AK4635 Datasheet, PDF (54/81 Pages) Asahi Kasei Microsystems – 16-Bit Mono CODEC with ALC & MIC/SPK/Video-AMP

[AK4635]
<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 48. Zener diodes should be connected between speaker and GND as shown in
Figure 48, in order to protect SPK-Amp of the AK4635 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 48) ≤ 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.
SPK-Amp
ZD
≥10Ω
SPP
SPN
≥10Ω
ZD
Figure 48. Circuit of Speaker Output (using a piezo speaker)
Rev. 0.6
- 54 -
2007/10