GM2102 PRELIMINARY CONSTANT CURRENT DC/DC WHITE LED DRIVER GENERAL DESCRIPTION FEATURES The GM2102 is a member of Gamma Microelectronics’s family of white LED drivers. The GM2102 is a fixed frequency step-up DC/DC converter designed to operate as a constant-current source. It is ideal for driving light emitting diodes (LEDs) whose light intensity is proportional to the current passing through them and not on the voltage across their terminals as it directly regulates the output current. The wide input voltage range allows the device to work from a variety of input sources. A single external resistor sets LED current between 5mA and 40mA, which can then be easily adjusted using either a DC voltage or a PWM signal. In Shutdown mode, the LED’s are disconnected from the output with the maximum quiescent current of 1µA for the entire circuit. • • • • • • TYPICAL APPLICATION APPLICATIONS • • • • • • D1 6.8 uH Vin • • 2.7V to 4.2V 6 PWM DIMMING CONTROL SIGNAL SW GM2102 5 SHDN Rset 4 Revision 1, March 2003 Cellular Phones Digital Cameras Handheld Computers Portable Audio players Pagers Other White LED applications 1 Vin C1 4.7 uF Drives Six White LED’s from 1.8 V 1.2Mhz Fixed Frequency Switching Minimum operating input voltage 1.2V 90% efficiency Accurately adjustable LED current Current Regulation even when Vin > Vout Disconnects LED’s in Shutdown mode Available in SOT23 Package ideal for space conscious portable applications Rset 1.5K LED GND C2 1 uF 3 15mA 2 1 www.gammamicro.com GM2102 PRELIMINARY CONSTANT CURRENT DC/DC WHITE LED DRIVER ELECTRICAL CHARACTERISTICS PARAMETER TEST CONDITIONS MIN Minimum Input Voltage GM2102 TYP MAX 1.5 1.2 UNIT V Rset Pin Voltage Rset = 1.5K 100 mV LED Pin Voltage Rset = 1.5K, Vin < Vout 120 mV VRset = 0.2V 1.2 1.5 VSHDN = 0V 0.1 1 Vin = 1V 1.2 MHz 95 % 500 mA 200 mV Quiescent Current Swithing Frequency Maximum Switch Duty Cycle 85 Switch Current Limit Switch VCESAT SHDN Pin Current Switch Leakage Current LED Pin Current LED Pin Current Temp Coeff. ISW = 300 mA VSHDN = 0V VSHDN = 2V 20 mA µA 0.1 µA 30 µA Switch OFF, VSW = 5V 0.1 µA Rset = 562 Ω, Vin =1.5 V 40 mA Rset = 750 Ω, Vin =1.2 V 30 mA Rset = 1.5K Ω, Vin =1.2 V 15 mA Rset = 4.53KΩ, Vin =1.2 V 5 mA -0.02 mA/°C ILED =15 mA Start up Threshold (SHDN pin) 0.85 Shutdown Threshold (SHDN pin) V 0.25 V All Specification are at 25 °C. Vin = 1.8 V, VSHDN = 1.8 V unless otherwise noted. Specifications subject to change without notice. All performance characteristics based on the use of Gamma Microelectronics inc. application circuits. Functional Operation of the device at conditions beyond those specified here is not implied. ABSOLUTE MAXIMUM RATINGS GM2102 UNIT Vin Voltage 10 V Shutdown Voltage 10 V SW Voltage 40 V PARAMETER LED Voltage 40 V Junction Temperature 125 °C Operating Temperature Range -40 to 85 °C Storage Temperature Range -65 to 150 °C 300 °C Lead Temperature Revision 1, March 2003 2 www.gammamicro.com GM2102 PRELIMINARY CONSTANT CURRENT DC/DC WHITE LED DRIVER PIN CONFIGURATION SW 1 GND 2 LED 3 GM2102 6 V in 5 SHDN 4 R set 6 Lead Plastic SOT23 Package PIN FUNTIONS Pin SW (Pin 1) SWITCH PIN GND (Pin 2) GROUND PIN LED (Pin 3) LED PIN Rset (Pin 4) RESISTOR PIN SHDN ( Pin 5) SHUTDOWN PIN Vin (Pin 6) INPUT SUPPLY PIN Revision 1, March 2003 Function Collector terminal of the Internal NPN Power Switch Ground Reference Pin for the device Collector terminal of the Internal NPN LED Switch to be connected to the cathode of the last (bottom most) LED. The terminal that would connect the external resistor to the device to program the current that flows in the LED pin. Pin used to control the GM2102 to operate in active mode (Set to above V) or shutdown mode (below V) Input Pin to provide the input supply voltage to the device. 3 www.gammamicro.com GM2102 PRELIMINARY CONSTANT CURRENT DC/DC WHITE LED DRIVER TYPICAL APPLICATIONS D1 4.7 uH Vin 1.5 V D1 4.7 uH Vin 1.5 V 6 1 Vin C1 4.7 uF 6 SW C2 2.2 uF LED SHDN 3 5 C2 4.7 uF LED SHDN 15mA GND Rs et 4 SW GM2102 GM2102 5 1 Vin C1 4.7 uF 4 24.9 K 15mA GND Rs et 2 3 2 24.9 K 2.5 V PWM DIMMING CONTROL 2.5 V PWM DIMMING CONTROL Rset 1.5K Single Cell Driver forTwo White LEDs Single Cell Driver for One White LED D1 4.7 uH Vin Rset 1.5K D1 4.7 uH Vin 1.8 to 3 V 1.8 to 3 V 6 1 Vin C1 4.7 uF 6 SW C2 2.2 uF GM2102 5 SHDN Rs et 4 SW C2 2.2 uF GM2102 LED 3 GND 5 SHDN 15mA Rs et 2 LED 3 15mA GND 2 4 60.4 K 2.5 V DC DIMMING CONTROL 1 Vin C1 4.7 uF 60.4 K 2.5 V DC DIMMING CONTROL Rset 1.5K Two Cell Driver forThree White LEDs Two Cell Driver forTwo White LEDs Revision 1, March 2003 Rset 1.5K 4 www.gammamicro.com GM2102 PRELIMINARY CONSTANT CURRENT DC/DC WHITE LED DRIVER D1 4.7 uH Vin D1 4.7 uH Vin 1.8 to 3 V 1.8 to 3 V 6 1 6 Vin C1 4.7 uF SW C2 1 uF PWM DIMMING CONTROL SIGNAL LED SHDN 3 5 PWM DIMMING CONTROL SIGNAL GND Rs et 4 SW C2 1 uF GM2102 GM2102 5 1 Vin C1 4.7 uF GND Rs et 4 2 3 LED SHDN 2 15mA Rset 1.5K Rset 1.5K 15mA Two Cell Driver for Five White LEDs Two Cell Driver for Four White LEDs D1 6.8 uH Vin 2.7 to 4.2 V D1 6.8 uH Vin 2.7 to 4.2 V 1 6 Vin C1 4.7 uF 6 SW C2 2.2 uF GM2102 Rs et LED 3 GND 5 SHDN 15mA Rs et 2 4 C2 2.2 uF LED 3 GND 15mA 2 4 31.6 K 3.3 V PWM DIMMING CONTROL SW GM2102 5 SHDN 1 Vin C1 4.7 uF 31.6 K 3.3 V PWM DIMMING CONTROL Rset 1.5K Li-Ion Driver for Three White LEDs Li-Ion Driver forTwo White LEDs Revision 1, March 2003 Rset 1.5K 5 www.gammamicro.com GM2102 PRELIMINARY CONSTANT CURRENT DC/DC WHITE LED DRIVER D1 6.8 uH Vin 2.7 to 4.2 V D1 4.7 uH Vin 2.7 to 4.2 V 6 1 6 Vin C1 4.7 uF SW C2 1 uF GM2102 5 3 PWM DIMMING CONTROL SIGNAL GND Rs et 5 LED SHDN C2 1 uF 3 GND Rs et 2 4 2 4 SW GM2102 LED SHDN PWM DIMMING CONTROL SIGNAL 1 Vin C1 4.7 uF 15mA Rset 1.5K Rset 1.5K 15mA Li-Ion Driver for Five White LEDs Li-Ion Driver for Four White LEDs D1 10 uH Vin 5V D1 4.7 uH Vin 3 to 4.2 V 6 1 Vin C1 4.7 uF SW 6 C2 2.2 uF GM2102 5 LED SHDN 1 Vin C1 4.7 uF SW GM2102 3 5 SHDN Rs et C2 1 uF LED 3 GND Rs et 2 4 5 V DC DIMMING CONTROL GND 2 4 51.1 K 80.6 K 3.3 V DC DIMMING CONTROL Rset 1.5K 15mA 100 ohms Rset 750 ohms 100 ohms 30mA Li-Ion Driver for Eight White LEDs 5V Driver for 16 White LEDs Revision 1, March 2003 6 www.gammamicro.com