Complete lighting solution for smartphone handsets - LM3533

LM3533 (ACTIVE)

Complete lighting solution for smartphone handsets

Description

The LM3533 is a complete power source for backlight, keypad, and indicator LEDs in smartphone handsets. The high-voltage inductive boost converter provides the power for two series LED strings for display backlight and keypad functions (HVLED1 and HVLED2). The integrated charge pump provides the bias for the five low-voltage indicator LED current sinks (LVLED1 to LVLED5). All low-voltage current sinks can have a programmable pattern modulated onto their output current for a wide variety of blinking patterns.

Additional features include a pulse width modulation (PWM) control input for content adjustable backlight control (CABC), and an ambient light sensor interface (ALS) with an internal 8-bit ADC to provide automatic current adjustment based upon ambient light conditions. Both the PWM and ALS inputs can be used to control any high- or low-voltage current sink.

The LM3533 is fully programmable via an I2C-compatible interface. The device is available in a 20-pin DSBGA and operates over a 2.7-V to 5.5-V input voltage range and a −40°C to +85°C temperature range.

Features

  • Drives Two Parallel High-Voltage LED Strings for
    Display and Keypad Lighting
  • High-Voltage Strings Capable of up to 40-V
    Output Voltage and up to 90% Efficiency
  • Up to 30 mA per Current Sink (Both Backlight and
    Indicator)
  • 14-Bit Equivalent Exponential Dimming With 8-Bit
    Programmable Backlight Code
  • Selectable Analog ALS Input with 128
    Programmable Gain-Setting Resistors or PWM
    ALS Input With Internal Low-Pass Filter
  • PWM Input for Content Adjustable Brightness
    Control
  • Five Low-Voltage Current Sinks for Indicator LEDs
  • Integrated Charge Pump for Improved Efficiency
    and VIN Operating Range
  • Internal Pattern Generation Engine
  • Fully Configurable LED Grouping and Control
  • Four Programmable Overvoltage Protection
    Thresholds (16 V, 24 V, 32 V, and 40 V)
  • Programmable 500-kHz and 1-MHz Switching
    Frequency
  • 27-mm2 Total Solution Size

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Parametrics Compare all products in Backlight

 
Channels (#)
Vin (Min) (V)
Vin (Max) (V)
Vout (Max) (V)
Switching Frequency (Max) (kHz)
Type
LED Current Per Channel (mA)
LED (#)
Topology
Shutdown Current (Typ) (uA)
Peak Efficiency (%)
LED Configuration
Special Features
Rating
Pin/Package
Approx. Price (US$)
LM3533
7    
2.7    
5.5    
40    
1000    
Inductive    
30    
25    
Boost    
1    
88    
Parallel    
OVP    
Catalog    
20DSBGA    
0.70 | 1ku    

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