Datasheet

LTC3588-1
14
35881fa
APPLICATIONS INFORMATION
Figure 8. Piezo Energy Harvester with Battery Backup
Additional Applications with Piezo Inputs
The versatile LTC3588-1 can be used in a variety of con-
fi gurations. 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 fi rst.
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 confi guration 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 standalone nanopower buck converter. In this case the
bridge is unused and the blocking diode is unnecessary.
35881 F08
PZ1
V
IN
CAP
V
IN2
D1
D0
PZ2
PGOOD
SW
V
OUT
PZ1
PZ2
LTC3588-1
PIEZO SYSTEMS T220-A4-503X
IR05H40CSPTR
GND
47µF
6V
10µH
V
OUT
3.3V
PGOOD
100µF
16V
9V
BATTERY
1µF
6V
4.7µF
6V
Figure 7. Dual Rail Power Supply with Single Piezo and
Automatic Supply Sequencing
35881 F07
PZ1
V
IN
CAP
V
IN2
D1
D0
PZ2
PGOOD
SW
V
OUT
LTC3588-1
GND
10µF
6V
10µF
6V
10µH10µH
1.8V
3.6V
PGOOD2PGOOD1
1µF
6V
PZ2
V
IN
CAP
V
IN2
D1
D0
PZ1
PGOOD
SW
V
OUT
LTC3588-1
GND
4.7µF
6V
1µF
6V
4.7µF
6V
10µF
25V
10µF
25V
MIDE V25W