PT4101-White LED Step-Up Converter  PDF文档下载
PT4101:
● 小尺寸SOT23-6封装
● 输出具有20V过压保护
● 工作电压为3-5.5V
● 恒流驱动白光LED
● 可驱动3V的白光LED 五颗串联
● 效率高达87%
● 1.25MHZ固定的开关频率
● 超低的0.104V的采样电压
● 可实现PWM亮度控制
● 广泛应用于消费类产品，手机，PDA的背光驱动
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 constant 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 easily 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
¨ Drives Up to 5 Series White LEDs from 3V
¨ Up to 87% Efficiency
¨ 1.25MHz Fixed Switching Frequency
¨ Low 104mV Feedback Voltage
¨ Open Load Shutdown
¨ PWM Dimming
¨ SOT23-6 Packages
APPLICATIONS
¨ Cell Phones
¨ Handheld Computers and PDAs
¨ Digital Cameras
¨ Small LCD Displays
TYPICAL APPLICA TIONS
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