In contrast to an electromagnetic buzzer which is driven by a current flowing through a built-in electromagnet coil, a piezoelectric sound component is driven by a voltage applied to piezoelectric ceramic. Consequently, it features much lower current consumption than that of an electromagnetic buzzer.
The current consumption (excluding that of the peripheral circuit) by a piezoelectric sounder (external drive type) can be calculated simply from the theoretical equation below.
Average value of current (theoretical value)When the charging and discharging times of a piezoelectric sounder (external drive type) are significantly smaller than the length of one period of the input signal, the average value of the current which flows into the piezoelectric sounder (external drive type) during a half period can be calculated from the following equation.
 | Q: Charge accumulated in the piezoelectric sounder
T: Length of one period of the drive signal (=1/f)
C: Electrostatic capacitance of the piezoelectric sounder
V: Drive voltage
f: Frequency of the drive signal
|
Calculated value of current consumption for each part numberThe average value of the current flowing through the piezoelectric sounder (external excited type), calculated using the above equation for each part No., is shown in the table below.
Part No.
| Current consumption [mA] | Drive frequency
[kHz]
| Electrostatic capacitance
[nF]
|
Drive voltage (square wave)
|
3 Vo-p
| 5 Vo-p
| 12 Vo-p
|
| PKMCS1818E2001-R1 | 0.4 | 0.7 | 1.7 | 2 | 35 |
| PKMCS1818E20A0-R1 | 0.4 | 0.7 | 1.7 | 2 | 35 |
| PKMCS0909E4000-R1 | 0.3 | 0.4 | 0.9 | 4 | 9 |
| PKLCS1212E4001-R1 | 0.5 | 0.8 | 1.9 | 4 | 19.5 |
| PKLCS1212E40A1-R1 | 0.5 | 0.8 | 1.9 | 4 | 19.5 |
| PKLCS1212E2000-R1 | 0.3 | 0.6 | 1.3 | 2 | 28 |
| PKLCS1212E20A0-R1 | 0.3 | 0.6 | 1.3 | 2 | 28 |
| PKLCS1212E2400-R1 | 0.4 | 0.7 | 1.6 | 2.4 | 28 |
| PKLCS1212E24A0-R1 | 0.4 | 0.7 | 1.6 | 2.4 | 28 |
| PKHPS0013E4000-A2 | 0.1 | 0.2 | 0.5 | 4 | 5.5 |
| PKM17EPP-2002-B0 | 0.4 | 0.7 | 1.6 | 2 | 34 |
| PKM22EPPH2001-B0 | 0.2 | 0.4 | 0.9 | 2 | 19 |
| PKM22EPPH2002-B0 | 0.2 | 0.4 | 0.9 | 2 | 19 |
| PKM22EPPH4001-B0 | 0.3 | 0.5 | 1.2 | 4 | 12 |
| PKM22EPPH4002-B0 | 0.3 | 0.5 | 1.2 | 4 | 12 |
| PKM22EPPH4005-B0 | 0.3 | 0.5 | 1.2 | 4 | 12 |
| PKM22EPPH4007-B0 | 0.3 | 0.5 | 1.2 | 4 | 12 |
| PKM22EPPH4012-B0 | 0.3 | 0.5 | 1.2 | 4 | 12 |
| PKM34EWH1101C | 0.3 | 0.4 | 1.1 | 1.1 | 40 |
| PKM34EWH1201C | 0.2 | 0.4 | 0.9 | 1.2 | 32 |
| PKM44EWH1001C | 0.4 | 0.7 | 1.6 | 1 | 68 |
Note: The electrostatic capacitance is the center value, the tolerance is ±30%, and PKMCS & PKLCS is a reference value.