The RT4505 is a maximum 4MHz frequency synchronous Boost converter plus a 1.5A constant current driver for a high current white LED. The high-side current source allows for grounded cathode LED operation providing flash current up to 1.5A. An adaptive regulation method ensures the current source remains in regulation and maximizes efficiency.

The RT4505 is controlled via an I2C-compatible interface. Features include a hardware flash enable (STROBE) allowing a logic input to trigger the flash pulse as well as a TX input which forces the flash pulse into a low current, allowing for synchronization to RF power amplifier events or other high-current conditions.

The maximum 4MHz switching frequency, over-voltage protection and adjustable current limit settings allow the use of tiny, low-profile inductors and ceramic capacitors. The device is available in a small WL-CSP-9B 1.3x1.37 (BSC) package, and operates within the -40°C to 85°C temperature range.


  • Camera Phone LED Flash
Status Active
Vin (min) (V) 2.5
Vin (max) (V) 5.5
SW Freq (typ) (kHz) 4000
Number of LEDs (max) (pcs) 1
Iout (max)/channel (mA) 1500
Iq (typ) (mA) 0.45
Dimming Control I2C
Topology Boost + Current Source
Features OVP;UVP
Package Type WL-CSP1.3x1.37-9
  • 1.5A High-Side Current Source for Single LED
  • Up to 90% Efficiency in Torch Mode and Flash Mode
  • Typical 5% LED Current Accuracy
  • Typical 7.5% Timeout Accuracy
  • Programmable Flash LED Current from 93.74mA to 1.5A
  • Programmable Torch LED Currents from 49.6mA to 375mA
  • Built-In Soft-Start Operation for Battery Protection
  • Built-In Over-Voltage Protection, Over-Current Protection, and Over-Temperature Protection
  • VIN Flash Monitor Optimization
  • Hardware Strobe Enable
  • Synchronization Input for RF Power Amplifier Pulse Events
  • 400KHz I2C Control Interface
  • 9-Ball WL-CSP Package
  • RoHS Compliant and Halogen Free
TitleLast UpdateDownload
1.5A Flash LED Driver with High-Side Current Source2014/05/30