LM3535 Datasheet, PDF (1/26 Pages) National Semiconductor (TI) – Multi-Display LED Driver with Ambient Light Sensing and Dynamic Backlight Control Compatibility

LM3535
August 12, 2010
Multi-Display LED Driver with Ambient Light Sensing and
Dynamic Backlight Control Compatibility
General Description
The LM3535 is a highly integrated LED driver capable of driv-
ing 8 LEDs in parallel for large display applications. Indepen-
dent LED control allows for a subset of the 6 main display
LEDs to be selected for partial illumination applications. In
addition to the main bank of 6, the LM3535 is capable of driv-
ing an additional 2 independently controlled LEDs to support
Indicator applications.
The LED driver current sinks are split into three independently
controlled groups. The primary group can be configured to
drive up to six LEDs for use in the main phone display. Groups
B and C are provided for driving secondary displays, keypads
and indicator LEDs. All of the LED current sources can be
independently turned on and off providing flexibility to address
different application requirements.
The LM3535 provides multi-zone Ambient Light Sensing (1 or
2 ALS inputs depending on option) allowing autonomous
backlight intensity control in the event of changing ambient
light conditions. A PWM input is also provided to give the user
a means to adjust the backlight intensity dynamically based
upon the content of the display.
The LM3535 provides excellent efficiency without the use of
an inductor by operating the charge pump in a gain of 3/2 or
in Pass-Mode. The proper gain for maintaining current regu-
lation is chosen, based on LED forward voltage, so that
efficiency is maximized over the input voltage range.
The LM3535 is available in National’s tiny 20-bump, 0.4mm
pitch, thin micro SMD package.
Features
■ ^{Drives up to 8 LEDs with up to 25mA of Diode Current}
Each
■ ^{External PWM input for Dynamic Backlight Control}
■ ^{Multi-Zone Ambient Light Sensing (ALS)}
■ ^{Dual-ALS Sensor Inputs (LM3535-2ALS only)}
■ ^{ALS Interrupt Reporting}
■ ^{Independent On/Off Control for all Current Sinks}
■ ^{128 Exponential Dimming Steps with 600:1 Dimming Ratio}
for Group A (Up to 6 LEDs)
■ ^{8 Linear Dimming States for Groups B (Up to 3 LEDs) and}
D1C (1 LED)
■ ^{Programmable Auto-Dimming Function}
■ ^{Up to 90% Efficiency}
■ ^{0.55% Accurate Current Matching}
■ ^{Internal Soft-Start Limits Inrush Current}
■ ^{True Shutdown Isolation for LEDs}
■ ^{Wide Input Voltage Range (2.7V to 5.5V)}
■ ^{Active High Hardware Enable}
■ ^{Total Solution Size < 16mm2}
■ ^{Low Profile 20 Bump micro SMD Package}
(1.650mm × 2.055mm × 0.6mm)
Applications
■ ^{Smart-Phone LED Backlighting}
■ ^{Large Format LCD Backlighting}
■ ^{General LED Lighting}
Typical Application Circuit
30082468
© 2010 National Semiconductor Corporation 300824
Minimum Layout
30082441
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