ak4642e AKM Semiconductor, Inc., ak4642e Datasheet - Page 50

• Manufacturer Part Number: ak4642e
• Description: Stereo Codec With Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
<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.
MS0420-E-00
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
Register Name
LMTH
ZELMN
ZTM1-0
WTM1-0
REF7-0
IVL7-0,
IVR7-0
LMAT1-0
RGAIN1-0
ALC
For example, zener diode which zener voltage is 5.1V(Min: 4.97V, Max: 5.24V) can be used.
Figure 33. Speaker Output Circuit (Load Capacitance > 30pF)
SPK-Amp
Table 43. ALC Operation Example of Speaker Playback
Comment
Limiter detection Level
Limiter zero crossing detection
Zero crossing timeout period
Recovery waiting period
*WTM1-0 bits should be the same data
Maximum gain at recovery operation
Gain of IVOL
Limiter ATT step
Recovery GAIN step
ALC enable
as ZTM1-0 bits
SPP
SPN
- 50 -
≥10Ω
≥10Ω
ZD
ZD
Data
C1H
91H
11
00
00
10
00
0
1
fs=44.1kHz
−2.5dBFS
Operation
23.2ms
11.6ms
Enable
+18dB
Enable
1 step
1 step
0dB
[AK4642EN]
2005/09