Energy harvester dc-dc can run from two ambient sources

E-peas has created a power IC that can mediate between two energy harvesters, a 5V charger, a power store and a load.

AEM13920 can work from any combination of two sources including: photo-voltaic cells, thermo-electric generators, RF energy harvesters or kinetic pulsed sources.

“For instance, a remote control could have separate PV cells on its front and rear, to maintain an energy input whether the device is left face up or face down,” said the company. “A smart wireless light switch could operate on mechanical energy for short RF transmissions, and on stored mechanical or light energy for longer operations such as downloading and installing a firmware update.”

Source-to-storage and storage-to-load conversion efficiencies of >90% are claimed, and there are tracking algorithms for each source that attempt to increase extracted energy, or there is constant source voltage regulation.

Cold-start is possible from as little as 275mV if 5µW of power is available.

The 5V input is included to charge the energy store if it is a battery “This compact and ultra-efficient battery charger allows for
extending battery lifetime and eliminating the primary energy storage in a large range of applications,” said e-peas.

Batteries including Li-polymer, LiFP and Li-ceramic batteries can be accomodates, as can hybrid lithium capacitors.

Configurable thresholds prevent over-charging or over-discharging the storage element, whether it is a battery or super-cap, and there is storage thermal monitoring too.

“Average power monitoring system allows the application circuit to get a measure of the energy harvested from each source to
the battery and from the battery to the application circuit”, and “a shipping mode is available to avoid charging and discharging
of the storage element during shipping or storage,” said e-peas.

The load gets its adjustable (600mV to 2.5V) supply from a built-in buck regulator, and I²C communication is provided to connect with the host microcontroller.

Packaging is 5 x 5mm 40pad QFN, and there is an evaluation board called 2AAEM13920J051