MB39C831 Datasheet, PDF (21/40 Pages) Cypress Semiconductor – Ultra Low Voltage Boost Power Management IC for Solar/Thermal Energy Harvesting Datasheet

MB39C831
9. Application Notes
Inductor
The MB39C831 is optimized to work with an inductor in the range of 4.7 µH. Select a value of 4.7 µH. Also, select an inductor
with a DC current rating which can permit the peak current for the inductor.
The peak current for the inductor in steady state operation (ILMAX) can be calculated by the following equation according to
the maximum current of harvesters (IINMAX).
Harvester (Photovoltaic Power Generator)
In case of photovoltaic (or solar) energy harvesting, use a solar cell with an open-circuit voltage less than 4.75V and the preset
output voltage. Electric power obtained from a solar or light is increased in proportion to the ambient illuminance.
Silicone-based solar cells are single crystal silicon solar cell, polycrystalline silicon solar cell, and amorphous silicon solar cell.
Organic-based solar cells are dye-sensitized solar cell (DSC), and organic thin film solar cell. Crystal silicon and polycrystalline
silicon solar cells have high energy conversion efficiency. Amorphous silicon solar cells are lightweight, flexible, and produced
at low cost. Dye-sensitized solar cells are composed by sensitizing dye and electrolytes, and are low-cost solar cell. Organic
thin film solar cells are lightweight, flexible, and easily manufactured.
Harvester (Temperature Difference Power Generator)
Temperature difference power generators produce electric power keeping temperature difference between the high
temperature side and the low temperature side. The temperature difference power generators include the peltier elements
utilizing the Seebeck effect and thermopiles that made of thermocouples in series or in parallel.
Sizing of Input and Output Capacitors
Common capacitors are layered ceramic capacitor, electrolytic capacitor, electric double layered capacitor (EDLC), and so on.
Electrostatic capacitance of layered ceramic capacitors is relatively small. However, layered ceramic capacitors are small and
have high voltage resistance characteristic. Electrolytic capacitors have high electrostatic capacitance from µF order to mF
order. The size of capacitor becomes large in proportion to the size of capacitance. Electric double layered capacitors have
high electrostatic capacitance around 0.5F to 1F, but have low voltage resistance characteristics around 3V to 5V. Be very
careful with a voltage resistance characteristic. Also, leak current, equivalent series resistance (ESR), and temperature
characteristic are criteria for selecting,
Table 9-1 Manufactures of Capacitors
Part Number/Series Name
EDLC351420-501-2F-50
EDLC082520-500-1F-81
EDLC041720-050-2F-52
Gold capacitor
Type, Capacitance
EDLC, 500 mF
EDLC, 50 mF
EDLC, 5 mF
EDLC
Manufacture
TDK Corporation
Panasonic Corporation
Energy from harvester should be stored on the Cin and Cout to operate the application block. If the size of these capacitors
were too big, it would take too much time to charge energy into these capacitors, and the system cannot be operated
frequently. On the other hand, if these capacitors were too small, enough energy cannot be stored on these capacitors for the
application block. The sizing of the Cin and Cout is important.
Document Number: 002-08404 Rev *A
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