| Input voltage (type) | DC/DC |
| Topology | Boost, Current Mode |
| Vin (Min) (V) | 2.7 |
| Vin (Max) (V) | 5.5 |
| Iout (Max) (A) | 1.2 |
| Iq (Typ) (mA) | 0.63 |
| Features | I2C Control |
| Operating temperature range (C) | -30 to 85 |
| Dimming method | Analog, PWM |
- Input Voltage: 2.5 V to 5.5 V
- Programmable 4.5-V or 5-V Constant Output Voltage
- Dual High-Side Current Sources
- Grounded Cathode Allowing for Better Heat Sinking and LED Routing
- > 90% Efficiency
- Ultra-Small Solution Size: < 23 mm2
- Four Operating Modes: Torch, Flash, LED Indicator, and Voltage Output
- Accurate and Programmable LED Current from 37.5 mA to 1.2 A
- Hardware Flash and Torch Enable
- LED Thermal Sensing and Current Scaleback
- Software Selectable Input Voltage Monitor
- Programmable Flash Timeout
- Dual Synchronization Inputs for RF Power-Amplifier Pulse Events
- Open and Short LED Detection
- Active High Hardware Enable for Protection Against System Faults
- 400-kHz I2C-Compatible Interface
The LM3554 is a 2-MHz fixed-frequency, current-mode synchronous boost converter. The device is designed to operate as a dual 600-mA (1.2 A total) constant-current driver for high-current white LEDs, or as a regulated 4.5-V or 5-V voltage source.
The main features include: an I2C-compatible interface for controlling the LED current or the desired output voltage, a hardware flash enable input for direct triggering of the flash pulse, and dual TX inputs which force the flash pulse into a low-current torch mode allowing for synchronization to RF power amplifier events or other high-current conditions. Additionally, an active high hardware enable (HWEN) input provides a hardware shutdown during system software failures.
Five protection features are available within the LM3554 including a software selectable input voltage monitor, an internal comparator for interfacing with an external temperature sensor, four selectable current limits to ensure the battery current is kept below a predetermined peak level, an overvoltage protection feature to limit the output voltage during LED open circuits, and an output short circuit protection which limits the output current during shorts to GND.
For all available packages, see the orderable addendum at the end of the data sheet.
