ELM412
Piezo Element Driver
Description
Features
The ELM412 is an 8 pin oscillator circuit for
• Low power CMOS design
driving piezo-electric elements. With the exception of
one external resistor, all of the circuitry required to
drive a typical piezo ‘bender’ is contained within this
chip.
• Wide supply range - 3.0 to 5.5 volt operation
• No external timing elements required
• Generates eight common piezo frequencies
• Bridged output for greater audio power
• Modified waveform for reduced harmonics
This circuit allows the user to select one of eight
possible operating frequencies by way of three logic
level inputs. These eight frequencies represent
some of the more common resonant frequencies
used for piezo elements. If desired, the frequency
can be continually varied by the controlling circuit.
The output of the ELM412 uses a bridge
configuration to obtain maximum audio drive for a
given power supply level. A single input pin is all that
is required to gate the output on and off.
Connection Diagram
PDIP and SOIC
(top view)
Typically the ELM412 is used to relieve
a
processor of the duty of waveform generation,
allowing it to concentrate on other activities,
although the circuit can also be used in stand-alone
tone generator circuits.
1
2
3
4
8
7
6
5
VDD
F2
F1
F0
VSS
Out1
Out2
Enable
Applications
• Computer controlled tone generation
• Alarm warning signals
• Keyboard click generation
• Logic probe circuits
Block Diagram
5
Enable
F2 F1 F0 Frequency
L
L
L
L
L
H
L
600
1200
2000
2400
2800
3200
3600
4000
7
6
Out1
Out2
Programmable
Oscillator
Waveform
Generator
L
H
H
L
L
H
L
H
H
H
H
2
3
4
F2
F1
F0
L
H
L
H
H
H
Table 1
ELM412DSB
Elm Electronics – Circuits for the Hobbyist
1 of 4
< http://www.elmelectronics.com/ >
ELM [ ELM ELECTRONICS ]
