Components

PMIC for Energy Harvesting Powers Typical Wireless Sensor

E-Peas introduced a PMIC for energy harvesting devices that integrates all the active elements for powering a typical wireless sensor node. The AEM10941 extracts dc power from up to 7-cell solar panels to simultaneously store energy in a rechargeable element and supply the system with two independent regulated voltages.

Applications for the PMIC include PV cell harvesting, home automation, industrial monitoring, e-health monitoring, geolocation, and wireless sensor nodes.

The AEM10941 allows an extension of battery lifetime and ultimately eliminates the primary energy storage element in a large range of wireless applications, such as industrial monitoring, geolocation, home automation, e-health monitoring and wireless sensor nodes.

The AEM10941 harvests the available input current up to 110mA. An integrated, ultra-low power boost converter charges a storage element, such as a Li-ion battery, a thin film battery, a supercapacitor, or a conventional capacitor. The boost converter operates with input voltages from 50mV to 5V.

Its cold-start circuit lets the device start operating with empty storage elements at an input voltage as low as 380mV and an input power of just 3µW. The low-voltage supply typically drives a microcontroller at 1.2V or 1.8V. The high-voltage supply may drive a radio transceiver at a configurable voltage between 1.8V and 4.1V. Both are driven by highly-efficient LDO regulators for their low noise and high stability.

The company says that the device works with any battery or supercapacitor charging. The device integrates a balun for a dual-cell supercapacitor The PMIC offers fast supercapacitor charging. It warns the load when the battery (or supercapacitor) is running low, and it warns when output voltage regulators are available.

The PMIC automatically switches to the primary battery when the secondary battery is exhausted.

Configuration pins determine various operating modes by selecting the voltage of the high-voltage supply and the low-voltage supply and by setting predefined conditions for the energy storage element (overcharge or over-discharge voltages).

Moreover, special modes can be obtained at the expense of a few configuration resistors.

Five capacitors and two inductors are required, available respectively in the small 0402 and 0603 SMD

formats. With only seven external components, integration is maximized, footprint and BOM are minimized, and the design can also reduce time to market.

Solar energy harvesting block diagram

Ultra-low power start-up
  • Cold start from 380mV input voltage and 3μW input power (typical)
Ultra-low power boost regulator
  • Open-circuit voltage sensing for MPPT every 5s
  • Configurable MPPT with 2-pin programming
  • Selectable Voc ratios of 70%, 75%, 85%, or 90%
  • Input voltage operation range from 50mV to 5V
  • MPPT voltage operation range from 50mV to 5V
Integrated 1.2/1.8V LDO regulator
  • Up to 20mA load current
  • Power gated dynamically by external control
  • Selectable output voltage
Integrated 1.8 V to 4.1V LDO regulator
  • Up to 80mA load current with 300mV drop-out
  • Power gated dynamically by external control
  • Selectable or adjustable output voltage
Flexible energy storage management
  • Selectable over-charge and over-discharge protection
  • For any type of rechargeable battery or supercapacitor
  • Fast supercapacitor charging
  • Warns the load when battery is running low
  • Warns when output voltage regulators are available
Smallest footprint, smallest BOM
  • Only seven passive external components
Optional primary battery
  • Automatically switches to the primary battery when the secondary battery is exhausted
  • Integrated balun for dual-cell supercapacitor
e-peas semiconductor
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