Overview
The LM3405XMK/NOPB is a 1.6-MHz, 1-A constant current buck regulator designed by Texas Instruments for powering high-power LEDs. This device offers a simple and high-efficiency solution for LED driver applications. It operates with a preset switching frequency of 1.6 MHz, allowing the use of small surface mount capacitors and inductors, which minimizes the board space required. The LM3405 is internally compensated and uses current-mode control, making it easy to use and ensuring predictable, high-performance regulation over a wide range of operating conditions.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Input Voltage, VIN | 3 | 15 | V | |
| Output Current, IF | 1 | A | ||
| Switching Frequency | 1.6 | MHz | ||
| EN/DIM Voltage | 0 | VIN + 0.3 | V | |
| Boost to SW Voltage | 2.5 | 5.5 | V | |
| Junction Temperature, TJ | -40 | 125 | °C | |
| Shutdown Current at VIN = 5 V | 40 | nA | ||
| Switch Leakage at VIN = 15 V | 0.1 | µA | ||
| Thermal Resistance, θJA | 182.9 | °C/W |
Key Features
- VIN operating range of 3 V to 15 V
- Drives up to 5 high-brightness LEDs in series at 1 A
- Thin SOT-23-THN (DDC) package
- 1.6-MHz switching frequency
- EN/DIM input for enabling and PWM dimming of LEDs
- 300-mΩ NMOS switch
- Internally compensated current-mode control
- Cycle-by-cycle current limit
- Input voltage UVLO (Under Voltage Lock Out)
- Overcurrent protection
- Thermal shutdown
- Low shutdown current of 40 nA at VIN = 5 V
Applications
- LED drivers
- Constant current sources
- Industrial lighting
- LED flashlights
Q & A
- What is the input voltage range of the LM3405?
The input voltage range of the LM3405 is from 3 V to 15 V.
- How many high-brightness LEDs can the LM3405 drive in series?
The LM3405 can drive up to 5 high-brightness LEDs in series at 1 A.
- What is the switching frequency of the LM3405?
The switching frequency of the LM3405 is 1.6 MHz.
- What is the purpose of the EN/DIM pin on the LM3405?
The EN/DIM pin is used for enabling and PWM dimming of LEDs.
- What is the typical shutdown current of the LM3405 at VIN = 5 V?
The typical shutdown current is 40 nA at VIN = 5 V.
- Does the LM3405 have overcurrent protection?
Yes, the LM3405 includes overcurrent protection.
- How is the LED current set in the LM3405?
The LED current is set by an external resistor connected between the FB pin and ground, using the equation IF = VFB / R1.
- What is the thermal shutdown feature of the LM3405?
The LM3405 has a thermal shutdown feature to protect the device from overheating.
- What package type is the LM3405 available in?
The LM3405 is available in a SOT-23-THN (DDC) package.
- What is the junction temperature range for the LM3405?
The junction temperature range for the LM3405 is from -40°C to 125°C.
