[AK4634]
<Caution for using Piezo Speaker>
When a piezo speaker is used, resistances more than 10Ω should be connected between the SPP/SPN pins and speaker in
series, respectively, as shown in Figure 44. Zener diodes should be connected between speaker and GND as shown in
Figure 44, in order to protect SPK-Amp of the AK4634 from the power that is the piezo speaker output when the speaker
is pressured. Zener diodes of the following Zener voltage should be used.
92% of SVDD ≤ Zener voltage of Zener diodo (ZD of Figure 44) ≤ SVDD+0.3V
Ex) In case of SVDD = 3.8V :3.5V ≤ ZD ≤ 4.1V
For example, Zener diode which Zener voltage is 3.9V(Min 3.7V, Max 4.1V) can be used.
ZD
SPK-Amp
≥10Ω
SPP
SPN
≥10Ω
ZD
Figure 44. Circuit of Speaker Output (using a piezo speaker)
Rev. 0.5
2007/10
- 52 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
