I’m looking to make a DIY solar powered soap dispenser.
The logical steps would be as follows:
- Solar panel charges supercapacitor via ADP5090 chip
- Proximity sensor wakes up from sleep mode and is activated
- MCU turns on and sends a command to the motor to turn on
- Motor or motor pump is turned on and dispenses soap
- Motor turns off
- MCU goes back into deep sleep
- ADP5090 recharges supercapacitor if need be
I found these awesome solar to dc regulator reference designs on digikey’s site:
This is what I’m particularly interested in:
ADP 5090 solar-to-dc-regulator
page 6-8 in the attachment below contains schematic and BOM for parts.
The solar panel and capacitor they were referring to in the BOM datasheet:
ADP5090Data SheetRev. C | Page 18 of 21 TYPICAL APPLICATION CIRCUITSFigure 33. ADP5090 Based Energy Harvester Wireless Sensor Application with PV Cell as the Harvesting Energy Source (Trony 0.7 V, 60 μA, Alta Devices 0.72 V, 42 μA, Gcell 1.1 V, 100 μA), Shoei Electronics Polyacene Coin Type Capacitor PAS409HR as the Harvested Energy Storage, and Panasonic Primary Li-Ion Coin Cell CR2032 as the Backup Battery
I didn’t find the brand on Digikey but did find another they mentioned.
This brand claims 25% efficiency!!
This is the proximity sensor I was considering:
semtech-corporation SX9310ICSTRT proximity sensor
Ultra Low Power Consumption
Active Mode: 70 uA
Doze Mode: 8 uA
Sleep Mode: 2.5 uA
2.7 – 5.5V Core Supply (VDD)
1.65 – 2V Host Interface Supply (SVDD)
1.65 – 5.5V Compliant Host Interface (VPULL)
These are the relatively low cost motors I’m considering to use:
Rated voltage: DC 3V
No-load current: 20mA
DC Voltage: 3-6V (Title claims it can work at 2.5V)
Working current: 130-220mA
I want to use the lowest power MCU possible.
Right now I’m consider the same MCU from the Nano 33 IoT
It seems to have a low micro current usage per Mhz and low current usage in sleep mode.
Given that the motors have a near 3 volt operating range.
Would it be better to use the following components for the ADP5090 chip that are rated at or near 3.3 volts to minimize power losses and efficiency losses?:
Solar panel, powered by indoor bathroom lights, or if it’s daytime then light coming in thru windows
Current @ Pmpp 55.1mA
Voltage @ Pmpp 3.35V
IC REG LINEAR 3.3V 150MA 8VDFN
Current - Quiescent (Iq) 50nA
or (depending on current usage of motor to get it to start may need larger current output)
Linear Voltage Regulator IC 1 Output 500mA 6-TDFN (1.2x1.2)
Current - Quiescent (Iq) 55µA
These capacitors look like a lot better power options than the ones mentioned for ADP5090:
More expensive but less farads capacity but rated for 3.3V
330 mF, 3.3V
I’m not too familiar with capacitance leakage but I think I read about it somewhere.
Also found this site via the forum for potential knowledge about the subject:
I’ve attached the sensor and ADP5090 chip datasheets for reference in addition to the links provided above.
ADP5090-2-EVALZ_UG-782.pdf (452 KB)
SX9310_datasheet_Rev2_STD_200115.pdf (1.21 MB)