AK4643 Datasheet, PDF (65/104 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/HP/RCV/SPK-AMP

ASAHI KASEI
[AK4643]
<ALC Operation Example of Speaker Playback>
Register Name Comment
fs=44.1kHz
Data
Operation
LMTH1-0
Limiter detection Level
00
−2.5dBFS
ZELMN
Limiter zero crossing detection
0
Enable
ZTM1-0
Zero crossing timeout period
10
11.6ms
Recovery waiting period
WTM2-0
*WTM2-0 bits should be the same or 11
23.2ms
longer data as ZTM1-0 bits
REF7-0
Maximum gain at recovery operation C1H
+18dB
IVL7-0,
IVR7-0
Gain of IVOL
91H
0dB
LMAT1-0
Limiter ATT step
00
1 step
RGAIN1-0
Recovery GAIN step
00
1 step
ALC
ALC enable
1
Enable
Table 59. ALC Operation Example of Speaker Playback
<Caution for using Piezo Speaker>
When a piezo speaker is used, resistances more than 10Ω should be inserted between SPP/SPN pins and speaker in series,
respectively, as shown in Figure 61. Zener diodes should be inserted between speaker and GND as shown in Figure 61, in
order to protect SPK-Amp of AK4643 from the power that the piezo speaker outputs when the speaker is pressured. Zener
diodes of the following zener voltage should be used.
0.92 x HVDD ≤ Zener voltage of zener diodo (ZD in Figure 61) ≤ HVDD+0.3V
Ex) In case of HVDD = 5.0V: 4.6V ≤ ZD ≤ 5.3V
For example, zener diode which zener voltage is 5.1V(Min: 4.97V, Max: 5.24V) can be used.
SPK-Amp
ZD
≥10Ω
SPP
SPN
≥10Ω
ZD
Figure 61. Speaker Output Circuit (Load Capacitance > 30pF)
MS0476-E-01
- 65 -
2006/10