LTC3330_15 Datasheet, PDF (25/32 Pages) Linear Technology – Nanopower Buck-Boost DC/DC with Energy Harvesting Battery Life Extender

LTC3330
APPLICATIONS
When paired with the 550nA LTC4071 shunt battery charger
with low battery disconnect the LTC3330 can charge a bat-
tery from an energy harvesting source as shown in Figure 8.
A battery is connected to the BAT pin of the LTC4071. If
the battery voltage drops below a selected level the battery
will be disconnected and protected from further discharge.
A charging resistor is connected from V_IN of the LTC3330
to V_CC of the LTC4071 to create a charging path. V_CC is
then the input to the LTC3330 buck-boost at the BAT pin.
The charging resistor should be sized in accordance with
the available energy from the energy harvesting source
to allow the V_IN pin voltage of the LTC3330 to reach the
UVLO rising threshold and prioritize powering the output
at V_OUT.
Higher Efficiency Battery Powered Buck
If the battery voltage will always be higher than the regu-
lated output of the LTC3330 then the battery powered
buck-boost will always run in buck mode. In this case the
inductor that is usually placed between SWA and SWB
can go directly to V_OUT from SWA, bypassing internal
switch M4 of the buck-boost (Figure 9). This will reduce
conduction losses in the converter and improve the ef-
ficiency at higher loads.
MIDE V25W
22µF
25V
4.7µF, 6.3V
1µF, 6.3V
AC2
V_IN
CAP
V_IN2
LTC3330
AC1
SW
V_OUT
SCAP
330k
UV3
UV2
UVLOR = 12V*
UVLOF = 11V
UV1
IPEAK_BB = 25mA
UV0
BAL
LDO_IN
LDO2
LDO1
BAT ^VCC
ADJ
LTC4071
NTC
LBSEL
GND
+
Li-ION
220µH
4.7µF
6.3V
BAT
SWA
LDO0
LDO_EN
PGVOUT
PG_LDO
SWB
EH_ON
LDO_OUT
GND
V_IN3
IPK2 IPK1 IPK0 OUT2 OUT1 OUT0
22µH
3.3V
22µF
6.3V
1.8V
1µF
22µF
6.3V
6.3V
3330 F08
*FOR PEAK POWER TRANSFER, CENTER THE UVLO WINDOW
AT HALF THE RECTIFIED OPEN CIRCUIT VOLTAGE OF THE PIEZO
Figure 8. Energy Harvesting Battery Charger with Low Battery Disconnect
For more information www.linear.com/LTC3330
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