LTC3588-1 Datasheet, PDF (15/20 Pages) Linear Technology – Piezoelectric Energy Harvesting Power Supply

LTC3588-1
APPLICATIONS INFORMATION
Additional Applications with Piezo Inputs
The versatile LTC3588-1 can be used in a variety of con-
figurations. Figure 7 shows a single piezo source powering
two LTC3588-1s simultaneously, providing capability for
multiple rail systems. This setup features automatic sup-
ply sequencing as the LTC3588-1 with the lower voltage
output (i.e. lower UVLO rising threshold) will come up first.
As the piezo provides input power both V_IN rails will
initially come up together, but when one output starts
drawing power, only its corresponding V_IN will fall as the
bridges of each LTC3588-1 provide isolation. Input piezo
energy will then be directed to this lower voltage capacitor
until both V_IN rails are again equal. This configuration is
expandable to any number of LTC3588-1s powered by a
single piezo as long as the piezo can support the sum total
of the quiescent currents from each LTC3588-1.
A piezo powered LTC3588-1 can also be used in concert
with a battery connected to V_IN to supplement the system
if ambient vibrational energy ceases as shown in Figure 8.
A blocking diode placed in series with the battery to V_IN
prevents reverse current in the battery if the piezo source
charges V_IN past the battery voltage. A 9V battery is shown,
but any stack of batteries of a given chemistry can be used
as long as the battery stack voltage does not exceed 18V.
In this setup the presence of the piezo energy harvester
can greatly increase the life of the battery. If the piezo
source is removed the LTC3588-1 can serve as a stand-
alone nanopower buck converter. In this case the bridge
is unused and the blocking diode is unnecessary.
PIEZO SYSTEMS T220-A4-503X
PZ1
PZ2
PGOOD1 PGOOD
V_IN
10μH
LTC3588-1
3.6V
SW
CAP
10μF
6V
V_OUT
V_IN2
D1
GND
D0
1μF
6V
10μF
25V
4.7μF
6V
1μF
6V
10μF
25V
4.7μF
6V
PZ1
PZ2
V_IN
PGOOD
LTC3588-1
CAP
SW
V_IN2
V_OUT
D1
D0
GND
PGOOD2
10μH
1.8V
10μF
6V
35881 F07
Figure 7. Dual Rail Power Supply with Single Piezo and
Automatic Supply Sequencing
PIEZO SYSTEMS T220-A4-503X
IR05H40CSPTR
9V
BATTERY
100μF
16V
1μF
6V
4.7μF
6V
PZ1
PZ2
V_IN
PGOOD
LTC3588-1
CAP
SW
V_IN2
V_OUT
D1
PZ1
D0
PZ2
GND
PGOOD
10μH
V_OUT
3.3V
47μF
6V
35881 F08
Figure 8. Piezo Energy Harvester with Battery Backup
35881f
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