LTC3588-1 Datasheet, PDF (16/20 Pages) Linear Technology – Piezoelectric Energy Harvesting Power Supply

LTC3588-1
APPLICATIONS INFORMATION
DANGER! HIGH VOLTAGE!
150k 150k
120VAC
60Hz _{150k 150k}
1μF
6V
10μF
25V
4.7μF
6V
PZ1
PZ2
V_IN
PGOOD
LTC3588-1
CAP
SW
V_IN2
V_OUT
D1
D0
GND
PGOOD
10μH
V_OUT
3.6V
100μF
6V
35881 F09
DANGEROUS AND LETHAL POTENTIALS ARE PRESENT IN OFFLINE CIRCUITS!
BEFORE PROCEEDING ANY FURTHER, THE READER IS WARNED THAT
CAUTION MUST BE USED IN THE CONSTRUCTION, TESTING AND USE OF
OFFLINE CIRCUITS. EXTREME CAUTION MUST BE USED IN WORKING WITH
AND MAKING CONNECTIONS TO THESE CIRCUITS. REPEAT: OFFLINE
CIRCUITS CONTAIN DANGEROUS, AC LINE-CONNECTED HIGH VOLTAGE
POTENTIALS. USE CAUTION. ALL TESTING PERFORMED ON AN OFFLINE
CIRCUIT MUST BE DONE WITH AN ISOLATION TRANSFORMER CONNECTED
BETWEEN THE OFFLINE CIRCUIT’S INPUT AND THE AC LINE. USERS AND
CONSTRUCTORS OF OFFLINE CIRCUITS MUST OBSERVE THIS PRECAUTION
WHEN CONNECTING TEST EQUIPMENT TO THE CIRCUIT TO AVOID ELECTRIC
SHOCK. REPEAT: AN ISOLATION TRANSFORMER MUST BE CONNECTED
BETWEEN THE CIRCUIT INPUT AND THE AC LINE IF ANY TEST EQUIPMENT IS
TO BE CONNECTED.
Figure 9. AC Line Powered 3.6V Buck Regulator with
Large Output Capacitor to Support Heavy Loads
COPPER PANEL
(12" s 24")
PANELS ARE PLACED 6"
FROM 2' s 4' FLUORESCENT
LIGHT FIXTURES
COPPER PANEL
(12" s 24")
10μF
25V
1μF
6V
4.7μF
6V
PZ1
PZ2
V_IN
PGOOD
LTC3588-1
CAP
SW
V_IN2
V_OUT
D1
D0
GND
PGOOD
10μH
3.3V
10μF
6V
35881 F10
Figure 10. Electric Field Energy Harvester
Alternate Power Sources
The LTC3588-1 is not limited to use with piezoelectric ele-
ments but can accommodate a wide variety of input sources
depending on the type of ambient energy available. Figure 9
shows the LTC3588-1 internal bridge rectifier connected
to the AC line in series with four 150k current limiting
resistors. This is a high voltage application and minimum
spacing between the line, neutral, and any high voltage
components should be maintained per the applicable UL
specification. For general off-line applications refer to UL
regulation 1012.
Figure 10 shows an application where copper panels are
placed near a standard fluorescent room light to capacitively
harvest energy from the electric field around the light.
The frequency of the emission will be 120Hz for magnetic
ballasts but could be higher if the light uses electronic
ballast. The LTC3588-1 bridge rectifier can handle a wide
range of input frequencies.
The LTC3588-1 can also be configured for use with DC
sources such as a solar panel or thermal couple as shown
in Figures 11 and 12 by connecting them to one of the
PZ1/PZ2 inputs. Connecting the two sources in this way
prevents reverse current from flowing in each element.
Current limiting resistors should be used to protect the
PZ1 or PZ2 pins. This can be combined with a battery
backup connected to V_IN with a blocking diode.
35881f
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