LEDs are among a few components that should be powered from current sources, where the current is stabilised, rather than the voltage. This stems from the nature of these components: each LED has its individual forward voltage value. In theory, you could select a suitable resistor to ensure optimal operating conditions for an LED, but in the case of multiple LEDs you would have to repeat the process for each one, which would mean the need to simplify certain aspects of the circuit design. This, in turn, would result in variations in brightness (even a slight disparity in current intensity yields noticeable effects). Moreover, the situation is further complicated by the influence of temperature.
The solution to these problems is to use current regulators, which help mitigate the effects of factors such as supply voltage, LED voltage and the temperature coefficient. Thanks to the regulators, you can achieve a stable current flow even if the factors mentioned above vary over relatively wide ranges.
StarChips specialises in integrated circuits for current regulators, which, after being fitted with additional features, are offered as LED drivers. The main operational element of such a component is an advanced current regulator enhanced with thermal protection, a startup current limiter (known as soft start) and light intensity regulation through PWM signal generation. The circuits described here are suitable for a wide range of supply voltages, while the output current value is adjustable, and it can be set by connecting several external components.
More advanced circuits, in addition to multiplied current drivers (up to 16 channels), have additional gate and logic circuits, shift registers, and other structures that allow for lighting control using a supervisory unit, such as a microcontroller. Such circuits are a great choice for various applications and simplify the design of LED displays, informational boards, etc.
| Characteristics | |
|---|---|
| Type of integrated circuit | driver |
| Kind of integrated circuit | LED driver |
| Output current* | from 5…30 mA up to 1.5 A |
| Number of channels* | 1…16 |
| Mounting method | SMD |
| Operating voltage | from 3…5.5 V up to 5...33 V |
* depending on the model
| Symbol | Number of channels | Body | Output current [mA] |
Operating voltage [V] |
|---|---|---|---|---|
| SCT2004CSOG | 4 | SOP8 | 20…320 | 4.5…5.5 |
| SCT2024CSOG | 16 | SOP24 | 5…30 | 3…5.5 |
| SCT2026CSOG | 16 | SOP24 | 5…60 | 4.5…5.5 |
| SCT2026CSTG | 16 | SSOP24-1.0 | 5…60 | 4.5…5.5 |
| SCT2932J | 1 | SOT23-5 | 1500 | 5…33 |
| SCT2001ASIG | 3 | SOT23-6 | 10…45 | 5…15 |
| SCT2024CSSG | 16 | SSOP24 | 5…30 | 3…5.5 |
| SCT2026CSSG | 16 | SSOP24 | 5…60 | 4.5…5.5 |
| SCT2110CSSG | 8 | SSOP16 | 5…160 | 4.5…5.5 |
| SCT2167CSSG | 8 | SSOP16 | 5…45 | 3..5.5 |
