Linear Technology Corp. announced the LTC3109, a highly integrated
step-up dc/dc converter and power management IC designed to start up and run
from millivolt input voltage sources such as thermoelectric generators (TEGs)
and thermopiles. The device's groundbreaking and proprietary auto-polarity
topology allows it to generate usable power from input voltages as low as ±30mV, enabling temperature differences as low as ±1C to be harvested in lieu
of traditional battery power. This makes it ideal for energy harvesting
applications in which the input voltage polarity is unknown or is subject to
reversal. Energy harvesters are well suited for applications requiring low
average power, even with periodic pulses of higher load current. For example,
in many wireless sensor applications the circuitry is only powered to take
measurements and transmit data periodically with a low duty cycle.
The LTC3109 uses two standard compact step-up
transformers to provide a complete power management solution. Its 2.2V LDO can
power an external microcontroller, and its main output is pin selectable to one
of four (2.35, 3.3, 4.1 or 5V) fixed voltages to power a sensor, data
acquisition circuits and/or a wireless transmitter. A second switched output
can be enabled by the host in order to power devices that do not have a
micropower shutdown capability. The addition of a storage capacitor provides
continuous power even when the input energy source is unavailable or
intermittent. The LTC3109's extremely low quiescent current (less than 7µA) and
high efficiency design ensure the fastest possible charge times for the output
reservoir capacitor. The combination of the LTC3109's leadless 4mm x 4mm QFN-20
package (or leaded SSOP-20) and very small external components ensure a highly
compact solution for energy harvesting applications.
The LTC3109EUF is available in a 20-lead 4mm
x 4mm QFN package and the LTC3109EGN is available in a SSOP-20 package. Pricing
starts at $3.95 each for 1,000-piece quantities. Industrial temperature grade
versions, the LTC3109IUF and LTC3109IGN, are also available, priced starting at
$4.65 each for 1,000-piece quantities. All versions are available from stock.
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