XC9270/XC9271 Series ETR05048-004 30 V Driver Transistor Built-In Step-Down DC/DC Converters GENERAL DESCRIPTION The XC9270/XC9271 series are 30V operation step-down DC/DC converter ICs with an internal driver transistor. The internal Nch driver transistor is driven by bootstrap to achieve a stable, high-efficiency power supply up to an output current of 2.0A. Low ESR capacitors such as ceramic capacitors can be used for the load capacitor (C ). L A 0.8V reference voltage source is incorporated in the IC, and the output voltage can be set to a value from 1.2V to 12.0V using external resistors (R , R ). FB1 FB2 300kHz or 500kHz can be selected for the switching frequency. The generation of unneeded noise can be suppressed by synchronizing to an external CLK in a range of 25% of the free running frequency using the SYNC pin. In automatic PWM/PFM control, the IC operates by PFM control when the load is light to achieve high efficiency over the full load range from light to heavy. The soft start time can be set as desired by adding an external capacitance to the SS pin. With the built-in UVLO function, the driver transistor is forced OFF when input voltage becomes 4.5V or lower. Internal protection circuits include over current protection, integral latch protection, short-circuit protection, and thermal shutdown circuits to enable safe use. FEATURES APPLICATIONS : 730V Car navigation systems Input Voltage Car audios : 0.8V (2) FB Voltage Industrial equipment : Oscillation Frequency 300kHz, 500kHz Maximum Output Current : 2.0A Control Method : PWM (XC9270) PWM/PFM (XC9271) External Capacitor : Soft-start (set by external capacitor C) : Protection Circuit Over Current Protection 3.2A (TYP.) Integral Latch Method (XC9270 / XC9271A) Automatic Recovery (XC9270 / XC9271B) Thermal Shutdown Low ESR Ceramic Capacitor : Ceramic Capacitor : -40 ~ +105 Operating Ambient Temperature Package : SOP-8FD Environmentally Friendly EU RoHS Compliant, Pb Free : *Performance depends on external components and wiring on the PCB. TYPICAL PERFORMANCE TYPICAL APPLICATION CIRCUIT CHARACTERISTICS XC9270x085/XC9271x085 C IN2 (V =12V , V =5V) IN OUT V GND IN L=15H(CLF12555-150M), C =10F(GRM32ER71H106KA12L), C IN1 IN1 SBD=CMS15, C =22F2(GRM32ER71E226KE15L) L 100 CE BST 90 C BST 80 L 70 SS Lx 60 SBD C SS 50 R FB1 C FB 40 30 SYNC FB C L XC9271 20 10 XC9270 R FB2 0 C SYNC 1 10 100 1000 10000 Output Current :I mA OUT 1/28 Efficiency :EFFI % XC9270/XC9271 Series BLOCK DIAGRAM 1) XC9270 Series, Type A LocalReg(=VL) V BST IN EachCircuit CEH Under Voltage SHP UVLO Buffer Lock Out CurrentSense OE TSD SHP Latch delay Short Circuit Lx Protection CurrentLimit - FB Err Amp - PWM Comparator VREF + PWM ControlLOGIC CEH + Soft Start SS Ramp EXT CLK OSC SYNC Wave Control Logic SHP Thermal Chip Enable CE CEH TSD Shutdown GND * Diodes inside the circuit are ESD protection diodes and parasitic diodes. 2) XC9270 Series, Type B LocalReg(=VL) V BST IN EachCircuit CEH Under Voltage SHP UVLO Buffer Lock Out CurrentSense OE TSD SHP Short Circuit Lx Protection CurrentLimit - FB Err Amp - PWM VREF + Comparator PWM ControlLOGIC CEH + Soft Start SS Ramp EXT CLK OSC SYNC Wave Control Logic SHP Thermal Chip Enable CE CEH TSD Shutdown GND * Diodes inside the circuit are ESD protection diodes and parasitic diodes. 2/28