peculiarity
Dual high-side current sources allow cathode-grounded LED operation
Accurate and programmable LED current from 28.125 mA to 1.8A
Optimized flash current at low battery voltages
Independent LED current source is programmable
Efficiency> 90%
Dimensions of ultra-small (total) solutions:Four operating modes: torch, flash, privacy indicator, and message indicator
The 4-bit ADC monitors the V-LEDs
Battery voltage sensing and current reduction
LED thermal sensing and current scale back
Hardware Flash and torch enabled
Dual synchronous input RF power amplifier pulse events
LED and output disconnect functions during shutdown
Open and short LED detection
I 2 C compatible interface at 400 kHz
Active low hardware reset
16 solder balls (1.97mm x 1.97mm x 0.6mm) micro SMD
illustrate
The LM3559 is a 2MHz fixed frequency synchronous boost converter with two 900 mA constant high current white LEDs as a current driver. Dual high-side current sources allow cathode-grounded LED operation and provide flash current of 1.8A, which can be paralleled. The adaptive regulation method ensures that each LED still regulates the current to maximize efficiency.
The LM3559 is a 2C compatible interface through my control. Features include: a built-in 4-bit ADC to monitor the voltage of the LED, independent hardware flash LED current control capable of allowing a logic input to trigger flash pulses, dual Tx inputs to force into a low-current torch-permitting mode for flash pulses in the event of an RF power amplifier or other high-current conditions, a comprehensive comparison designed to monitor NTC thermistors and provide LED current interrupts, and an input voltage monitor to monitor battery low battery conditions. Synchronously monitors battery voltage and optimizes flash current at low battery voltage conditions with flash current synchronization. In addition, the active high HWEN input provides a hardware shutdown in the event of a system software failure.
The 2MHz switching frequency, overvoltage protection, and adjustable current limit allow the use of tiny, low profile (1μH or 2.2μH) inductors and ceramic capacitors (10μF). The device can be packaged in an ultra-small 16 solder ball (1.97 mm x 1.97 mm x 0.6 mm) micro SMD package and operates over a temperature range of -40°C to +85°C.
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Photo phone LED flashing
White LED bias