SCT2024 integrated circuit is a serial-parallel interface for LEDs with the programming and the limiting of the current on outputs in between 5 and 45mA. It makes an ideal option for commanding the displays with common anode with microcontroller. So the led driver is our discussion topic for today.
Usually, the LEDs are powered through resistors that reduce the value of the current beneath the limit supported by the LED. A better solution would be to use a generator of constant current as it allows you to control the luminous intensity of the LEDs with only one resistor.
A direct consequence of this benefit is the control over the brightness of the display by day and by night. We all know that the day light makes the LEDs less visible while at night their lighting can actually be upsetting. The good news is that you only need a simple circuit or even only one photoresistor.
When we work with multiple LEDs, the limiting resistors are rather bulky and the PCB will be more voluminous. However, the power voltage of the LEDs must be limited to 4 volts (3 of which are on the LED). For this purpose, you need to provide 5 volts through one or two rectifier diodes.
Another benefit would be the possibility of serial cascade on no matter how many levels, just as it shows from the application circuit.
From the catalog sheet I took the pins’ configuration and the application circuit:
This is the pins’ disposals on our integrated circuit.
The SCT2024 application circuits from the catalog sheet
The three options of package are: CSSG, CSTG and CSOG. The combination CSSG – SSOP24 is the smallest and it allows you to create working modules from a microcontroller and a LED display of smaller dimensions.
I’ve briefly presented you this integrated circuit because I’ve conceived a module with microcontroller from an ATMega8 central unit, a RFM01 wireless module as input interface and a SCT2024 x2 plus a double display with 7 segments and a dotx 2 as output interface. This module can be used for different practical applications such as: electronic thermometer, frequency meter, voltmeter, ampermeter etc, which I will present to you in the following posts. The PCB for this module has already been presented in here.
This is the smallest assembly you can get for this project.
These are the pins of our integrated circuit seen directly on the PCB
The brain behind this project – our command module with ATMega 8, RFM01 and, of course, SCT2024