FEATURES
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LTC3109
Auto-Polarity, Ultralow
Voltage Step-Up Converter
and Power Manager
DESCRIPTION
The LTC
®
3109 is a highly integrated DC/DC converter ideal
for harvesting surplus energy from extremely low input
voltage sources such as TEGs (thermoelectric genera-
tors) and thermopiles. Its unique, proprietary autopolarity
topology* allows it to operate from input voltages as low
as 30mV, regardless of polarity.
Using two compact step-up transformers and external
energy storage elements, the LTC3109 provides a com-
plete power management solution for wireless sensing
and data acquisition. The 2.2V LDO can power an external
microprocessor, while the main output can be programmed
to one of four fixed voltages. The power good indicator
signals that the main output is within regulation. A second
output can be enabled by the host. A storage capacitor (or
battery) can also be charged to provide power when the
input voltage source is unavailable. Extremely low quies-
cent current and high efficiency maximizes the harvested
energy available for the application.
The LTC3109 is available in a small, thermally enhanced
20-lead (4mm
×
4mm) QFN package and a 20-lead SSOP
package.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
*Patent pending.
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Operates from Inputs as Low as ±30mV
Less Than ±1°C Needed Across TEG to Harvest
Energy
Proprietary Auto-Polarity Architecture
Complete Energy Harvesting Power Management
System
– Selectable V
OUT
of 2.35V, 3.3V, 4.1V or 5V
– 2.2V, 5mA LDO
– Logic-Controlled Output
– Energy Storage Capability for Operation During
Power Interruption
Power Good Indicator
Uses Compact Step-up Transformers
Small, 20-lead (4mm
×
4mm) QFN Package or
20-Lead SSOP
APPLICATIONS
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Remote Sensor and Radio Power
HVAC Systems
Automatic Metering
Building Automation
Predictive Maintenance
Industrial Wireless Sensing
TYPICAL APPLICATION
TEG
(THERMOELECTRIC GENERATOR)
±30mV TO ±500mV
1:100
1nF
V
OUT
Current vs TEG Voltage
C1A
V
OUT2
OPTIONAL SWITCHED OUTPUT FOR SENSORS
3.3V
2.2V
•
47μF
•
470pF
900
800
C2A
SWA
V
INA
C1B
470pF
C2B
V
OUT
VLDO
+
470μF
2.2μF
700
LOW POWER
RADIO
1:100 TRANSFORMERS
C1A = C1B = 1nF
V
OUT
= 3.3V
600
I
VOUT
(μA)
500
400
300
200
1nF
1:100
LTC3109
μP
PG00D
•
•
SENSOR(S)
VAUX
SWB V
OUT2_EN
V
INB
VS1
VSTORE
VAUX
VS2
GND
5.25V
1μF
100
+
C
STORE
3109 TA01a
0
–300
–200
–100
0
100
V
TEG
(mV)
200
300
3109 TA01b
3109fa
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
