The following document contains information on Cypress products. Energy Calculation For Energy Harvesting APPLICATION NOTE Publication Number CONFIDENTIAL AN405-00001 Revision 1.0 Issue Date July 18, 2014 A P P L I C A T I O N N O T E Target Products This application note applies to the following products. (Buck DC/DC converter) Part number MB39C811 Description Ultra Low Power Buck Power Management IC for Solar/Vibrations Energy Harvesting (Boost DC/DC converter) Part number MB39C831 2 CONFIDENTIAL Description Ultra Low Voltage Boost Power Management IC for Solar/Thermal Energy Harvesting AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N N O T E Table of Contents 1. Introduction .............................................................................................................................................. 5 1.1 Energy harvesting system .............................................................................................................. 5 2. Energy Calculation .................................................................................................................................. 6 2.1 Energy requirement in application block ......................................................................................... 6 2.2 Sizing of Cin and Cout (for MB39C811) ......................................................................................... 7 2.3 Charging time of Cin and Cout (for MB39C811) ............................................................................. 8 2.4 Sizing of Cin and Cout (for MB39C831) ......................................................................................... 9 2.5 Charging time for Cin and Cout (for MB39C831) .......................................................................... 10 3. Appendix ................................................................................................................................................ 11 3.1 Power generation capability ......................................................................................................... 11 3.2 Amorphous silicon solar cell (for MB39C811) ............................................................................... 12 3.3 Amorphous silicon solar cell in series (for MB39C811) ................................................................ 15 3.4 Piezo (for MB39C811) .................................................................................................................. 17 3.5 Single crystal silicon solar cell -1- (for MB39C831) ...................................................................... 19 3.6 Single crystal silicon solar cell -2- (for MB39C831) ...................................................................... 20 3.7 Peltier (for MB39C831) ................................................................................................................. 21 Figures Figure 1-1 Figure 2-1 Figure 2-2 Figure 2-3 Figure 2-4 Figure 2-5 Figure 2-6 Figure 3-1 Figure 3-2 Figure 3-3 Figure 3-4 Figure 3-5 Figure 3-6 Figure 3-7 Figure 3-8 Figure 3-9 Figure 3-10 Figure 3-11 Figure 3-12 Figure 3-13 Figure 3-14 Figure 3-15 Figure 3-16 Figure 3-17 Figure 3-18 Popular energy harvesting system ......................................................................................... 5 Measurement of energy requirement...................................................................................... 6 Waveform of VOUT and IVOUT ............................................................................................. 6 Stored Image of capacitors (for MB39C811) .......................................................................... 7 Charging time of Cin and Cout (for MB39C811) ..................................................................... 8 Stored Image of capacitors (for MB39C831) .......................................................................... 9 Charging time of Cin and Cout (for MB39C831) ................................................................... 10 Power generation capability .................................................................................................. 11 Block diagram with Amorphous silicon solar cell .................................................................. 12 Charging time for Cin and Cout ............................................................................................ 12 Block diagram with Amorphous silicon solar cell .................................................................. 13 After the Charging time of Cin and Cout ............................................................................... 13 Characteristic of amorphous silicon solar cell ....................................................................... 14 Block diagram with 2 series Amorphous silicon solar cells ................................................... 15 Measured graph using amorphous silicon solar cells in series ............................................. 15 Measured graph using amorphous silicon solar cell in series ............................................... 16 Energy vs input voltage in capacitor ................................................................................... 16 Testing method using Piezo ................................................................................................ 17 Measured graph using Piezo .............................................................................................. 17 Block diagram with Single crystal silicone solar cell -1- ...................................................... 18 Measured graph using Single crystal silicone solar cell -1- ................................................ 19 Block diagram with Single crystal silicone solar cell -1- ...................................................... 19 Measured graph using Single crystal silicone solar cell -2- ................................................ 20 Block diagram with single crystal silicone solar cell -2- ...................................................... 20 Block diagram with Peltier .................................................................................................. 21 Tables Table 3-1 Table 3-2 Table 3-3 Examples of power generation capability (for MB39C811) ...................................................... 11 Examples of power generation capability (for MB39C831) ..................................................... 11 Characteristics of Amorphous silicon solar cell ...................................................................... 12 July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 3 A P P L I C A T I O N Table 3-4 Table 3-5 Table 3-6 Table 3-7 Table 3-8 4 CONFIDENTIAL N O T E Characteristics of 2 series Amorphous silicon solar cells ....................................................... 15 Characteristics of Piezo ......................................................................................................... 17 Characteristics of single crystal silicone solar cell -1- ............................................................ 19 Characteristics of single crystal silicone solar cell -2- ............................................................ 20 Characteristics of Peltier ........................................................................................................ 21 AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N N O T E 1. Introduction For the energy harvesting, the system design is very important. The system performing low power operation should be designed since the amount of energy from harvester is very small. In such cases, the energy budget calculation is necessary. 1.1 Energy harvesting system Figure 1-1 shows the popular energy harvesting system. Figure 1-1 Popular energy harvesting system Enveronmental Energy Power Good VIN Harvester Block Cin VOUT PMIC Block Cout Power Gating Application Block MCU RF Sensor Low power consumption devices are needed to design the energy harvesting system. Select low power PMIC and ICs for the application block because the energy from harvester is limited. Also, 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, too. July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 5 A P P L I C A T I O N N O T E 2. Energy Calculation 2.1 Energy requirement in application block Once the system is designed, make the prototype. The Figure 2-1 shows the measurement method of the energy requirement in application block. Figure 2-1 Measurement of energy requirement Power Good VIN Power Source Cin VOUT PMIC Block Current Probe Power Gating Cout V Application Block MCU RF Sensor To calculate the necessary energy for the application, measure the voltage and current of VOUT. After the measurement, apply the following equation to calculate the energy requirement. EAppli. [J] = VAppli. × IAppli. × t Appli. The Figure 2-2 shows actual measurement waveform of the energy harvesting system. In this example, the energy requirement for the application block is roughly calculated at 2,534µJ. Figure 2-2 Waveform of VOUT and IVOUT Waveforms VIN ≧ 5.2V Preset output voltage = 3.3V VOUT 2V/DIV 3.3V Power good off MCU & Sensor IVOUT 10mA/DIV MCU RF transmission 3.3V x 16mA x 48ms =2534µJ 16mA 48ms Application Operation starts 10ms/DIV 6 CONFIDENTIAL AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N 2.2 N O T E Sizing of Cin and Cout (for MB39C811) The Cin and Cout should be sized. The Figure 2-3 shows the image of the capacitors with the buck DC/DC converter, MB39C811. Figure 2-3 Stored Image of capacitors (for MB39C811) Power Good VIN Power Source VIN≧5.2V Buck DC/DC VOUT=3.3V Power Gating Application MB39C811 VUVLOH VUVLOL Cin 0V Cout =47µF VVOUT VOPGL 0V 2534µJ Efficiency=80% Available Energy VUVLOH : UVLO release voltage VUVLOL : UVLO detection voltage VVOUT VOPGL : Preset output voltage : Output power-good reset voltage The energy stored on a capacitor is calculated by the following equation. 1 Ecapacitor [J] = CV 2 2 Because the energy in a capacitor is proportional to the square of the voltage, it is energetically advantageous for the buck DC/DC converter to make the Cin larger. On the other hand, for the boost DC/DC converter, it is energetically advantageous to make the Cout larger. In the example with MB39C811 of the Figure 2-3, adjust the Cin, and keep the Cout = 47µF (refer to the MB39C811 datasheet). Calculate the available energy in Cout The output power-good reset voltage (minimum voltage of the Cout) is 70 % of the preset output voltage (VOUT voltage), VOPGL is 2.31V (refer to the MB39C811 datasheet). Available energy in Cout [μJ] = 1 × Cout × (VVOUT 2 − VOPGL2 ) 2 Available energy in Cout [μJ] = 1 × 47[μF] × (3.3[V]2 − 2.31[V]2 ) = 131[μJ] 2 In the Figure 2-2, the energy requirement for the application block was calculated at 2,534[µJ]. The available energy stored on the Cout was found 131µJ, so that the remaining energy requirement is Remaining energy requirement [μJ] = 2,534[μJ] − 131[μJ] = 2,403[μJ] 1 2 The remaining energy requirement should be stored on the Cin. Calculate the size of the Cin For the Cin calculation, it is necessary to take the efficiency of PMIC into account. According to the datasheet, the efficiency is about 80% in the 16mA load current. (The “η” is the efficiency of PMIC.) Available energy in Cin [μJ] = 1 × η × Cin × (VUVLOH 2 − VUVLOL2 ) 2 Available energy i2403 [μJ] = 1 × 80[%] × Cin[μF] × (5.2[V]2 − 4.0[V]2 ) 2 Available energy in Cin [μF] = 544[μJ] July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 1 2 7 A P P L I C A T I O N 2.3 N O T E Charging time of Cin and Cout (for MB39C811) In order to calculate the charging time, the power generation capability is needed. (Refer to the Appendix, e.g. a solar cell has 155µW generation capability at the 1000[lx]). The Figure 2-4 shows the example of energy harvesting system focused on the charging time with a harvester. Figure 2-4 Charging time of Cin and Cout (for MB39C811) Light(1000[lx]) Power Good 155µW Amorphous Si solar cell VIN Cin =544µF Buck DC/DC MB39C811 VOUT Power Gating Application 2534µJ Cout =47µF Efficiency=80% Step1 for Initial charging time Before calculating the initial charging time, calculate the total energy stored on both Cin and Cout. Total energy of Cin [μJ] = 1 1 × Cin × (VUVLOH 2 ) = × 544[μF] × 5.2[V]2 = 7355[μJ] 2 2 Total energy of Cout [μJ] = 1 1 × Cout × (VVOUT 2 ) = × 47[μF] × 3.3[V]2 = 256[μJ] 2 2 Step2 for Initial charging time Initial charging time of Cin [s] = Total energy of Cin [μJ] 7355 [μJ] = = 49.5[sJ] Power of solar cell [μW] 155 [μW] Initial charging time of Cout [s] = Total energy of Cout [μJ] 256 [μJ] = = 2[sJ] Power of solar cell [μW] × 80[%] 155 [μW] × 0.8 Initial charging time [s] = Initial charging time of Cin [s] + Initial charging time in Cout [s] Initial charging time [s] = 49.5 [s] + 2 [s] = 51.5 [s] 1 2 1 2 Repeat charging time Repeat time for charging time of Cin [s] = Repeat charging time of Cout [s] = Available energy in Cin [μJ] 2403 [μJ] = = 15.5[sJ] Power of solar cell [μW] 155 [μW] Available energy in Cout [μJ] 131 [μJ] = = 1[sJ] Power of solar cell [μW] × 80[%] 155 [μW] × 0.8 Repeat charging time [s] = Repeat charging time of Cin [s] + Repeat charging time of Cout [s] Repeat charging time [s] = 15.5 [s] + 1 [s] = 16.5 [s] 8 CONFIDENTIAL 1 2 1 2 AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N 2.4 N O T E Sizing of Cin and Cout (for MB39C831) The Figure 2-5 shows the image of the capacitors with the boost DC/DC converter, MB39C831. Figure 2-5 Stored Image of capacitors (for MB39C831) DET[1:0] VDD Power Source Boost DC/DC VOUT=3.3V MB39C831 VDD≧0.35V VDD 0.3V 0V Cin =10µF Efficiency=70% Power Gating Application 2534µJ VOUT 2.9V Cout =470µF 0V Available Energy VDD : VDD input voltage 0.3V : Min VDD input voltage VOUT 2.9V : : Preset : output voltage Output : power-good reset voltage Because the energy in a capacitor is proportional to the square of the voltage, it is energetically advantageous for the boost DC/DC converter to make the Cout larger. In the example with MB39C831 of the Figure 2-5, only adjust the Cout. Although the Cin = 10µF is used as the input capacitor, the Cin is excluded from the energy calculation because the stored energy on the Cin is very small. In the Figure 2-2, the energy requirement for the application block was calculated at 2,534[µJ]. The energy requirement should be stored on the Cout. Calculate the size of the Cout The output power-good reset voltage (minimum voltage of the Cout) is set by 2.9V in MB39C831. (Refer to the MB39C831 datasheet). Available energy in Cout [μJ] = 1 × Cout × (VOUT 2 − 2.9[V]2 ) 2 Available energy i 2534 [μJ] = 1 × Cout[μF] × (3.3[V]2 − 2.9[V]2 ) 2 Available energy in Cout [μF] = 2044[μF] July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 1 2 9 A P P L I C A T I O N 2.5 N O T E Charging time for Cin and Cout (for MB39C831) In order to calculate the charging time, the power generation capability is needed. (Refer to the Appendix, e.g. the single crystal silicon solar cell (Vmax=0.5V) has 233µW generation capability including the MB39831’s consumption at the 50000[lx]). The Figure 2-6 shows the example of energy harvesting system focused on the charging time with a harvester. Figure 2-6 Charging time of Cin and Cout (for MB39C831) Light(50000[lx]) Power Good Single crystal Si solar cell VIN Cin =10µF (Vmax=0.5V) Boost DC/DC MB39C831 233µW VOUT Power Gating Cout =2044µF Application 2534µJ Step1 for Initial charging time Before calculating the initial charging time, calculate the total energy stored on the Cout.(excluding the Cin because the stored energy on the Cin is very small.) Total energy of Cout [μJ] = 1 1 × Cout × (VOUT 2 ) = × 2044[μF] × 3.3[V]2 = 11127[μJ] 2 2 Step2 for Initial charging time Initial charging time of Cout [s] = Total energy of Cout [μJ] 11127 [μJ] = = 44.8[s] generation capability including IC[μW] 233 [μW] Repeat charging time Repeat charging time of Cout [s] = 10 CONFIDENTIAL Available energy in Cout [μJ] 2534 [μJ] = = 11[s] generation capability including IC[μW] 233 [μW] AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N N O T E 3. Appendix 3.1 Power generation capability Figure 3-1 Power generation capability INPUT Harvester Cin OUTPUT DC/DC Cout To make it simple to calculate charging time at the section 2.3 and the section 2.5, the power generation capability is calculated based on the measured charging time of capacitors. Table 3-1 Generator Solar Solar Piezo Type Amorphous Si Examples of power generation capability (for MB39C811) Size Vmax Imax [mm] [V] [mA] 46×30 6.68 (6.4 + 0.28) Amorphous 46×30 13.08 Si (2 series) (12.8 + 0.28) Polymer 80×30 80(Vpp) condition Power generation capability [µW] --- 1000[lx] 155 [µW] --- 1000[lx] 193 [µW] --- 3Hz 578 [µW] hand push The MB39C831 is designed for harvesters that have a high power generation capability, such as an outdoor solar cell. It is not possible to start up with a small indoor solar cell. Table 3-2 Generator Solar Solar Peltier Type Single crystal Si Single crystal Si --- Examples of power generation capability (for MB39C831) Size Vmax Imax [mm] [V] [mA] 50×50 0.5 500 50000[lx] 233 [µW] (*1) 82×68 1.5 500 50000[lx] 1706 [µW] (*1) 0.704 117 ΔT=30℃ Larger than 44000 [µW] (*2) 10×10 (2 series) condition Power generation capability [µW] *1: the value including the MB39C831’s consumption. *2: the value from a peltier’s datasheet July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 11 A P P L I C A T I O N 3.2 N O T E Amorphous silicon solar cell (for MB39C811) Table 3-3 Generator Solar Size Vmax Imax [mm] [V] [mA] 46×30 6.68 --- Type Amorphous Si Characteristics of Amorphous silicon solar cell Figure 3-2 Power generation condition capability [µW] 1000[lx] 155 [µW] Block diagram with Amorphous silicon solar cell Light(1000[lx]) 155µW VIN Solar Cell 46mm×30mm 9 cells Vf=0.28V MB39C811 VUVLOH VVOUT Cin =470µF 0V Cout =47µF 0V VUVLOH : UVLO release voltage Figure 3-3 VOUT=3.3V Buck DC/DC VVOUT : Preset output voltage Charging time for Cin and Cout Amorphous Si solar cell 8 9 cells, Size: 46x30mm Voltage [V] Preset output voltage = 3.3V 7 Illuminance = 1000lx transfer of energy Cin = 470µF from Cin to Cout 6 Cout = 47µF 5 4 42s VIN 3.3V 3 2 1 41s VOUT 0 0 5 10 15 20 25 30 Time [s] 35 40 45 50 ①Charging energy in Cin Charging energy[μJ] = 1 1 × Cin × (VUVLOH 2 ) = × 470[μF] × 5.2[V]2 = 6354[μJ] 2 2 ②Charging time in Cin (measured value) Charging time[s] = 41 [s] 1 2 ③Power generation capability Power generation capability[μW] = Charging energy[μJ] ÷ Charging time[s] = Power generation capability[μW] = 6354 [μJ] ÷ 41 [s] = 155 [μW] = 1 2 1 2 After the voltage of the Cout becomes the preset output voltage, more energy is charged into the Cin until the open circuit voltage of the solar cell. The power generation capability during the period is calculated. 12 CONFIDENTIAL AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N Figure 3-4 N O T E Block diagram with Amorphous silicon solar cell Light(1000[lx]) 35µW VIN Solar Cell 46mm×30mm 9 cells Vf=0.28V Vopen VUVLOH MB39C811 VVOUT Cin =470µF 0V VVOUT : Preset output voltage After the Charging time of Cin and Cout Amorphous Si solar cell 20 Amorphous Si solar cell 9 cells, Size: 46x30mm 8 12 41s 8 VIN 9 cells, Size: 46x30mm Preset output voltage = 3.3V Illuminance = 1000lx Cin = 470µF 7 Cout = 47µF open circuit voltage 6.4V Voltage [V] Voltage [V] Preset output voltage = 3.3V 18 Illuminance = 1000lx 16 Cin = 470µF Cout = 47µF 14 10 Cout =47µF 0V VUVLOH : UVLO release voltage Vopen : Combined open voltage Figure 3-5 VOUT=3.3V Buck DC/DC open circuit voltage 6.4V VIN 6 6 5.1V 5 4 VOUT 2 0 0 50 100 150 200 Time [s] 42s 250 300 4 40 142 s 60 80 100 120 Time [s] 140 160 ④Charging more energy in Cin Charging energy[μJ] = 1 × 80[%] × 470[μF] × (6.4[V]2 − 5.1[V]2 ) = 3513[μJ] 2 ⑤Charging time in Cin (measured value) Charging time [s] = 100 [s] 1 2 ⑥Power generation capability Power generation capability[μW] = Charging energy[μJ] ÷ Charging time [s] = Power generation capability[μW] = 3513[μJ] ÷ 100 [s] = 35[μW] = 1 2 1 2 The power generation capability is much smaller than that until the Cin become the preset output voltage. That is because of the characteristics of the solar cell. This solar cell acts as a current source until around 5V (see Figure 3-6). However, the current supply suddenly decrease after the voltage goes over 5V. July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 13 A P P L I C A T I O N Figure 3-6 N O T E Characteristic of amorphous silicon solar cell Amorphous Si characteristics 100 9 cells, Size: 46x30mm Illuminance = 1000lx Current [µA] 80 60 40 20 0 0 14 CONFIDENTIAL Vf of diode 0.28V 1 2 3 4 5 Voltage [V] 6 7 6.4V 8 AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N 3.3 N O T E Amorphous silicon solar cell in series (for MB39C811) Table 3-4 Generator Characteristics of 2 series Amorphous silicon solar cells Type Solar Size Vmax Imax [mm] [V] [mA] 13.8 --- Amorphous 46×30 Si (2 series) Figure 3-7 Light(1000[lx]) capability [µW] 1000[lx] 193 [µW] Block diagram with 2 series Amorphous silicon solar cells Light(1000[lx]) 193µW VIN Solar Cell Solar Cell 46mm×30mm 9 cells 46mm×30mm 9 cells VOUT=3.3V Buck DC/DC Vf=0.28V MB39C811 VUVLOH VVOUT Cin =470µF 0V 0V Cout =47µF VVOUT : Preset output voltage VUVLOH : UVLO release voltage Figure 3-8 Power generation condition Measured graph using amorphous silicon solar cells in series Amorphous Si solar cell 8 [2 series] 9 cells, Size: 46x30mm Voltage [V] Preset output voltage = 3.3V 7 Illuminance = 1000lx transfer of energy Cin = 470µF from Cin to Cout 6 Cout = 47µF 5 4 34s VIN 3.3V 3 2 1 33s VOUT 0 0 5 10 15 20 25 30 Time [s] 35 40 45 50 ①Charging energy in Cin Chargeing energy[μJ] = 1 1 × Cin × (VUVLOH 2 ) = × 470[μF] × 5.2[V]2 = 6354[μJ] 2 2 ②Charging time in Cin (measured value) Charging time [s] = 33 [s] 1 2 ③Power generation capability Power generation capability[μW] = Charging energy[μJ] ÷ Charging time[s] = Power generation capability[μW] = 6354 [μJ] ÷ 33 [s] = 193 [μW] = July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 1 2 1 2 15 A P P L I C A T I O N Figure 3-9 N O T E Measured graph using amorphous silicon solar cell in series Amorphous Si solar cell 20 [2 series] 9 cells, Size: 46x30mm Voltage [V] Preset output voltage = 3.3V 18 Illuminance = 1000lx 16 Cin = 470µF Cout = 47µF 14 12.8V 12 10 VIN 33s 8 6 VOUT 4 2 0 0 50 100 150 200 Time [s] 250 300 The more energy from a harvester can be stored on a capacitor because the energy in a capacitor is proportional to the square of the voltage. Energy[μJ] = 1 × 470[μF] × Voltage2 2 Figure 3-10 Energy vs input voltage in capacitor Energy vs Voltage in Cin 50 Cin = 470µF (maximum rating ≧ 12.8V) 38.5mJ Energy [mJ] 40 30 12.8V 6.4V 5.2V 20 9.6mJ 10 6.4mJ 0 0 16 CONFIDENTIAL 2 4 8 6 Voltage [V] 10 12 14 AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N 3.4 N O T E Piezo (for MB39C811) Table 3-5 Generator Piezo Type Polymer Characteristics of Piezo Size Vmax Imax [mm] [V] [mA] 80(Vpp) 80×30 Figure 3-11 Power generation condition capability [µW] 3Hz, --- 578 [µW] hand push Testing method using Piezo Hand push Piezo(8cm x 3cm) based plates that are flexible about 5 cm Figure 3-12 Measured graph using Piezo Piezo 20 Based plate that is flexible Voltage [V] Preset output voltage = 3.3V 18 About 3Hz by hand push 16 Cin = 470µF Cout = 47µF 14 12 10 VIN 8 11s 6 14s 4 VOUT 3.3V 2 0 0 10 20 30 Time [s] 40 50 60 ①Charging energy in Cin Energy for charging[μJ] = 1 1 1 × Cin × (VUVLOH 2 ) = × 470[μF] × 5.2[V]2 = 6354[μJ] 2 2 2 ②Charging time in Cin (measured value) Charging time[s] = 11 [s] 1 2 ③Power generation capability Power generation capability[μW] = Charging energy[μJ] ÷ Charging time[s] = Power generation capability[μW] = 6354[μJ] ÷ 11 [s] = 578 [μW] = July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 1 2 1 2 17 A P P L I C A T I O N Figure 3-13 N O T E Block diagram with Single crystal silicone solar cell -1- Hand push (3[Hz]) Piezo 80mm×30mm 578µW VIN Polymer VUVLOH 0V VUVLOH : UVLO release voltage 18 CONFIDENTIAL Buck DC/DC VOUT=3.3V MB39C811 Cin =470µF VVOUT 0V Cout =47µF VVOUT : Preset output voltage AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N 3.5 N O T E Single crystal silicon solar cell -1- (for MB39C831) Table 3-6 Generator Characteristics of single crystal silicone solar cell -1Size Vmax Imax [mm] [V] [mA] 50×50 0.5 500 Type Single Solar crystal Si Power generation condition capability [µW] 50000[lx] 233 [µW] (*1) *1: the value including the MB39C831’s consumption Figure 3-14 Measured graph using Single crystal silicone solar cell -1Single crystal Si solar cell 5 Vopen = 0.5V, Ishort = 500mA Voltage [V] Preset output voltage = 3.3V Illuminance = 50000lx 4 Cin = 10µF Cout = 470µF 11s 3.3V 3 VOUT 2 1 0 0 2 4 6 10 8 Time [s] 14 12 16 The Cin is excluded from the energy calculation because the input voltage (VDD) is not stable in the start-up and the stored energy is very small. ①Charging energy in Cout Chargeing energy[μJ] = 1 1 × Cout × (VOUT 2 ) = × 470[μF] × 3.3[V]2 = 2559[μJ] 2 2 ②Charging time in Cout (measured value) Time for charging[s] = 11 [s] 1 2 ③Power generation capability Power generation capability[μW] = Charging energy[μJ] ÷ Charging time [s] = Power generation capability[μW] = 2559 [μJ] ÷ 11 [s] = 233 [μW] = Figure 3-15 1 2 1 2 Block diagram with Single crystal silicone solar cell -1- Light(50000[lx]) VDD Single Crystal Si Solar Cell 50mm×50mm Vmax = 0.5V Imax = 500 mA VDD : VDD input voltage July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL Boost DC/DC MB39C831 VDD 0V Cin =10µF VOUT : VOUT=3.3V 233µW VOUT 0V Cout =470µF Preset output voltage 19 A P P L I C A T I O N 3.6 N O T E Single crystal silicon solar cell -2- (for MB39C831) Table 3-7 Generator Solar Characteristics of single crystal silicone solar cell -2Size Vmax Imax [mm] [V] [mA] 80×70 1.5 500 Type Single crystal Si Power generation condition capability [µW] 50000[lx] 1706 [µW] (*1) *1: the value including the MB39C831’s consumption Figure 3-16 Measured graph using Single crystal silicone solar cell -2Single crystal Si solar cell 5 Vopen = 1.5V, Ishort = 500mA Voltage [V] Preset output voltage = 3.3V Illuminance = 50000lx 4 Cin = 10µF Cout = 470µF VOUT 3 3.3V 1.5s 2 1 0 0 2 4 6 10 8 Time [s] 12 14 16 The Cin is excluded from the energy calculation because the input voltage (VDD) is not stable in the start-up and the stored energy is very small. ①Charging energy in Cout Chargeing energy[μJ] = 1 1 × Cout × (VOUT 2 ) = × 470[μF] × 3.3[V]2 = 2559[μJ] 2 2 ②Charging time in Cout (measured value) Time for charging[s] = 1.5 [s] 1 2 ③Power generation capability Power generation capability[μW] = Charging energy[μJ] ÷ Charging time [s] = Power generation capability[μW] = 2559 [μJ] ÷ 1.5 [s] = 1706 [μW] = Figure 3-17 1 2 1 2 Block diagram with single crystal silicone solar cell -2- Light(50000[lx]) VDD Single Crystal Si Solar Cell 80mm×70mm Vmax = 1.5V Imax = 500 mA VDD : VDD input voltage 20 CONFIDENTIAL VOUT=3.3V 1706µW Boost DC/DC MB39C831 VDD 0V Cin =10µF VOUT : VOUT 0V Cout =470µF Preset output voltage AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N 3.7 N O T E Peltier (for MB39C831) Peltier elements provide relatively large amount energy upon being given temperature difference. However, they do not supply high voltage. The peltier element shown in Table 3-8 supplies up to 0.352V. To meet the minimum start-up input voltage of MB39C831, use the peltier elements connected in series. Table 3-8 Generator Type Peltier --- Peltier --- Characteristics of Peltier Size Vmax Imax [mm] [V] [mA] 0.234 - 0.077 - 0.352 0.117 10×10 0.468 - 0.077 - (2 series) 0.704 0.117 10×10 Power generation condition capability [µW] ΔT=30℃ Larger than 22000 [µW] (*1) ΔT=30℃ Larger than 44000 [µW] (*1) *1: the value from a peltier’s datasheet Figure 3-18 Heat (ΔT=30℃) Block diagram with Peltier Heat (ΔT=30℃) 44000µW Peltier 10mm×10mm 0.234V to 0.352V Peltier 10mm×10mm VDD Boost DC/DC 0.468V to 0.704V MB39C831 VDD 0V VOUT=3.3V VOUT Cin =10µF 0V Cout =470µF Efficiency=70% VDD : VDD input voltage July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL VOUT : Preset output voltage 21 A P P L I C A T I O N N O T E AN405-00001-1v0-E Spansion Application Note Energy Calculation For Energy Harvesting APPLICATION NOTE July 2014 Rev. 1.0 Published Edited 22 CONFIDENTIAL Spansion Inc. Communications AN405-00001-1v0-E, July 18, 2014 A P P L I C A T I O N N O T E Colophon The products described in this document are designed, developed and manufactured as contemplated for general use, including without limitation, ordinary industrial use, general office use, personal use, and household use, but are not designed, developed and manufactured as contemplated (1) for any use that includes fatal risks or dangers that, unless extremely high safety is secured, could have a serious effect to the public, and could lead directly to death, personal injury, severe physical damage or other loss (i.e., nuclear reaction control in nuclear facility, aircraft flight control, air traffic control, mass transport control, medical life support system, missile launch control in weapon system), or (2) for any use where chance of failure is intolerable (i.e., submersible repeater and artificial satellite). Please note that Spansion will not be liable to you and/or any third party for any claims or damages arising in connection with above-mentioned uses of the products. Any semiconductor devices have an inherent chance of failure. You must protect against injury, damage or loss from such failures by incorporating safety design measures into your facility and equipment such as redundancy, fire protection, and prevention of over-current levels and other abnormal operating conditions. If any products described in this document represent goods or technologies subject to certain restrictions on export under the Foreign Exchange and Foreign Trade Law of Japan, the US Export Administration Regulations or the applicable laws of any other country, the prior authorization by the respective government entity will be required for export of those products. Trademarks and Notice The contents of this document are subject to change without notice. This document may contain information on a Spansion product under development by Spansion. Spansion reserves the right to change or discontinue work on any product without notice. The information in this document is provided as is without warranty or guarantee of any kind as to its accuracy, completeness, operability, fitness for particular purpose, merchantability, non-infringement of third-party rights, or any other warranty, express, implied, or statutory. Spansion assumes no liability for any damages of any kind arising out of the use of the information in this document. ® ® ® TM Copyright © 2014 Spansion All rights reserved. Spansion , the Spansion logo, MirrorBit , MirrorBit Eclipse , TM ORNAND and combinations thereof, are trademarks and registered trademarks of Spansion LLC in the United States and other countries. Other names used are for informational purposes only and may be trademarks of their respective owners. July 18, 2014, AN405-00001-1v0-E CONFIDENTIAL 23