MIC2289C White LED Driver Internal Schottky Diode and OVP General Description Features The MIC2289C is a PWM (pulse width modulated), boost- 2.5V to 10V input voltage switching regulator that is optimized for constant-current Output voltage up to 34V with OVP white LED driver applications. The MIC2289C features an Internal Schottky diode internal Schottky diode and three levels of output 1.2 MHz PWM operation overvoltage protection providing a small size and efficient DC/DC solution that requires only four external Over 500mA switch current components. 95mV feedback voltage To optimize efficiency, the feedback voltage is set to only <1% line and load regulation 95mV. This reduces power dissipation in the current set <1A shutdown current resistor and allows the lowest total output voltage, hence Overtemperature protection minimal current draw from the battery. UVLO The MIC2289C implements a constant frequency 1.2MHz Thin SOT-23 6-pin package PWM control scheme. The high frequency, PWM operation saves board space by reducing external component sizes. 40C to +125C junction temperature range The added benet of the constant frequency PWM scheme For higher performance specifications see the MIC2289 in caparison to variable frequency is much lower noise and input ripple injected to the input power source. Applications The MIC2289C clamps the output voltage in case of open White LED driver for backlighting: LED conditions, protecting itself and the output capacitor. Cell phones The MIC2289C is available with an output OVP option of PDAs 34V. GPS systems The MIC2289C is available in low profile 6-pin Thin SOT- 23 package. The MIC2289C has a junction temperature Digital cameras range of 40C to +125C. MP3 players Data sheets and support documentation can be found on IP phones Micrels web site at: www.micrel.com. LED ashlights Constant current power supplies Typical Application 10H 3-Series LED Efficiency 82 80 MIC2289C-34YD6 78 VIN SW 1-Cell 1F 76 Li Ion 0.22F/50V OUT 95mV 74 EN FB GND 72 V =3.6V IN 70 0 5 10 15 20 25 I (mA) OUT 7-Series White LED Driver MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc. Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC2289C Ordering Information Marking Overoltage Junction Part Number Code Protection Temp. Range Package Lead Finish MIC2289C-34BD6 SM34 34V 40C to +125C 6-Pin Thin SOT-23 Standard MIC2289C-34YD6 SM34 34V 40C to +125C 6-Pin Thin SOT-23 Pb-Free Note: Marking bars may not be to scale. Pin Configuration FB GND SW 3 2 1 Denotes Denotes MIC2289C Pb-Free SM34 4 5 6 EN VIN VOUT 6- Pin Thin SOT-23 (D6) Pin Description Pin Number Pin Name Pin Name 1 SW Switch node (Input): Internal power BIPOLAR collector. 2 GND Ground (Return): Ground. 3 FB Feedback (Input): Output voltage sense node. Connect the cathode of the LED to this pin. A resistor from this pin to ground sets the LED current. 4 EN Enable (Input): Logic high enables regulator. Logic low shuts down regulator. 5 VIN Supply (Input): 2.7V to 8V for internal circuitry. 6 OUT Output Pin and Overvoltage Protection (Output): Connect to the output capacitor and LEDs. M9999-081507-B August 2007 2