GM2102

PRELIMINARY GM2102 CONSTANT CURRENT DC/DC WHITE LED DRIVER GENERAL DESCRIPTION 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. FEATURES • • • • • • • • 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 TYPICAL APPLICATION 6.8 uH D1 APPLICATIONS • • • • • • Cellular Phones Digital Cameras Handheld Computers Portable Audio players Pagers Other White LED applications Vin 2.7V to 4.2V 6 C1 4.7 uF 1 SW C2 1 uF Vin PWM DIMMING CONTROL SIGNAL 5 GM2102 SHDN Rset 4 Rset 1.5K LED GND 2 3 15mA Revision 1, March 2003 1 www.gammamicro.com PRELIMINARY GM2102 CONSTANT CURRENT DC/DC WHITE LED DRIVER ELECTRICAL CHARACTERISTICS PARAMETER Minimum Input Voltage Rset Pin Voltage LED Pin Voltage Quiescent Current Swithing Frequency Maximum Switch Duty Cycle Switch Current Limit Switch VCESAT SHDN Pin Current Switch Leakage Current ISW = 300 mA VSHDN = 0V VSHDN = 2V Switch OFF, VSW = 5V Rset = 562 Ω, Vin =1.5 V LED Pin Current Rset = 750 Ω, Vin =1.2 V Rset = 1.5K Ω, Vin =1.2 V Rset = 4.53KΩ, Vin =1.2 V LED Pin Current Temp Coeff. Start up Threshold (SHDN pin) Shutdown Threshold (SHDN pin) ILED =15 mA 0.85 0.25 20 0.1 40 30 15 5 -0.02 Rset = 1.5K Rset = 1.5K, Vin < Vout VRset = 0.2V VSHDN = 0V Vin = 1V 85 TEST CONDITIONS MIN GM2102 TYP 1.5 100 120 1.2 0.1 1.2 95 500 200 M AX 1.2 UNIT V mV mV 1.5 1 mA µA MHz % mA mV 0.1 30 µA µA µA mA mA mA mA mA/°C V 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 PARAMETER Vin Voltage Shutdown Voltage SW Voltage LED Voltage Junction Temperature Operating Temperature Range Storage Temperature Range Lead Temperature GM2102 10 10 40 40 125 -40 to 85 -65 to 150 300 UNIT V V V V °C °C °C °C Revision 1, March 2003 2 www.gammamicro.com PRELIMINARY GM2102 CONSTANT CURRENT DC/DC WHITE LED DRIVER PIN CONFIGURATION SW 1 6 V in GND 2 GM2102 5 SHDN LED 3 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 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. Revision 1, March 2003 3 www.gammamicro.com PRELIMINARY GM2102 CONSTANT CURRENT DC/DC WHITE LED DRIVER TYPICAL APPLICATIONS Vin 1.5 V 4.7 uH D1 Vin 1.5 V 4.7 uH D1 6 C1 4.7 uF 1 SW C2 2.2 uF C1 4.7 uF 6 Vin 1 SW C2 4.7 uF Vin GM2102 5 SHDN Rs et 4 24.9 K GM2102 3 5 SHDN LED GND 2 3 LED GND 2 15mA Rs et 4 24.9 K 15mA 2.5 V PWM DIMMING CONTROL Rset 1.5K 2.5 V PWM DIMMING CONTROL Rset 1.5K Single Cell Driver forTwo White LEDs Single Cell Driver for One White LED Vin 1.8 to 3 V 4.7 uH D1 Vin 1.8 to 3 V 4.7 uH D1 6 C1 4.7 uF 1 SW C2 2.2 uF C1 4.7 uF 6 Vin 1 SW C2 2.2 uF Vin GM2102 5 SHDN Rs et 4 60.4 K GM2102 3 5 SHDN LED GND 2 3 LED GND 2 15mA Rs et 4 60.4 K 15mA 2.5 V DC DIMMING CONTROL Rset 1.5K 2 .5 V DC DIMMING CONTROL Rset 1.5K Two Cell Driver forTwo White LEDs Two Cell Driver forThree White LEDs Revision 1, March 2003 4 www.gammamicro.com PRELIMINARY GM2102 CONSTANT CURRENT DC/DC WHITE LED DRIVER Vin 1.8 to 3 V 4.7 uH D1 Vin 1.8 to 3 V 4.7 uH D1 6 C1 4.7 uF 1 SW C2 1 uF C1 4.7 uF 6 Vin 1 SW C2 1 uF Vin GM2102 5 SHDN Rs et 4 LED GND 2 3 GM2102 5 SHDN Rs et 4 LED GND 2 3 PWM DIMMING CONTROL SIGNAL PWM DIMMING CONTROL SIGNAL 15mA Rset 1.5K Rset 1.5K 15mA Two Cell Driver for Four White LEDs Two Cell Driver for Five White LEDs Vin 2.7 to 4.2 V 6.8 uH D1 Vin 2.7 to 4.2 V 6.8 uH D1 6 C1 4.7 uF 1 SW C2 2.2 uF C1 4.7 uF 6 Vin 1 SW C2 2.2 uF Vin GM2102 5 SHDN Rs et 4 31.6 K GM2102 5 SHDN LED GND 2 3 LED GND 2 3 15mA Rs et 4 31.6 K 15mA 3 .3 V PWM DIMMING CONTROL Rset 1.5K 3.3 V PWM DIMMING CONTROL Rset 1.5K Li-Ion Driver forTwo White LEDs Li-Ion Driver for Three White LEDs Revision 1, March 2003 5 www.gammamicro.com PRELIMINARY GM2102 CONSTANT CURRENT DC/DC WHITE LED DRIVER Vin 2.7 to 4.2 V 6.8 uH D1 Vin 2.7 to 4.2 V 4.7 uH D1 6 C1 4.7 uF 1 SW C2 1 uF C1 4.7 uF 6 Vin 1 SW C2 1 uF Vin GM2102 5 SHDN R s et 4 LED GND 2 3 GM2102 PWM DIMMING CONTROL SIGNAL 5 SHDN Rs et 4 LED GND 2 3 PWM DIMMING CONTROL SIGNAL 15mA Rset 1.5K Rset 1.5K 15mA Li-Ion Driver for Four White LEDs Li-Ion Driver for Five White LEDs Vin 5V 10 uH D1 Vin 3 to 4.2 V 4.7 uH D1 6 C1 4.7 uF 1 SW C2 2.2 uF Vin 6 C1 4.7 uF 1 SW C2 1 uF GM2102 5 SHDN Rs et 4 51.1 K Vin LED GND 2 3 5 GM2102 SHDN Rs et 4 80.6 K LED GND 2 3 5 V DC DIMMING CONTROL 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