The system automatically switches ON the lamps at dusk and switches them OFF at dawn. Although the following simple automatic solar LED garden light circuit looks simple, it includes a few interesting features which makes this design extremely adaptable, versatile, safe, efficient and long lasting. The mains features are listed below:
This product has Solar LED driver functions. The manufacturers of this product is Shiningic. Image The solar lawn lamp mainly uses the energy of the solar cell to work.
The circuit pulses the small inductor to step up the voltage to drive the LED in a similar way as a Joule Thief circuit. The use of a single AAA NiCd rechargeable cell keeps the cost down. Which also means the solar panel can be a cheaper low voltage version.
Looking from the outside, they generally consist of a small solar panel to charge a battery and a high brightness white LED. A typical most inexpensive example, as shown in figure 1, costs as little as $1.00 but maybe up to $2.00 each. Figure 1, Typical solar LED light
They use the internal ESD diode between the CE ( chip enable ) input and ground for charging the NiCd cell from the solar panel, but also use the voltage ( or lack thereof ) from the solar panel to detect when it is dark enough to turn the LED on. The CE input includes a small pull-up current. I measured about 30 uA with 1.25 volts on VDD .
The following image shows a high power automatic garden porch light circuit using a 12V 7 Ah battery. The LEDs used are high power 1 watt LED each. Since 9 LEDs are used the total power output becomes 9 watt. Please remember to connect a Diode between R1 and the battery positive.