LM3509

• Integrated OLED Display Power Supply and LED Driver
• Drives up to 10 LED’s at 30mA
• Drives up to 5 LED’s at 20mA and Delivers up to 21V at 40mA
• Over 90% Efficient
• 32 Exponential Dimming Steps
• 0.15% Accurate Current Matching Between Strings
• Internal Soft-Start Limits Inrush Current
• True Shutdown Isolation for LED’s
• Wide 2.7V to 5.5V Input Voltage Range
• 21V Over-Voltage Protection
• 1.27MHz Fixed Frequency Operation
• Low Profile 10-Pin WSON Package (3mm x 3mm x 0.8mm)
• General Purpose I/O
• Active Low Hardware Reset

All trademarks are the property of their respective owners.

The LM3509 current mode boost converter offers two separate outputs. The first output (MAIN) is a constant current sink for driving series white LED’s. The second output (SUB/FB) is configurable as a constant current sink for series white LED bias, or as a feedback pin to set a constant output voltage for powering OLED panels.

All trademarks are the property of their respective owners.

When configured as a dual output white LED bias supply, the LM3509 adaptively regulates the supply voltage of the LED strings to maximize efficiency and insure the current sinks remain in regulation. The maximum current per output is set via a single external low power resistor. An I²C compatible interface allows for independent adjustment of the LED current in either output from 0 to max current in 32 exponential steps. When configured as a white LED + OLED bias supply the LM3509 can independently and simultaneously drive a string of up to 5 white LED’s and deliver a constant output voltage of up to 21V for OLED panels.

Output over-voltage protection shuts down the device if V_OUT rises above 21V allowing for the use of small sized low voltage output capacitors. The LM3509 is offered in a small 10-pin thermally- enhanced WSON package and operates over the -40°C to +85°C temperature range.