 33) ·ͰZTM1-0 bitsͰઃఆͨ࣌ؒ͠(Table 30)ͰθϩΫϩεݕग़ಈ࡞Λߦ
͍ͳ͕ΒɺRGAIN1-0 bitsͰઃఆͨ͠஋(Table 32)͚ͩIVL, IVR஋(L/Rڞ௨)Λࣗಈతʹ૿Ճͤ͞·͢ɻ͜ͷALC
ϦΧόϦಈ࡞͸WTM2-0 bitsͰઃఆͨ͠पߦͰظΘΕ·͢ɻͨͩ͠ɺWTM2-0 bitsͰͷઃఆΑΓZTM1-0 bits
Ͱͷઃఆ͕௕͍৔߹ʹ͓͍ͯɺ৴߸͕θϩΫϩε͠ͳ͍ͱ͖ʹ͸ɺZTM1-0 bitsͷઃఆͰALCϦΧόϦಈ࡞͕
ߦΘΕ·͢ɻ
ྫ͑͹ɺࡏݱͷIVL, IVR஋͕30Hͷ৔߹ɺRGAIN1-0 bits = “01”(2 steps)ʹઃఆ͓ͯ͘͠ͱɺALCϦΧόϦಈ࡞
ʹΑͬͯIVL, IVR஋͸32Hʹมߋ͞Εɺ0.75dB(0.375dB x 2)૿Ճ͞Ε·͢ɻIVL, IVR஋͕ج४Ϩϕϧ (REF7-0
bits)ʹୡͨ͠৔߹ɺIVL, IVR஋ͷ૿Ճ͸ߦ͍·ͤΜɻ
·ͨɺALCϦΧόϦ଴ػதʹ
(ϦΧόϦ଴ػΧ΢ϯλϦηοτϨϕϧ) ≤ Output Signal < (Ϧϛολݕग़Ϩϕϧ)
ͱͳ͍ͬͯΔ৔߹ɺ଴ػλΠϚ͸Ϧηοτ͞Ε·͢ɻͦͷͨΊɺ
(ϦΧόϦ଴ػΧ΢ϯλϦηοτϨϕϧ) > Output Signal
ͱͳ͔ͬͨ࣌Βɺ଴ؒ࣌ػͷΧ΢ϯτ͕։࢝͞Ε·͢ɻ
·ͨɺALCಈ࡞͸ΠϯύϧεੑͷϊΠζʹ΋ରԠͨ͠ALCʹͳ͍ͬͯ·͢ɻΠϯύϧεੑͷϊΠζ͕ೖྗ͞
Εͨ৔߹ɺ௨ৗͷϦΧόϦಈ࡞ΑΓ΋ૣ͍αΠΫϧͰϦΧόϦಈ࡞(ϑΝʔετϦΧόϦಈ࡞)Λߦ͍·͢ɻ
ྫ͑͹ɺϚΠΫϩϑΥϯʹॠؒతʹେ͖ͳԻ͕ೖྗ͞Εͨ৔߹ɺ͜ͷಈ࡞ʹΑΓେ͖ͳԻʹຒ΋Εͨখ৴߸
Λվળ͢Δ͜ͱ͕Ͱ͖·͢ɻϑΝʔετϦΧόϦಈ࡞ͷ଎͞͸ɺRFST1-0 bits ʹΑΓઃఆ͠·͢(Table 34)ɻ
WTM2
0
0
0
0
1
1
1
1
WTM1
0
0
1
1
0
0
1
1
WTM0
ALCϦΧόϦपظ
8kHz
16kHz
44.1kHz
0
128/fs
16ms
8ms
2.9ms
1
256/fs
32ms
16ms
5.8ms
0
512/fs
64ms
32ms
11.6ms
1
1024/fs
128ms
64ms
23.2ms
0
2048/fs
256ms
128ms
46.4ms
1
4096/fs
512ms
256ms
92.9ms
0
8192/fs
1024ms
512ms
185.8ms
1
16384/fs
2048ms
1024ms
371.5ms
Table 31. ALCϦΧόϦ଴ؒ࣌ػͷઃఆ
Default
RGAIN1 RGAIN0
GAIN STEP
0
0
1 step
0.375dB
0
1
2 step
0.750dB
1
0
3 step
1.125dB
1
1
4 step
1.500dB
Table 32. ALC ϦΧόϦήΠϯྔͷઃఆ
Default
MS0543-J-00
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2006/09