ELM412
Output Waveforms
The output waveforms are generated as long as
the enable input remains high. When brought low,
the current cycle completes before the output
ceases.
Enable
Out1
Out2
Out1 - Out2
Figure 2.
Example Application
Operation of the ELM412 is straightforward,
requiring little explanation. Typically the resonant
frequency of the piezo element is determined, and
pins 2, 3 and 4 are connected for this frequency. In
the circuit of Figure 3, the frequency has been set for
2400Hz. A single bit from a control circuit is then
used to turn the buzzer on and off.
0.01µF
+5V
The 2.2KW resistor shown in the circuit serves
two purposes. One is to provide a current limit for the
ELM412 as it tries to rapidly change the piezo
voltage (the piezo is like a large capacitor), and the
other is to simply limit the output loudness.
1
2
3
4
8
7
6
5
Piezo
Element
The only other detail in Figure 3 is the customary
0.01µF capacitor for supply decoupling. It’s always
good practice to add one, although it’s often not
essential.
2.2KW
Control Bit from the
Microprocessor
(1=on, 0=off)
Figure 3.
4 of 4
ELM412DSB
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