LTC3220 Datasheet

• Eighteen 20mA Universal Current Sources with 64-Step Linear Brightness Control
• Independent On/Off, Brightness Level, Blinking and Gradation Control for Each Current Source Using 2-Wire I²C Interface
• Low Noise Multi-Mode Charge Pump (1x, 1.5x, 2x) Provides Up to 91% Efficiency
• Slew Limited Switching Reduces Conducted and Radiated Noise (EMI)
• Up to 360mA Total Output Current
• Internal Current Reference
• Single Reset Pin for Asynchronous Shutdown and Reset of All Data Registers
• Two I²C Addresses Are Available (LTC3220: 0011100)
• Automatic or Forced Mode Switching
• Internal Soft-Start Limits Inrush Current
• Short-Circuit/Thermal Protection
• 4mm × 4mm Ultrathin (0.55mm) 28-Lead QFN Package

• Video Phones with QVGA+ Displays
• Keypad Lighting
• General/Miscellaneous Lighting

The LTC3220 are highly integrated multi-display LED drivers. These parts contain a high efficiency, low noise charge pump to provide power to up to eighteen universal LED current sources. The LTC3220 require only five small ceramic capacitors to form a complete LED power supply and current controller.

The LED currents are set by an internal precision current reference. Independent dimming, on/off, blinking and gradation control for all universal current sources is achieved via the I²C serial interface. 6-bit linear DACs are available to adjust brightness levels independently for each universal LED current source.

The LTC3220 charge pump optimizes efficiency based on the voltage across the LED current sources. The part powers up in 1x mode and will automatically switch to boost mode whenever any enabled LED current source begins to enter dropout. The first dropout switches the parts into 1.5x mode and a subsequent dropout switches the LTC3220 into 2x mode. The parts reset to 1x mode whenever a data bit is updated via the I²C port.