Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
AN210772 Energy Calculation for Energy Harvesting with S6AE101A, S6AE102A, and S6AE103A Author: Hiroyuki Takada Associated Part Family:S6AE101A, S6AE102A, S6AE103A Related Documents: S6AE101A, S6AE102A, S6AE103A Datasheets This application note describes system energy calculations for an energy harvesting system where the amount of energy from an energy harvester is very small. 1 Introduction Systems that are dependent on an energy harvesting solution must be designed for a low-power operation based on an energy budget calculation because the amount of energy from the energy harvester such as indoor solar cell is very small. 1.1 Energy Harvesting System S6AE101A/2A/3A is a power management IC (PMIC) for energy harvesting operated with super-compact solar cells. Figure 1 shows an example of an energy harvesting system with S6AE101A/2A/3A. Figure 1. Example of Energy Harvesting System with S6AE101A/2A/3A Enveronmental Energy (Light) S6AE101A/2A/3A VDD Harvester Block (Solar Cell) PMIC Block SW2 SW1 Control Block VOUT1 VSTORE1 CVSTORE1 Application Block MCU RF Sensor Because the energy from a harvester is limited, it should be stored in a capacitor (CVSTORE1). A large-value capacitor would take too much time to store the energy into the capacitor; this means that the system cannot be operated frequently. On the other hand, if the capacitor were too small, enough energy cannot be stored on the capacitor for the application block. Therefore, the sizing of the capacitor is very important. This PMIC has a power gating switch, SW1, for the application block. Once the VSTORE1 pin voltage reaches the VOUT maximum voltage (VVOUTH), the path between the VSTORE1 pin and the VOUT1 pin is connected by the SW1 until the VSTORE1 pin voltage reaches the VOUT minimum voltage (VVOUTL) (see Figure 2). This PMIC has a switch, SW2, for charging the capacitor efficiently. After starting up the internal circuit of the PMIC, the path between the VDD pin and the VSTORE1 pin is connected by the SW2. When the VSTORE1 pin voltage reaches the VVOUTH, the SW2 disconnects the path. When the VSTORE1 pin voltage reaches the input power reconnect voltage (VVOUTM), the SW2 reconnects the path (see Figure 2). For more information, see S6AE101A, S6AE102A, and S6AE103A datasheets. www.cypress.com Document No. 002-10772 Rev. *B 1 Energy Calculation for Energy Harvesting with S6AE101A, S6AE102A, and S6AE103A Figure 2. Relationship between SW1, SW2 and VSTORE1 Pin VVOUTH VVOUTM VVOUTL VSTORE1 VOUT1 VOUT1 Load off SW1 SW2 off on off on on Starting up 2 Energy Calculation for Energy Harvesting 2.1 Calculation of Energy Consumption Figure 3. Measurements of Voltage, Current, and Operation Time S6AE101A/2A/3A VDD Power Source PMIC Block Control Block SW2 SW1 IAPP_IN VOUT1 VSTORE1 CVSTORE1 A APP_IN V VAPP_IN Application Block MCU RF Sensor First of all, the voltage (VAPP_IN), the current (IAPP_IN), and the operation time (tAPP_IN) of APP_IN pin in the application block are measured (see Figure 3 and Figure 4). The energy consumption in the application is calculated from Equation 1. Equation 1 However, when checking the waveform of VAPP_IN and IAPP_IN in the Figure 4, the waveform is divided into three parts, (1), (2), and (3). Therefore, the energy consumptions of each part should be calculated, and then three energy consumptions are added together. In this example, the energy consumption for the application block is calculated as 233.4 µJ. www.cypress.com Document No. 002-10772 Rev. *B 2 Energy Calculation for Energy Harvesting with S6AE101A, S6AE102A, and S6AE103A Figure 4. Waveform of VAPP_IN, IAPP_IN, and tAPP_IN VVOUTH = 3.3 V, VVOUTM = 3.135 V, VVOUTL = 2.0 V V(1) ≈ 3.28 V (Average) V ≈ 3.15 V (Average) (2) V(3) ≈ 2.80 V (Average) VAPP_IN 1 V/div (1) (2) (3) (3) RF transmission I(3) ≈ 10 mA (1) MCU IAPP_IN 5 mA/div (2) MCU & Sensor I(2) ≈ 3 mA I(1) ≈ 1 mA 5 ms/div t(1) ≈ 5 ms t(2) ≈ 20 ms t(3) ≈ 1 ms tAPP_IN ≈ 26 ms 2.2 SW1 off SW2 on on off on Calculation of Capacitance Next, the capacitance is calculated based on the energy consumption of the application. Figure 5 shows the capacitor in the system. Figure 5. Capacitor in the System S6AE101A/2A/3A VDD Power Source PMIC Block SW2 SW1 VSTORE1 Control Block : Available Energy (EAVAILABLE) VVOUTH : VOUT maximum voltage VVOUTL : VOUT minimum voltage VOUT1 CVSTORE1 EAVAILABLE Application EAPP_IN = 233.4 µJ VVOUTH VVOUTL 0V The energy stored on a capacitor is calculated by Equation 2 (E: Energy [J], C: capacitance [F], V: Voltage [V]). Equation 2 Calculation of CVSTORE1 The VOUT maximum voltage (VVOUTH) and the VOUT minimum voltage (VVOUTL) of S6AE101A/2A/3A are set by changing the external resistances. As a premise, the recommended operating voltage range for the application block is set from 1.8 V to 3.6 V. Then, VVOUTH is set to 3.3 V and VVOUTL is set to 2.0 V within the range. The stored energy from VVOUTL to VVOUTH is the available energy for the application. (EAVAILABLE: Available energy, see Figure 5). EAVAILABLE should be larger than the EAPP_IN (233.4 µJ). (Equation 3 is derived from Equation 2) Equation 3 www.cypress.com Document No. 002-10772 Rev. *B 3 Energy Calculation for Energy Harvesting with S6AE101A, S6AE102A, and S6AE103A In this example, the capacitance of CVSTORE1 should be larger than 67.8 µF. Moreover, at least 100-µF or larger capacitor is required for this PMIC (see the recommended operating conditions in S6AE101A, S6AE102A, and S6AE103A datasheets). The capacitance is set to 100 µF in this example. Note: The calculated capacitance in this example is the ideal value. There is a wide difference between an actual capacitance and a capacitance described in a datasheet. Also, there is a potential for a decrease in a capacitance by DC bias characteristics and temperature characteristics. When selecting a capacitor, please check datasheets for each manufacturer and check the actual capacitances under actual use conditions. The type of capacitors and the characteristics for the energy harvesting are shown in Table 1. Ceramic capacitors with low leakage current are suitable for energy the harvesting. Table 1. Capacitor Characteristics Type of Capacitor Capacitance Range Benefit Drawback Low leakage current (nA), Ceramic capacitor 0.1 µF to 470 µF Small size, Small capacitance Low cost Aluminum electrolytic capacitor 0.1 µF to 1.5 F Tantalum electrolytic capacitor 33 nF to 6 mF Electric double-layer capacitor (e.g., Supercapacitor) 2.3 High capacitance, High leakage current (µA) Low cost Low leakage current (nA), High cost High capacitance Up to 50 F High leakage current (µA) Ultrahigh capacitance High cost Calculation of Charging Time The parameters for calculating charging time for the capacitor are shown in Figure 6. Figure 6. Calculating the Parameters for Charging Time Light Energy PSOLAR = 200 µW S6AE101A/2A/3A VDD Solar Cell PMIC Block SW1 : Available Energy (EAVAILABLE) : Initial Energy (EINITIAL) VOUT1 VSTORE1 PVSTORE1 CVSTORE1 = 100 µF Control Block IQIN1 = 250 nA or 280 nA (Consumption current 1) + SW2 VVOUTH = 3.3 V VVOUTL = 2.0 V 0V Application EAPP_IN = 233.4 µJ Repeat charge energy Initial charge energy This calculation assumes that the power from a solar cell (PSOLAR) is 200 µW. The charge power (PVSTORE1) to be supplied to the VSTORE1 pin capacitor (CVSTORE1) is the value PSOLAR minus the power consumption (VVOUTH × IQIN1) of the PMIC (Equation 4) Values of consumption current 1 (IQIN1) of S6AE101A/2A/3A are shown in Table 2. In this example, the value of S6AE101A is used. Equation 4 www.cypress.com Document No. 002-10772 Rev. *B 4 Energy Calculation for Energy Harvesting with S6AE101A, S6AE102A, and S6AE103A Table 2. Consumption Current 1 (IQIN1) Product Name Consumption Current 1 (IQIN1) S6AE101A 250nA S6AE102A 280nA S6AE103A Calculation of Initial Charging Time (tCHARGE) The capacitor is charged from 0 V to VVOUTH at the time of initial charging. The initial energy (EINITIAL) is calculated by Equation 2. Equation 5 is derived from Equation 1 (E: Energy [J], P: Power [W], and t: time [s]). Equation 6 for the charging time is derived from Equation 5. Equation 5 Equation 6 Calculation of Repeat Charging Time (tCHARGE_R) In this example, the initial charging time is 2.73 s, and the repeat charging time is 1.17 s. The repeat charging time is shorter than the initial one. 3 Summary This application note explored the basic calculation of energy, capacitance, and charging time for an energy harvesting application based on Cypress’s S6AE101A/2A/3A PMIC. The most important concept to be gained from this application note is to figure out a balance of charged energy with energy consumption. S6AE101A/2A/3A has a set of documentation such as other application notes, development tools, and online resources to assist you during your development process. Visit www.cypress.com/energy-harvesting to find out more. www.cypress.com Document No. 002-10772 Rev. *B 5 Energy Calculation for Energy Harvesting with S6AE101A, S6AE102A, and S6AE103A Document History Document Title: AN210772 - Energy Calculation for Energy Harvesting with S6AE101A, S6AE102A, and S6AE103A Document Number: 002-10772 Revision ECN ** 5099308 Orig. of Change Submission Date HIXT 02/17/2016 Description of Change New application note Added the following sentences on page 4. *A 5273891 HIXT 05/17/2016 Moreover, at least 100-µF or larger capacitor is required for this PMIC (see the recommended operating conditions in S6AE101A, S6AE102A, and S6AE103A datasheets). The capacitance is set to 100 µF in this example. Corrected typo error *B 5690448 www.cypress.com AESATMP8 04/10/2017 Updated logo, and Copyright. Document No. 002-10772 Rev. *B 6 Energy Calculation for Energy Harvesting with S6AE101A, S6AE102A, and S6AE103A Worldwide Sales and Design Support Cypress maintains a worldwide network of offices, solution centers, manufacturer’s representatives, and distributors. To find the office closest to you, visit us at Cypress Locations. Products ® ® PSoC® Solutions ARM Cortex Microcontrollers cypress.com/arm Automotive cypress.com/automotive Clocks & Buffers cypress.com/clocks Interface cypress.com/interface Internet of Things cypress.com/iot Memory cypress.com/memory Microcontrollers cypress.com/mcu PSoC cypress.com/psoc Power Management ICs cypress.com/pmic Touch Sensing cypress.com/touch USB Controllers cypress.com/usb Wireless Connectivity cypress.com/wireless PSoC 1 | PSoC 3 | PSoC 4 | PSoC 5LP | PSoC 6 Cypress Developer Community Forums | WICED IOT Forums | Projects | Videos | Blogs | Training | Components Technical Support cypress.com/support All other trademarks or registered trademarks referenced herein are the property of their respective owners. Cypress Semiconductor 198 Champion Court San Jose, CA 95134-1709 © Cypress Semiconductor Corporation, 2016-2017. This document is the property of Cypress Semiconductor Corporation and its subsidiaries, including Spansion LLC (“Cypress”). This document, including any software or firmware included or referenced in this document (“Software”), is owned by Cypress under the intellectual property laws and treaties of the United States and other countries worldwide. Cypress reserves all rights under such laws and treaties and does not, except as specifically stated in this paragraph, grant any license under its patents, copyrights, trademarks, or other intellectual property rights. If the Software is not accompanied by a license agreement and you do not otherwise have a written agreement with Cypress governing the use of the Software, then Cypress hereby grants you a personal, non-exclusive, nontransferable license (without the right to sublicense) (1) under its copyright rights in the Software (a) for Software provided in source code form, to modify and reproduce the Software solely for use with Cypress hardware products, only internally within your organization, and (b) to distribute the Software in binary code form externally to end users (either directly or indirectly through resellers and distributors), solely for use on Cypress hardware product units, and (2) under those claims of Cypress’s patents that are infringed by the Software (as provided by Cypress, unmodified) to make, use, distribute, and import the Software solely for use with Cypress hardware products. Any other use, reproduction, modification, translation, or compilation of the Software is prohibited. TO THE EXTENT PERMITTED BY APPLICABLE LAW, CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS DOCUMENT OR ANY SOFTWARE OR ACCOMPANYING HARDWARE, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. To the extent permitted by applicable law, Cypress reserves the right to make changes to this document without further notice. Cypress does not assume any liability arising out of the application or use of any product or circuit described in this document. Any information provided in this document, including any sample design information or programming code, is provided only for reference purposes. It is the responsibility of the user of this document to properly design, program, and test the functionality and safety of any application made of this information and any resulting product. Cypress products are not designed, intended, or authorized for use as critical components in systems designed or intended for the operation of weapons, weapons systems, nuclear installations, life-support devices or systems, other medical devices or systems (including resuscitation equipment and surgical implants), pollution control or hazardous substances management, or other uses where the failure of the device or system could cause personal injury, death, or property damage (“Unintended Uses”). A critical component is any component of a device or system whose failure to perform can be reasonably expected to cause the failure of the device or system, or to affect its safety or effectiveness. Cypress is not liable, in whole or in part, and you shall and hereby do release Cypress from any claim, damage, or other liability arising from or related to all Unintended Uses of Cypress products. You shall indemnify and hold Cypress harmless from and against all claims, costs, damages, and other liabilities, including claims for personal injury or death, arising from or related to any Unintended Uses of Cypress products. Cypress, the Cypress logo, Spansion, the Spansion logo, and combinations thereof, WICED, PSoC, CapSense, EZ-USB, F-RAM, and Traveo are trademarks or registered trademarks of Cypress in the United States and other countries. For a more complete list of Cypress trademarks, visit cypress.com. Other names and brands may be claimed as property of their respective owners. www.cypress.com Document No. 002-10772 Rev. *B 7