LM3530

• Drives up to 11 LEDs in series
• 1000:1 Dimming Ratio
• 90% Efficient
• Programmable Dual Ambient Light Sensor Inputs
  with Internal ALS Voltage Setting Resistors
• I²C Programmable Logarithmic or
  Linear Brightness Control
• External PWM Input for Simple Brightness
  Adjustment
• True Shutdown Isolation for LEDs and Ambient
  Light Sensors
• Internal Soft-Start Limits Inrush Current
• Wide 2.7-V to 5.5-V Input Voltage Range
• 40-V and 25-V Overvoltage Protection Options
• 500-kHz Fixed Frequency Operation
• 839-mA Peak Current Limit

The LM3530 current mode boost converter supplies the power and controls the current in up to 11 series white LEDs. The 839-mA current limit and 2.7-V to 5.5-V input voltage range make the device a versatile backlight power source ideal for operation in portable applications.

The LED current is adjustable from 0 mA to 29.5 mA via an I²C-compatible interface. The 127 different current steps and 8 different maximum LED current levels give over 1000 programmable LED current levels. Additionally, PWM brightness control is possible through an external logic level input.

The device also features two Ambient Light Sensor inputs. These are designed to monitor analog output ambient light sensors and provide programmable adjustment of the LED current with changes in ambient light. Each ambient light sensor input has independently programmable internal voltage setting resistors which can be made high impedance to reduce power during shutdown. The 500-kHz switching frequency allows for high converter efficiency over a wide output voltage range accommodating from 2 to 11 series LEDs. Finally, the support of Content Adjusted Backlighting maximizes battery life while maintaining display image quality.

The LM3530 operates over the −40°C to 85°C temperature range.