LT1673 LINER [Linear Technology], LT1673 Datasheet - Page 13

• Manufacturer Part Number: LT1673
• Description: Auto-Polarity, Ultralow Voltage Step-Up Converter
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
Table 3. Peltier Cell Manufacturers
CUI Inc
www.cui.com
Ferrotec
www.ferrotec.com/products/thermal/modules/
Fujitaka
www.fujitaka.com/pub/peltier/english/thermoelectric_power.html
Hi-Z Technology
www.hi-z.com
Kryotherm
www.kryotherm
Laird Technologies
www.lairdtech.com
Micropelt
www.micropelt.com
Nextreme
www.nextreme.com
TE Technology
www.tetech.com/Peltier-Thermoelectric-Cooler-Modules.html
Tellurex
www.tellurex.com/
TEG LOAD MATCHING
The LTC3109 was designed to present an input resistance
(load) in the range of 2Ω to 10Ω, depending on input volt-
age, transformer turns ratio and the C1A and C2A capacitor
values (as shown in the Typical Performance curves). For
a given turns ratio, as the input voltage drops, the input
resistance increases. This feature allows the LTC3109 to
optimize power transfer from sources with a few Ohms
of source resistance, such as a typical TEG. Note that a
lower source resistance will always provide more output
current capability by providing a higher input voltage
under load.
Table 4. Recommended TEG Part Numbers by Size
MANUFACTURER
CUI Inc. (Distributor)
Ferrotec
Fujitaka
Kryotherm
Laird Technology
Marlow Industries
Tellurex
TE Technology
9501/031/030 B
TE-31-1.0-1.3
FPH13106NC
C2-15-0405
CP60133
15mm
9501/071/040 B
TE-31-1.4-1.15
FPH17106NC
C2-20-0409
RC3-8-01
CP60233
20mm
UNIPOLAR APPLICATIONS
The LTC3109 can also be confi gured to operate from two
independent unipolar voltage sources, such as two TEGs
in different locations. In this confi guration, energy can be
harvested from either or both sources simultaneously. See
the Typical Applications for an example.
The LTC3109 can also be confi gured to operate from a
single unipolar source, using a single step-up transformer,
by ganging its V
it can extract the most energy from very low resistance
sources. See Figure 3 for an example of this confi guration,
along with the performance curves.
PELTIER CELL (TEG) SUPPLIERS
Peltier cells are available in a wide range of sizes and power
capabilities, from less than 10mm square to over 50mm
square. They are typically 2mm to 5mm in height. A list
of some Peltier cell manufacturers is given in Table 3 and
some recommended part numbers in Table 4.
COMPONENT SELECTION
Step-Up Transformer
The turns ratio of the step-up transformers will determine
how low the input voltage can be for the converter to start.
Due to the auto-polarity architecture, two identical step-up
transformers should be used, unless the temperature drop
across the TEG is signifi cantly different in one polarity, in
which case the ratios may be different.
PT6.7.F2.3030.W6
TGM-127-1.0-0.8
9500/097/090 B
TE-71-1.4-1.15
IN
FPH17108AC
C2-30-1505
RC6-6-01
CP60333
and SW pins together. In this manner,
30mm
PT8.12.F2.4040.TA.W6
LCB-127-1.4-1.15
TE-127-1.4-1.05
9500/127/100 B
LTC3109
FPH112708AC
RC12-8-01LS
C2-40-1509
CP85438
40mm
13
3109fa