LTC3331_15 Datasheet, PDF (29/34 Pages) Linear Technology – Nanopower Buck-Boost DC/DC with Energy Harvesting Battery Charger

LTC3331
APPLICATIONS INFORMATION
DANGEROUS AND LETHAL POTENTIALS ARE PRESENT IN OFFLINE CIRCUITS! BEFORE PROCEEDING ANY FURTHER, THE READER IS WARNED THAT
CAUTION MUST BE USED IN THE CONSTRUCTION, TESTING AND USE OF OFFLINE CIRCUITS. EXTREME CAUTION MUST BE USED IN WORKING
WITH AND MAKING CONNECTIONS TO THESE CIRCUITS. REPEAT: OFFLINE CIRCUITS CONTAIN DANGEROUS, AC LINE-CONNECTED HIGH VOLTAGE
POTENTIALS, USE CAUTION. ALL TESTING PERFORMED ON AN OFFLINE CIRCUIT MUST BE DONE WITH AN ISOLATION TRANSFORMER CONNECTED
BETWEEN THE OFFLINE CIRCUIT’S INPUT AND THE AC LINE. USERS AND CONSTRUCTORS OF OFFLINE CIRCUITS MUST OBSERVE THIS PRECAUTION
WHEN CONNECTING TEST EQUIPMENT TO THE CIRCUIT TO AVOID ELECTRIC SHOCK. REPEAT: AN ISOLATION TRANSFORMER MUST BE CONNECTED
BETWEEN THE CIRCUIT INPUT AND THE AC LINE IF ANY TEST EQUIPMENT IS TO BE CONNECTED.
DANGER HIGH VOLTAGE
3.9k 3.9k
120VAC
60Hz _{3.9k 3.9k}
18V
(OPTIONAL)
1µF
22µF
6.3V
25V
4.7µF
6.3V
UVLO RISING = 18V
UVLO FALLING = 5V
IPEAK_BB = 250mA
AC2
V_IN
CAP
V_IN2
UV3
UV2
UV1
LTC3331
AC1
SWA
SWB
SW
V_OUT
SCAP
BAL
PGVOUT
4.0V
+
3.3k
Li-ION
UV0
BAT_IN
1µF
6.3V
EH_ON
V_IN3
IPK2
IPK1
CHARGE
IPK0
OUT2
BAT_OUT
OUT1
22µF
BB_IN
OUT0
6.3V
FLOAT0 FLOAT1 LBSEL SHIP GND
22µH
22µH
0.1µF
6.3V
3.3V
22µF
6.3V
3331 F10
Figure 10. AC Line Powered 5V UPS
on the last page of this data sheet shows the EH_ON output
tied to the OUT2 input. When EH_ON is low the output is
programmed to 2.5V and the battery powers the output.
When energy harvesting is available EH_ON is high and
the output is programmed to 3.6V allowing for increased
storage of harvested energy. If energy harvesting goes
away, the output is again programmed to 2.5V and the
buck-boost converter will be in sleep until the output is
discharged to the wake-up threshold. If the energy stored
at 3.6V is enough to ride through a temporary loss of
energy harvesting then the only drain on the battery will
be the quiescent current in sleep.
For more information www.linear.com/LTC3331
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