MIC2297-38YML TR Microchip

MIC2297 40V PWM Boost Regulator White LED Driver General Description Features The MIC2297 is a 600KHz PWM boost-switching regulator 2.5V to 10V input voltage range that is optimized for driving 6-10 series white LEDs. With Output voltage up to 40V its internal 40V switch and a guaranteed switch current of 1.2A switch current 1.2A, the MIC2297 easily drives a string of 10 white LEDs 600KHz PWM operation in series at 20mA, ensuring a high level of brightness and eliminating several ballast resistors. Trimmed 200mV feedback voltage Output over voltage protection (fixed or adjustable) The MIC2297 implements constant frequency 600KHz PWM Brightness Control PWM control. The high frequency PWM operation saves DAC Brightness Control board space by reducing external component sizes. The added benefit of the constant frequency PWM operation is <1% line regulation much lower noise and input ripple injected back to the 1A shutdown current battery source than with variable frequency topologies. Over temperature protection To optimize efficiency, the feedback voltage is set to UVLO 200mV. This reduced voltage reduces the power 10-pin 2.5mm x 2.5mm MLF package dissipation in the current set resistor, and allows the lowest o o 40 C to +125 C junction temperature range total output voltage, hence minimal current draw from the battery. Applications The MIC2297 is available with output over-voltage PDAs protection that protects the IC and external components in case of open LED conditions. GPS systems Smart phones The MIC2297 is available in low profile small size 10-pin Mini PCs 2.5mm x 2.5mm MLF package. The MIC2297 has a junction temperature range of 40C to +125C. Digital cameras IP phones LED flashlights Typical Applications 6.8H-22H 6.8H-22H SW SW VIN VIN 0.47F 0.47F 1F 1F 1-Cell EN OVP 1-Cell PWM EN OVP /50V /50V MIC2297 MIC2297 Li Ion Li Ion -42BML -42BML BRT BRT 3V to 4.2V 3V to 4.2V FB FB REF REF 1F AGND PGND COMP AGND PGND COMP 1F 10 10 0.1F 0.1F 10 Series LED Driver with Output OVP 10 Series LED Driver with PWM Brightness Control MLF and MicroLeadFrame is a trademark 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. MIC2297 Ordering Information Output Over Junction Part Number Mark Code* Lead Finish Package Voltage Protection Temp. Range MIC2297-15YML S115 Pb-Free 15V 40C to 125C 10-Pin 2.5 x2.5 MLF MIC2297-42YML S142 42V 40C to 125C 10-Pin 2.5 x2.5 MLF Pb-Free * ( ) Top bar symbol after PI indicator identifying Pb-Free may not be to scale. Pin Configuration PGND 1 10 SW OVP 2 9 FB VIN 3 8 REF EN 4 7 BRT COMP 5 6 AGND Pin Description Pin Number Pin Name Pin Function 1 PGND Ground (Return). Over Voltage Protection (Input): Connect to the output to clamp the maximum output voltage. A resistor divider from 2 OVP this pin to ground could be used to raise the OVP level of the 15V OVP option. 3 VIN Supply (Input): Input voltage. Enable (Input): Logic high enables regulator. Logic low shuts 4 EN down regulator. 5 COMP Compensation Pin. Analog Ground. 6 AGND Brightness Control (Input): Either an analog (DAC) or filtered PWM signal can be used. The gain equation is: VFB = 7 BRT VBRT / 5. This pin should be left open if the brightness function is not used. In that case, the FB will be set to its default value of 200mV. Reference Voltage (Output): This node is equal to the voltage on the FB pin. A capacitor from REF to ground should be used to filter the BRT voltage if PWM dimming is 8 REF implemented. A capacitor from REF to ground can also be used to implement a soft-start function. This pin can be left open if not used. Feedback (Input): Output voltage sense node. Default value 9 FB is 200mV. Connect the cathode of the LED chain to this pin. Connect current set resistor from this pin to ground. 10 SW Switch Node (Output): Internal power BIPOLAR collector. EPad GND Ground (Return): Backside pad. M9999-032708 Mach 2008 2