Overview
The LM3642TLX/NOPB, produced by Texas Instruments, is a high-power white LED flash driver designed to deliver up to 1.5 A of current to a single high-powered LED. This device integrates a 4-MHz constant frequency-synchronous current-mode PWM boost converter and a single high-side current source. It operates over a 2.5-V to 5.5-V input voltage range, ensuring efficient and regulated LED current. The LM3642 features advanced control via an I2C-compatible interface, allowing for precise adjustment of flash and torch current levels, flash timeout duration, and switch current limit. It also includes various protection mechanisms such as overvoltage protection, current limit, undervoltage lockout, and thermal shutdown, making it a robust solution for LED flash applications.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Input Voltage Range | 2.5 | 5.5 | V | |
| Flash Current | 1.04 A (1 A flash) | 1.5 A (1.5 A flash) | 1.56 A (1.5 A flash) | A |
| Torch Current | 24 mA (LM3642-LT) | 48.4 mA | 375 mA | mA |
| Switching Frequency | 4 MHz | Hz | ||
| Operating Temperature Range | -40°C | 85°C | °C | |
| Package Type | DSBGA (9) | |||
| Body Size (Max) | 1.69 mm × 1.64 mm | mm |
Key Features
- High-efficiency boost converter with up to 85% efficiency in Torch Mode.
- Accurate programmable torch LED currents: 24 mA to 187 mA (LT option) and 48.4 mA to 375 mA.
- Small solution size: less than 20 mm².
- Soft-start operation for battery protection.
- Hardware strobe enable and synchronization input for RF power amplifier pulse events.
- Input voltage flash monitor optimization.
- 400-kHz I2C-compatible interface for control and monitoring.
- Overvoltage protection, current limit, undervoltage lockout, and thermal shutdown for robust operation.
- Support for Pass Mode and Boost Mode to maintain regulation.
Applications
- Camera phone LED flash.
- Other mobile device LED flash applications.
- General high-power LED lighting solutions requiring precise current control.
Q & A
- What is the maximum flash current of the LM3642?
The LM3642 can deliver up to 1.5 A of flash current.
- What is the input voltage range of the LM3642?
The input voltage range is from 2.5 V to 5.5 V.
- How does the LM3642 control the LED current?
The LM3642 controls the LED current via an I2C-compatible interface, allowing for precise adjustment of flash and torch current levels.
- What protection mechanisms does the LM3642 include?
The LM3642 includes overvoltage protection, current limit, undervoltage lockout, and thermal shutdown.
- What is the switching frequency of the LM3642?
The switching frequency is 4 MHz.
- How does the LM3642 handle high battery current conditions?
The LM3642 has a TX/TORCH input that allows synchronization with RF power amplifier events, reducing the flash LED current during high battery current conditions.
- What is the operating temperature range of the LM3642?
The operating temperature range is from -40°C to 85°C.
- What package type is the LM3642 available in?
The LM3642 is available in a 9-bump DSBGA package.
- How does the LM3642 protect against thermal issues?
The LM3642 has a thermal shutdown feature that shuts down the device if the die temperature reaches 150°C.
- What is the purpose of the Input Voltage Flash Monitor (IVFM) in the LM3642?
The IVFM adjusts the flash current based on the input voltage level, preventing excessive current during start-up.
