The NUD4001/4011 are two-output configurable constant current sources from ON Semiconductor, designed for use with SMD LEDs of sizes 3528 and 5050. The NUD4001 is ideal for driving 0.5-1W LEDs, while the NUD4011 is suitable for low-power LEDs ranging from 20mA to 60mA. These devices are widely used in LED lighting applications due to their efficiency and ease of integration.
The NUD4001 comes in an S0-8 package and features a wide input voltage range, up to 30V, with a maximum output current of 500mA. It allows for simple drive circuits that save PCB space, making it an excellent choice for compact designs. Key parameters include a maximum output voltage of 28V, an antistatic voltage rating of 1000V, and an operating temperature range from -40°C to +125°C. The device also has a thermal resistance of 110°C/W and a power consumption of up to 1.13W.
The pin configuration of the NUD4001 is as follows:
| Pin | Symbol | Function |
|-----|--------|----------|
| 1 | Vin | Power input |
| 2 | Boost | Can drive an external transistor; can be left unconnected if not used |
| 3 | Rext | Resistor connected to Vin to set output current |
| 4 | GND | Ground |
| 5–8 | Lout | Anodes of the LEDs connected in parallel |
The relationship between the output current (Iout) and the external resistor (Rext) is shown in the figure. At a junction temperature (Tj) of 25°C, the formula Rext = Vsense / ILED can be used. For example, if ILED = 350mA and Vsense = 0.7V, then Rext = 2.0Ω. However, the output current decreases as Tj increases, which is illustrated in the characteristic curves.
The maximum power consumption of the NUD4001 is 1.13W at TA = 25°C. If the ambient temperature rises, the allowable power consumption must decrease, which may require reducing the output current or using multiple devices in parallel.
An example application involves driving three 1W LEDs in series with a 12V battery. The steps include calculating Rext, determining the LED voltage (VLED), and computing the power dissipation (PD). The total power (PD_total) should be less than the maximum allowed to ensure safe operation.
The NUD4001 is also used in various applications such as automotive brake lights, headlights, and PWM-controlled brightness systems. For high-voltage inputs, the NUD4011 is preferred due to its higher input and output voltage capabilities, though it has a lower maximum output current and reduced ESD protection.
The NUD4011 operates with a maximum input voltage of 200V and an output current of up to 70mA. Its pin 4 is labeled as PWM instead of GND, which changes the application circuit depending on whether the output voltage is above or below 48V. This makes it suitable for AC-powered LED systems, where full-wave rectification is used to supply power.
In summary, both the NUD4001 and NUD4011 are versatile constant current drivers for LED applications, each suited for different voltage and current requirements. Understanding their characteristics and proper usage ensures optimal performance and longevity in various lighting designs.
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