Overview
The LM3405A, specifically the LM3405AXMY/NOPB, is a 1.6-MHz, 1-A constant current buck LED driver designed by Texas Instruments. This device is engineered to provide a simple and high-efficiency solution for driving high-power LEDs. It features an internal compensation mechanism, which simplifies the design process and enhances performance. The LM3405A is suitable for a variety of LED lighting applications, offering user-accessible enable and PWM dimming controls, thermal shutdown, cycle-by-cycle current limit, and overcurrent protection.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Switching Frequency | 1.6 | MHz |
| Output Current | 1 | A |
| Switch ON Resistance (SOT) | 300 - 600 | mΩ |
| Switch ON Resistance (MSOP-PowerPAD) | 360 - 700 | mΩ |
| Switch Current Limit | 1.2 - 2.8 | A |
| Quiescent Current (Switching) | 1.8 - 2.8 | mA |
| Quiescent Current (Shutdown) | 0.3 | µA |
| Enable Threshold Voltage (Rising) | 1.8 | V |
| Enable Threshold Voltage (Falling) | 0.4 | V |
| EN/DIM Pin Current | 0.01 | µA |
| Switch Leakage Current | 0.1 | µA |
Key Features
- User-accessible EN/DIM pin for enabling and PWM dimming of LEDs.
- Internal compensation simplifies the design process.
- Thermal shutdown and overcurrent protection for enhanced reliability.
- Cycle-by-cycle current limit to prevent overcurrent conditions.
- High efficiency operation to minimize heat and maximize LED lifespan.
- Available in SOT (6-pin) and MSOP-PowerPAD (8-pin) packages.
Applications
The LM3405A is ideal for various LED lighting applications, including but not limited to:
- High-power LED lighting systems.
- Automotive LED lighting.
- General lighting solutions requiring high efficiency and reliability.
- Backlighting for displays and signage.
Q & A
- What is the switching frequency of the LM3405A?
The switching frequency of the LM3405A is 1.6 MHz. - What is the maximum output current of the LM3405A?
The maximum output current is 1 A. - What types of packages are available for the LM3405A?
The LM3405A is available in SOT (6-pin) and MSOP-PowerPAD (8-pin) packages. - Does the LM3405A support PWM dimming?
Yes, the LM3405A supports PWM dimming through the EN/DIM pin. - What are the key protection features of the LM3405A?
The key protection features include thermal shutdown, cycle-by-cycle current limit, and overcurrent protection. - What is the quiescent current in shutdown mode?
The quiescent current in shutdown mode is 0.3 µA. - What is the typical quiescent current during switching operation?
The typical quiescent current during switching operation is between 1.8 and 2.8 mA. - How does the LM3405A regulate the output current?
The LM3405A regulates the output current by switching the internal NMOS power switch at a constant frequency and variable duty cycle. - What is the purpose of the BOOST pin?
The BOOST pin is used to drive the NMOS output switch, with a bootstrap capacitor connected between the BOOST and SW pins. - What is the function of the FB pin?
The FB pin is the feedback pin, connected to the LED string cathode and an external resistor to ground to set the LED current.
