Preliminary Datasheet LP6270 High Efficiency, Boost Convertor with Programmable Current Limit Features General Description The LP6270 is a current mode boost DC-DC converter. Its PWM circuitry with built-in 2.6A Current power MOSFET makes this converter highly power efficiently. The non-inverting input its error amplifier is Up to 94% efficiency Output to Input Disconnect at Shutdown Mode Output voltage Up to 5V Low Quiescent Current:16Ua Built-In Short-Circuit Protection Built-in Thermal Protection RoHS Compliant and 100% Lead (Pb)-Free connected to an internal 0.6V precision reference voltage. Soft-Start time can be programmed with an external capacitor, which sets the input current ramp Pin Configurations rate. A built-in charge pump is used to drive the N-Channel MOSFET that is free of parasitic body diode to eliminate any reversed current flow across the switch when it is powered off. Its low quiescent current (16μA) and small package (QFN-10) is particularly suitable in battery-powered portable equipment. Several protection functions include soft start to limit inrush current during plug-in, current limiting at 1500mA to meet USB power requirement, and thermal shutdown to protect damage under over current conditions. Order Information LP6270 □ □ □ F: Pb-Free Applications Battery products Host Products Panel Power Switch USB Device Battery Charger Circuits Package Type QFN-10 Marking Information Device Marking Package Shipping LP6270 LPS QFN-10 3K/Set LP6270 xxxx LP6270QVF Version 1.0 Datasheet NOV.-2013 www.lowpowersemi.com Page 1 of 6 Preliminary Datasheet LP6270 Typical Application Circuit Functional Pin Description Pin Number Pin Name Pin Function 1 FB1 Feedback Reference Voltage Pin. Series connect a resistor between WLED and ground as a current sense. Sense the current feedback voltage to set the current rating. 2 GND 3 SW Ground Pin Switch Pin. Connect this Pin to inductor and catch diode. Minimize the track area to reduce EMI. 4 VDD2 5 EN2 Working Voltage within the Device Chip Enable (Active High). Voltage sensing input to trigger the function of over voltage protection. Note that this pin is high impedance. There should be a pull low 100kΩ resistor connected to GND when the control signal is floating. 6 ISET2 Charge Current Set Input. 7 VOUT Output pin. 8 ISET1 Charge Current Set Input. 9 VDD1 Working Voltage within the Device. 10 EN1 Chip Enable (Active High). Voltage sensing input to trigger the function of over voltage protection. Note that this pin is high impedance. There should be a pull low 100kΩ resistor connected to GND when the control signal is floating. LP6270QVF Version 1.0 Datasheet NOV.-2013 www.lowpowersemi.com Page 2 of 6 Preliminary Datasheet LP6270 Function Block Diagram LP6270QVF Version 1.0 Datasheet NOV.-2013 www.lowpowersemi.com Page 3 of 6 Preliminary LP6270 Datasheet Absolute Maximum Ratings Input Voltage to GND -----------------------------------------------------------------------------7V EN Voltage ------------------------------------------------------------------------------------------0.3V to 7V Operation Junction Temperature Range ---------------------------------------------------−40°C to 125°C Maximum Soldering Temperature (at leads, 1 0sec) --------------------------------------300℃ Maximum Power Dissipation (PD) --------------------------------------------------------------0.25W Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------- 260°C Electrical Characteristics Parameter Symbol Test Condition Min Typ. Max Units 5.5 V System Supply Input Operation voltage Range VDD Under Voltage Lock Out VDD Supply Current IDD FB=0V, Switching 0.8 1.3 mA Shut Down Current IDD VEN < 0.4V 0.1 1 uA Line Regulation 2.7 2.4 VIN : 3.0~4.3V V 2 % 1.1 MHz 92 % 600 mV 0.3 Ω Boost OCP 2600 mA Current Limit OCP 1500 mA Oscillator Operation Frequency 0.8 FOSC Maximum Duty Cycle Feedback Voltage MOSFET On Resistance of MOSFET RDS(ON) Protection Shut Down Voltage VEN Enable Voltage VEN LP6270QVF Version 1.0 Datasheet NOV.-2013 0.4 1.5 www.lowpowersemi.com V V Page 4 of 6 Preliminary Datasheet LP6270 Applications Information The LP6270 uses a 1.2MHz fixed-frequency, current-mode regulation architecture to regulate the output voltage. The LP6270 measures the output voltage through an external resistive voltage divider and compares that to the internal 0.6V reference to generate the error voltage to the inductor current to regulate the output voltage. the use of current-mode regulation improves transient response and control loop stability. Current Limitation The internal power-MOS switch current is monitored cycle-by-cycle and is limited to the value not exceed 2.6A (Typ.). When the switch current reaches the limited value, the internal power-MOS is turned off immediately until the next cycle. Keep traces at this pin as short as possible. Do not put capacitance at this pin. Inductor Selection For a better efficiency in high switching frequency converter, the inductor selection has to use a proper core material such as ferrite core to reduce the core loss and choose low ESR wire to reduce copper loss. The most important point is to prevent the core saturated when handling the maximum peak current. Using a shielded inductor can minimize radiated noise in sensitive applications. The maximum peak inductor current is the maximum input current plus the half of inductor ripple current. The calculated peak current has to be smaller than the current limitation in the electrical characteristics. A typical setting of the inductor ripple current is 20% to 40% of the maximum input current. If the selection is 40%, the maximum peak inductor current is The minimum inductance value is derived from the following equation : Depending on the application, the recommended inductor value is between 2.2μH to 10μH. LP6270QVF Version 1.0 Datasheet NOV.-2013 www.lowpowersemi.com Page 5 of 6 Preliminary Datasheet LP6270 Packaging Information DETAIL A Pin#1 ID and TIE Bar Mark Options Note: The configuration of Pin #1 identifier is optional, but must be located within the zone indicated. Symbol Dimensions in Millimeters Dimensions in Inches Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.180 0.300 0.007 0.012 D 2.950 3.050 0.116 0.120 D2 2.300 2.650 0.091 0.104 E 2.950 3.050 0.116 0.120 E2 1.500 1.750 0.059 0.069 e L LP6270QVF Version 1.0 Datasheet 0.500 0.350 0.450 NOV.-2013 www.lowpowersemi.com 0.020 0.014 0.018 Page 6 of 6