Build Your Solar Lamp: PR4403 Circuit Diagram

Description

The PR4403 represents a significant upgrade of the PR4402 40mA LED driver. It incorporates an additional input, LS, which can be set low to activate the LED. This simplifies the construction of automated LED lamps utilizing a rechargeable battery and a photovoltaic module. The LS input is directly connected to the photovoltaic module, enabling the module to function as a light sensor concurrently with battery charging via a diode. When darkness prevails, the voltage across the photovoltaic module diminishes; consequently, the PR4403 switches on when this voltage falls below a predetermined level. Conversely, during daylight hours, the battery is replenished, and the driver consumes only 100µA.

Circuit diagram:

During nighttime, the energy stored within the battery is channeled into the LED. Unlike conventional designs, this circuit can operate effectively with a single 1.2 V cell. The PR4403 is packaged in an SO-8 format with a lead pitch of 1.27 mm. Other key components include a 1N4148 diode (or a Schottky 1N5819) and a 4.7µH inductor. Pin 2 serves as the LS enable input, and it is connected directly to the photovoltaic module. As detailed in the datasheet, a series resistor (typically 1.2 M) can be connected at this point to further modify the effective threshold voltage, resulting in the LED illuminating slightly sooner as dusk approaches before complete darkness has settled in. Pins 3 and 6 of the device are connected together and collectively form the output of the circuit.

More about components

The PR4403 utilizes a sophisticated integrated circuit (IC) for precise LED current control. This IC, a digital light sensor driver, manages the flow of electricity to the LED, ensuring consistent brightness and preventing damage due to overcurrent. It is characterized by its low quiescent current consumption (100µA), contributing to energy efficiency. The IC’s digital input allows for adaptable control of the LED’s behaviour based on external sensor readings. This capability expands the system's functionality beyond a simple on-off switch, opening opportunities for automated lighting solutions based on ambient light conditions. The IC’s digital architecture allows for precise regulation of the LED’s current, ensuring consistent brightness and preventing damage due to overcurrent. It is characterized by its low quiescent current consumption (100µA), contributing to energy efficiency. The IC’s digital input allows for adaptable control of the LED’s behaviour based on external sensor readings.