- Dual high-side current sources
- Cathodic grounding allows for better heat dissipation and LED routing
- > 90% efficiency
- Ultra-small solution size: 2
- Four operating modes: torch, flash, LED indicator and voltage output
- Accurate and programmable LED current from 1.2A to 37.5 mA
- Programmable 4.5V or 5.0V fixed output voltage
- Hardware flash and flashlight enabled
- LED thermal sensing and current Scaleback
- Software-selectable input voltage monitor
- Programmable Flash timeout
- RF power amplifier dual synchronous input pulse events
- LED open and short circuit detection
- High level enable protects system hardware faults
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400kHz me 2 C-compatible interface
- 16 solder balls (1.7mm×1.7mm×0.6mm) miniature SMD
illustrate
The LM3554 is a 2MHz fixed frequency, current mode synchronous boost converter. The device is designed to operate as two 600mA (1.2A total) constant current high current white LED drivers, or as regulated 4.5V or 5V voltage sources.
Dual high-side current sources allow the LED cathode to be grounded. An adaptive regulation approach to ensure that efficiency is maintained and maximized at each LED current source regulated.
Its main functions include: an I 2 C-compatible interface for controlling LED current or desired output voltage, hardware flash enables direct flash pulse trigger input, dual TX input, forcing into low-current flare sync mode allows for Flash pulsed RF power amplifier events or other high-current conditions. In addition, the Aggressive High Hardware Enable (HWEN) input provides a hardware shutdown in the event of a system software failure.
Five protection features provided by the LM3554 include software-selectable input voltage monitor, an interface with an external temperature sensor, four selectable current limits to ensure battery current falls below a predetermined peak continuously, an overvoltage protection function, internal comparator limiting the output voltage on the LED open circuit and output short-circuit protection, limiting the output current when shorted to GND. In addition, the device provides indicators for various faults, including: a thermal fault flag indicating that the thermal threshold of the LED temperature has tripped, a flag indicating that the TX event has occurred, a flag indicating that the flash timeout counter has expired, a flag indicating that the device die temperature has reached the thermal shutdown threshold, and an open flag indicating or shorting the LED.
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