SSPP66888877 4 CHANNEL REGULATED CHARGE PUMP WLED DRIVER 4 CHANNEL REGULATED CHARGE PUMP WLED DRIVER FEATURES Peak Efficiency: 90% Individual Current Regulation 3-bit Digital Output Control 1x and 1.5x Modes of Operation Current Matching with a Max Tolerance of 3% Output Current up to 30mA per LED Fixed Frequency of 1MHz Open LED Protection Pb-Free Thin QFN-16 3mmx3mm Package APPLICATIONS Cellular Phones Digital Cameras LED backlighting PDAs LCD Modules MP3 Players Handheld Devices DESCRIPTION The SP6887 is a 4-channel charge pump white LED driver, capable of driving up to 4 LEDs connected in parallel. The device operates in either 1x mode or 1.5x fractional mode, and it can switch from 1x mode to 1.5x mode automatically when the input voltage decreases. Its internal 4 current sink regulators ensure both LED current matching and brightness uniformity. The LED current can be programmed by an external resistor, R , connected SET between the RSET pin and ground. LED currents of up to 30mA are supported by the input supply voltage over a range of 2.7V to 5.5V, making the device optimized for Li-Ion battery applications. The SP6887 has a fixed switching frequency of 1MHz, allowing the use of very small value ceramic capacitors. The enable input pin allows the device to be placed in shutdown mode while reducing current consumption to less than 1A. LED dimming can be done by several methods including using a DC voltage to set the RSET pin current, adding a switched resistor in parallel with RSET or applying a PWM signal to CTRx pin or EN pin. TYPICAL APPLICATION CIRCUIT Rev. C 10/31/2007 SP6887 4 Channel WLED Driver 2007 Exar Corporation 1/10 BLOCK DIAGRAM Control Lines LED Output CTR2 CTR1 CTR0 LED4 LED3 LED2 LED1 0 0 0 - - - ON 0 0 1 - - ON - 0 1 0 - ON - - 0 1 1 ON - - - 1 0 0 - - ON ON 1 0 1 - ON ON ON 1 1 0 ON ON ON ON 1 1 1 - - - - 1 = Logic high (or V ), 0 = Logic low (or GND), - = LED output off IN Table 1: LED Enable Logic Rev. C 10/31/2007 SP6887 4 Channel WLED Driver 2007 Exar Corporation 2/10