10
dc2151af
DEMO MANUAL DC2151A
connection to a Dust mote (Dc9003a-B)
Figure 13 shows the LTC3331 with an output supercapacitor,
a Dust Mote attached, a battery installed and EH_ON
connected to OUT2. In this configuration, when EH_ON
is low, V
OUT
will be set to 2.5V and when EH_ON is high,
V
OUT
will be set to 3.6V.
The first marker in Figure 14 is where the vibration source
was activated; V
IN
then rises above the VIN_UVLO_RISING
threshold. EH_ON will then go high causing V
OUT
to rise
towards 3.6V (V
OUT
started 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
OUT
level
of 3.6V has not been reached. As the charge on V
IN
is
being transferred to V
OUT
, V
IN
is discharging and when
V
IN
reaches its UVLO_FALLING threshold, EH_ON will go
1F
2.7V
1F
2.7V
LTC3331
DC2051A F13
AC1
V
IN
CAP
V
IN2
AC2
SWB
SWA
SW
V
OUT
SCAP
BAL
PGVOUT
EH_ON
IPK2
IPK1
IPK0
OUT2
OUT0
OUT1
V
IN3
0.1µF
6.3V
UVLO RISING = 12V*
UVLO FALLING = 11V
IPEAK_BB = 100mA
22µF
25V
1µF
6.3V
4.7µF
6.3V
UV3
UV2
UV1
UV0
BAT_IN
FLOAT1 FLOAT0 LBSEL SHIP GND
CHARGE
130k
BB_IN
BAT_OUT
V
OUT
= 3.6V FOR EH_ON = 1
V
OUT
= 2.5V FOR EH_ON = 0
22µF
6.3V
22µH
22µH
22µF
6.3V
3.45V
LiFePO
4
+
1µF
6.3V
MIDE V25W
NC7SZ58P6
×2
LINEAR TECHNOLOGY DC9003A-AB
DUST MOTE FOR WIRELESS MESH NETWORKS
PGOOD
EHORBAT
T
X
V
SUPPLY
GND
*FOR PEAK POWER TRANSFER, CENTER THE UVLO WINDOW
AT HALF THE RECTIFIED OPEN CIRCUIT VOLTAGE OF THE PIEZO
Figure 13. Dust Mote Setup with a Supercapacitor, a battery and EH_ON connected to OUT2
V
OUT
1.00V/DIV
V
IN
2.00V/DIV
PGV
OUT
5.00V/DIV
EH_ON
5.00V/DIV
200s/DIV
DC2051A F14
Figure 14. MIDE 25W Charging Output Supercapacitor from 2.5V
to 3.6 V with DUST Mote Attached
