MAX1916 19-2067 Rev 0 7/01 Low-Dropout, Constant-Current Triple White LED Bias Supply General Description Features The MAX1916 low-dropout bias supply for white LEDs Low 200mV Dropout at 9mA is a high-performance alternative to the simple ballast Up to 60mA/LED Bias Current resistors used in conventional white LED designs. The MAX1916 uses a single resistor to set the bias current 0.3% LED Current Matching for three LEDs, which are matched to 0.3%. The Simple LED Brightness Control MAX1916 consumes only 40A of supply current when enabled and 0.05A when disabled. Low 40A Supply Current The MAX1916s advantages over ballast resistors Low 0.05A Shutdown Current include significantly better LED-to-LED bias matching, much lower bias variation with supply voltage variation, 2.5V to 5.5V Supply Voltage Range significantly lower dropout voltage, and in some appli- Thermal Shutdown Protection cations, significantly improved efficiency. The MAX1916 requires a 200mV dropout at a 9mA load on each out- Tiny 6-Pin Thin SOT23 Package (1mm High) put to match the LED brightness. The MAX1916 is available in a space-saving 6-pin Thin SOT23 package. Applications Ordering Information Next-Generation Wireless Handsets PIN- TOP PART TEMP. RANGE PACKAGE MARK PDAs, Palmtops, and Handy Terminals MAX1916EZT 6 Thin SOT23 -40C to +85C AAAG Digital Cameras, Camcorders Battery-Powered Equipment Typical Operating Circuit Pin Configuration V+ TOP VIEW V CTRL EN16 LED1 MAX1916 SET LED1 LED2 LED3 GND 2 5 LED2 ON OFF EN MAX1916 SET34 LED3 GND THIN SOT23-6 Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com.Low-Dropout, Constant-Current Triple White LED Bias Supply ABSOLUTE MAXIMUM RATINGS EN, SET, LED1, LED2, LED3 to GND ..................... -0.3V to +6V Operating Temperature Range ......................... -40C to +85C Continuous Power Dissipation (T = +70C) Storage Temperature Range ........................... -65C to +150C A 6-Pin Thin SOT23 (derate 9.1mW/C above +70C) ... 727mW Lead Temperature (soldering, 10s)................................... 300C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (V = 3.3V, V = V = V = 1V, T = -40C to +85C, unless otherwise noted. Typical values are at T = +25C.) (Note 1) EN LED1 LED2 LED3 A A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Operating Voltage Range V EN is the power-supply input 2.5 5.5 V EN V rising 2.2 2.47 V Undervoltage Lockout EN V UVLO Threshold Hysteresis 85 mV SET Input Current Range I 5 260 A SET SET to LED Current Ratio I /I , I = 42 A 207 230 253 A/A LED SET SET SET Bias Voltage V I = 42 A 1.154 1.215 1.276 V SET SET SET Leakage Current EN = GND, T = -40C to +25C 0.01 1 A A in Shutdown V = 3.3V SET T = -40C to +85C5 A LED -to-LED Current Matching I = 42A0.35% SET Maximum LED Sink Current I Each LED 60 mA LED I = 22 A (Note 2) 100 180 SET LED Dropout Voltage I = 42 A (Note 3) 200 360 mV SET I = 84 A (Note 3) 230 410 SET V = V = LED1 LED2 LED Leakage Current V = 5.5V, EN = T = +25C 0.01 1 A LED3 A in Shutdown GND, each LED Input High Voltage V V > V for enable 2.5 IH EN IH V Input Low Voltage V V < V for disable 2.2 IL EN IL V = 2.5V to 5.5V, EN is the power-supply EN 40 100 input EN Input Bias Current I A EN V = 0.4V T = +25C 0.05 1 EN A Thermal Shutdown Temperature 170 C Thermal Shutdown Hysteresis 10 C Note 1: Limits are 100% production tested at T = +25C. Limits over the operating temperature range are guaranteed through A correlation using statistical quality control (SQC) methods. Note 2: Dropout Voltage is defined as the LED to GND voltage at which current sink into LED drops 20% from the value at V = 1V. LED Note 3: Dropout Voltage is defined as the LED to GND voltage at which current sink into LED drops 10% from the value at V = 1V. LED 2 MAX1916