Linear Technology DC2048A Manual page 9

connection to a Dust mote (Dc9003a-B)
Figure 10 shows the LTC3330 with a supercapacitor on
the output, a battery installed and the output voltage set
to 3.6V. The scope shots in Figure 11 were taken after
applying a pulsed load of 15mA for 10ms. With the battery
attached and a pulsed load applied, the EH_ON signal will
switch back and forth from high to low every time the
V voltage transitions from the VIN_UVLO_RISING to
IN
VIN_UVLO_FALLING threshold. When the pulsed load is
22µF 1µF
25V 6V
4.7µF , 6V
+
PRIMARY 22µF
CELL 6V
3.2V
Figure 10. LTC3330 Circuit with a Supercapacitor, a Battery Installed
and a Pulsed Load Applied (V
EH_ON
5V/DIV
V
OUT
50mV/DIV
V
IN
2V/DIV
LOAD CURRENT
20mA/DIV
Figure 11. Charging a Supercapacitor with a Battery Installed and a
Pulsed Load (V = 3.6V)
OUT
DEMO MANUAL DC2048A
applied, the output capacitor is depleted slightly and the
input capacitor must recharge the output cap. Because the
input capacitance is much less than the output capacitance,
the input capacitor will go through many UVLO transitions to
charge the output capacitor back up to the sleep threshold.
Once the output is charged to the output sleep threshold,
the EH_ON signal will again be consistently high indicating
that the energy harvesting source is powering the output.
PIEZO
MIDE V25W
AC1 AC2
22µH
V SW
IN
22µH
LTC3330
SWA
CAP SWB
V V
IN2 OUT
UV3
UV2
SCAP
UV1
BAL
UV0
BAT
PGVOUT
EH_ON
IPK2
IPK1
IPK0
OUT2
OUT1
OUT0
V
IN3
GND
= 3.6V)
OUT
DC2048A F11
1s/DIV
PULSED
100µF
15mA
10V
10ms
180mF
2.5V
180mF
2.5V
HZ202F
1µF
6V
DC2048A F10
dc2048afb
9