1.25MHz固定开光频率,低反馈电压,支持开路保护和脉宽调制调光芯片PT4101

GENERAL DESCRIPTION The PT4101 is a step-up DC/DC converter designed for driving up to 5 white LEDs in series from a single cell Lithium Ion battery with cons tant current. Because it directly regulates output current, the PT4101 is ideal for driving light emitting diodes (LEDs) whose light intensity is proportional to the current passing through them, not the voltage across their terminals. A single external resistor sets LED current between 2mA and 20mA, which can then be eas ily adjusted using either a DC voltage or a pulse width modulated (PWM) signal up to 100KHz. Its low 104mV feedback voltage reduces power loss and improves efficiency. The OV pin monitors the output voltage and turns off the converter if an over-voltage condition is present due to an open circuit condition. The PT4101 is available in SOT23-6 packages. FEATURES z Drives Up to 5 Series White LEDs from 3V z Up to 87% Efficiency z 1.25MHz Fixed Switching Frequency z Low 104mV Feedback Voltage z Open Load Shutdown z PWM Dimming z SOT23-6 Packages z RoHS compliant APPLICATIONS z Cell Phones z Handheld Computers and PDAs z Digital Cameras z Small LCD Displays
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