LTC3588-1 Datasheet, PDF (12/20 Pages) Linear Technology – Piezoelectric Energy Harvesting Power Supply

LTC3588-1
APPLICATIONS INFORMATION
Introduction
The LTC3588-1 harvests ambient vibrational energy
through a piezoelectric element in its primary application.
Common piezoelectric elements are PZT (lead zirconate
titanate) ceramics, PVDF (polyvinylidene fluoride) poly-
mers, or other composites. Ceramic piezoelectric elements
exhibit a piezoelectric effect when the crystal structure
of the ceramic is compressed and internal dipole move-
ment produces a voltage. Polymer elements comprised
of long-chain molecules produce a voltage when flexed
as molecules repel each other. Ceramics are often used
under direct pressure while a polymer can be flexed more
readily. A wide range of piezoelectric elements are avail-
able and produce a variety of open-circuit voltages and
short-circuit currents. Typically the open-circuit voltage
and short-circuit currents increase with available vibrational
energy as shown in Figure 4. Piezoelectric elements can
be placed in series or in parallel to achieve desired open-
circuit voltages.
12
9
INCREASING
VIBRATION ENERGY
6
3
0
0
10
20
30
PIEZO CURRENT (μA)
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Figure 4. Typical Piezoelectric Load Lines
for Piezo Systems T220-A4-503X
The LTC3588-1 is well-suited to a piezoelectric energy
harvesting application. The 20V input protective shunt
can accommodate a variety of piezoelectric elements. The
low quiescent current of the LTC3588-1 enables efficient
energy accumulation from piezoelectric elements which
can have short-circuit currents on the order of tens of
microamps. Piezoelectric elements can be obtained from
manufacturers listed in Table 2.
Table 2. Piezoelectric Element Manufacturers
Advanced Cerametrics
www.advancedcerametrics.com
Piezo Systems
www.piezo.com
Measurement Specialties
www.meas-spec.com
PI (Physik Instrumente)
www.pi-usa.us
MIDE Technology Corporation
www.mide.com
Morgan Technical Ceramics
www.morganelectroceramics.com
The LTC3588-1 will gather energy and convert it to a use-
able output voltage to power microprocessors, wireless
sensors, and wireless transmission components. Such a
wireless sensor application may require much more peak
power than a piezoelectric element can produce. However,
the LTC3588-1 accumulates energy over a long period of
time to enable efficient use for short power bursts. For
continuous operation, these bursts must occur with a low
duty cycle such that the total output energy during the burst
does not exceed the average source power integrated over
an energy accumulation cycle. For piezoelectric inputs the
time between cycles could be minutes, hours, or longer
depending on the selected capacitor values and the nature
of the vibration source.
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