AK4642EN Datasheet, PDF (50/83 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/HP/SPK-AMP

ASAHI KASEI
[AK4642EN]
<ALC Operation Example of Speaker Playback>
Register Name Comment
fs=44.1kHz
Data
Operation
LMTH
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
WTM1-0
*WTM1-0 bits should be the same data 11
23.2ms
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 43. ALC Operation Example of Speaker Playback
<Caution for using Piezo Speaker>
When a piezo speaker (load capacitance > 30pF) is used, resistances more than 10Ω should be inserted between SPP/SPN
pins and speaker in series, respectively, as shown in Figure 33. Zener diodes should be inserted between speaker and
GND as shown in Figure 33, in order to protect SPK-Amp of AK4642 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 33) ≤ 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 33. Speaker Output Circuit (Load Capacitance > 30pF)
MS0420-E-00
- 50 -
2005/09