Overview
The LM3642TLX-LT/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 is controlled via an I2C-compatible interface, allowing for precise adjustments of flash and torch current levels, flash timeout duration, and switch current limit. It also includes various protection features such as overvoltage protection, thermal shutdown, and LED fault detection.
Key Specifications
| Parameter | Test Conditions | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Input Voltage Range | 2.5 | 5.5 | V | ||
| Flash Current | VOUT = 4 V | 93 mA | 1.04 A / 1.5 A | 1.5 A | A |
| Torch Current | VOUT = 4 V | 24 mA (LT option) | 48.4 mA / 375 mA | 375 mA | mA |
| Switching Frequency | 4 MHz | ||||
| Operating Temperature Range | -40°C | 85°C | °C | ||
| Package Type | DSBGA (9-bump) | ||||
| Package Size | 1.69 mm × 1.64 mm |
Key Features
- High-efficiency operation: > 85% efficiency in Torch Mode (at 100 mA) and Flash Mode (at 1 A to 1.5 A)
- Accurate programmable flash LED current: 93 mA to 1.5 A, and torch LED current: 48.4 mA to 375 mA (24 mA to 187 mA for LT option)
- 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
- 400-kHz I2C-compatible interface for control and configuration
- Overvoltage protection, thermal shutdown, and LED fault detection
- Adjustable current limit and flash timeout duration
Applications
- Camera phone LED flash: The LM3642 is particularly suited for camera flash applications in mobile devices due to its high current capability and efficiency
Q & A
- What is the maximum current output of the LM3642? The LM3642 can deliver up to 1.5 A of current to a single high-powered LED.
- What is the input voltage range of the LM3642? The input voltage range is from 2.5 V to 5.5 V.
- How is the LM3642 controlled? The LM3642 is controlled via an I2C-compatible interface.
- What are the programmable current ranges for the LM3642? The flash LED current can be programmed from 93 mA to 1.5 A, and the torch LED current can be programmed from 48.4 mA to 375 mA (24 mA to 187 mA for the LT option).
- What protection features does the LM3642 include? The LM3642 includes overvoltage protection, thermal shutdown, and LED fault detection.
- What is the switching frequency of the LM3642? The switching frequency is 4 MHz.
- What is the operating temperature range of the LM3642? The operating temperature range is from -40°C to 85°C.
- What package type and size does the LM3642 come in? The LM3642 comes in a 9-bump DSBGA package with dimensions of 1.69 mm × 1.64 mm.
- What are some typical applications of the LM3642? The LM3642 is typically used in camera phone LED flash applications.
- How does the LM3642 handle high battery current conditions? The LM3642 has a synchronization input (TX/TORCH) that can reduce the flash LED current during high battery current conditions such as RF power amplifier events.
