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DEMO MANUAL DC2048A
connection to a Dust mote (Dc9003a-B)
Figure 12 shows the LTC3330 with an output superca-
pacitor, a Dust mote attached, a battery installed and EH_ON
connected to OUT2. In this configuration, when EH_ON
is low, V
will be set to 2.5V and when EH_ON is high,
OUT
V
will be set to 3.6V. The first marker in Figure 13 is
OUT
where the vibration source was activated; V
above the VIN_UVLO_RISING threshold. EH_ON will then
go high causing V
to rise towards 3.6V (V
OUT
at 2.5V because the battery had charged it up initially).
At the same time EH_ON goes high, PGVOUT will go low,
since the new V
level of 3.6V has not been reached.
OUT
As the charge on V
is being transferred to V
IN
discharging and when V
threshold, EH_ON will go low, causing the targeted V
to again be 2.5V. Given that the output capacitor is very
large and the average load is less than the input power
supplied by the Mide piezoelectric transducer, the output
voltage will increase to the higher set-point of 3.6V over
many cycles. During the transition from the BAT set-point
22µF
25V
4.7µF , 6V
+
22µF
CR2032
6V
10
then rises
IN
started
OUT
, V
OUT
reaches its UVLO_FALLING
IN
PIEZO
MIDE V25W
AC1
AC2
V
SW
IN
LTC3330
1µF
SWA
6V
CAP
SWB
V
V
IN2
OUT
UV3
UV2
SCAP
UV1
BAL
UV0
BAT
IPK2
PGVOUT
IPK1
EH_ON
IPK0
OUT2
OUT1
OUT0
V
IN3
GND
Figure 12. Dust Mote Setup with a Supercapacitor,
a Battery and EH_ON Connected to OUT2
of 2.5V to the energy harvester set-point of 3.6V, V
above the 2.5V PGVOUT threshold, hence, PGVOUT will
go high every time EH_ON goes low. This cycle will be
repeated until V
OUT
V
setting of 3.6V. When a pulse load is applied that is
OUT
greater than the energy supplied by the input capacitor,
VIN will drop below the VIN_UVLO_FALLING threshold,
EH_ON will go low and the buck-boost regulator will be
ready to support the load requirement from the battery,
but will not start to switch until the supercapacitor is
discharged to 2.5V. In this way, the circuit can store a
is
lot of harvested energy and use it for an extended period
IN
of time before switching over to the battery energy. The
supercapacitor could be sized to accommodate known
OUT
repeated periods of time that the energy harvester source
will not be available, such as overnight when a vibrating
machine is turned off or in the case of a solar application,
when the lights are turned off or the sun goes down.
22µH
22µH
V
= 3.6V FOR EH_ON = 1
OUT
V
= 2.5V FOR EH_ON = 0
OUT
100µF
10V
180mF
2.5V
180mF
2.5V
HZ202F
NC7SZ58P8X
(x2)
1µF
6V
reaches the PGVOUT threshold for the
V
SUPPLY
T
X
PGOOD
EHORBAT
GND
LINEAR TECHNOLOGY DC9003A-A/B
DUST MOTE FOR WIRELESS MESH NETWORKS
is
OUT
DC2048A F12
dc2048afb
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