MB39C831 Datasheet, PDF (22/40 Pages) Cypress Semiconductor – Ultra Low Voltage Boost Power Management IC for Solar/Thermal Energy Harvesting Datasheet

MB39C831
First of all, apply the following equation and calculate energy consumption for an application from voltage, current, and time
during an operation.
The energy stored on a capacitor is calculated by the following equation.
Since the energy in a capacitor is proportional to the square of the voltage, it is energetically advantageous for the boost
DC/DC converter, the input voltage, is less than the output voltage, to make the Cout larger.
The Cin and the Cout are sized so as to satisfy the following equation (refer to Figure 9-1). The η, the efficiency of the
MB39C831, is determined from the graph of the efficiency shown in Figure 10-1
dECin and dECout are the available energies for the application.
Figure 9-1 Example of Energy Harvesting System
Harvester
VDD
Cin _MB39C831
VDD
0.3V
0V
Efficiency(η)
Available Energy
+
VDD : VDD input voltage
0.3V : Min VDD input voltage
Total Energy
VOUT
VOUT
VOMIN
0V
Cout
Appli.
VOUT : Preset output voltage
VOMIN : Min. operating voltage of an application
Before calculating the initial charging time (TInitial), calculate the total energy (ECin and ECout) stored on both Cin and Cout.
PHarvester is a power generation capability of a harvester. An initial charging time (TInitial) is calculated by the following equation.
Repeat charging time (TRepeat) is calculated by the following equation. The TRepeat become shorter than TInitial.
Document Number: 002-08404 Rev *A
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