LM3509SDX

• Integrated OLED display power supply and LED driver
• It can drive up to 30 mA of up to 10 LEDs
• Delivers up to 40 mA to 21V when driving 20mA for 5 LEDs
• More than 90% efficiency
• 32 Exponential dimming steps
• 0.15% accurate current matching between strings
• Internal soft start limits inrush current
• True shutdown isolation of LEDs
• Input voltage range from 2.7V to 5.5V
• 21V overvoltage protection
• 1.27MHz fixed frequency operation
• Thin 10-Pin LLP Package (3× 3 ×0.8 mm)
• Universal I/O
• Active low hardware reset

illustrate

The LM3509 current-mode boost converter provides two separate outputs. The first output (main) is a constant irradiation current that drives the series white LEDs. The second output (SUB/FB) is a configurable series of white LEDs with a bias set as a feedback pin for a constant sink current or constant output voltage to power the OLED panel.

When configured with a dual-output white LED bias power supply, the LM3509 adaptively adjusts the power supply voltage of the LED string to maximize efficiency and ensure that the current suck is regulated. The maximum current per output is through an external low-power resistor. One me 2 The C-compatible interface allows independent LED current adjustment, whether from 0 to a maximum of 32 exponential step current outputs. When configured as a white LED + OLED bias power supply, the LM3509 can drive a string of 5 white LEDs and OLED panels at the same time to provide a constant output voltage up to 21V.

If the output overvoltage protection function is turned off on the device, the above allows the use of a small low-voltage output capacitor of 21V, V OUT rises. The LM3509 is available in a small, 10-pin, thermally enhanced LLP package that operates over a temperature range of -40°C to +85°C.

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• Dual display backlight in portable applications
• Large format LCD backlight
• OLED panel power supply