XC9257/XC9258 Series ETR05040-002 COT Control, 1.0A Synchronous Step-Down DC/DC Converters GreenOperation-compatible GENERAL DESCRIPTION The XC9257/XC9258 series is a group of synchronous-rectification type DC/DC converters with a built-in P-channel MOS driver transistor and N-channel MOS switching transistor, designed to allow the use of ceramic capacitors. Output voltage is internally set in a range from 0.8V to 3.6V (accuracy: 2.0%) increments of 0.05V. The device provides a high efficiency, stable power supply with an output current of 1.0A to be configured using only a coil and two capacitors connected externally. Oscillation frequency is set to 1.2MHz or 6.0MHz can be selected for suiting to your particular application. (*) As for operation mode HiSAT-COT control excellent in transient response, the XC9257 series is PWM control, the XC9258 series is automatic PWM/PFM switching control, allowing fast response, low ripple and high efficiency over the full range of loads (from light load to heavy load). During stand-by, all circuits are shutdown to reduce current consumption to as low as 1.0 A or less. As for the soft-start function as fast as 0.3ms in typical for quick turn-on. With the built-in UVLO (Under Voltage Lock Out) function, the internal P-channel MOS driver transistor is forced OFF when input voltage becomes 2.00V or lower. The B types integrate C High Speed discharge L function which enables the electric charge at the output capacitor C to be discharged via the internal discharge. L Two types of package SOT-25, USP-6C are available. (*) HiSAT-COT is an original Torex term for High Speed Transient Response. FEATURES APPLICATIONS Input Voltage Range : 2.5V5.5V Smart phones / Mobile phones Output Voltage Range : 0.8V3.6V (2.0%) Bluetooth Oscillation Frequency : 1.2MHz, 6.0MHz Output Current : 1A Portable game consoles Control Methods : HiSAT-COT Control Digital still cameras / Camcorders 100% Duty Cycle PWM Control (XC9257) Point-of-Load (POL) PWM/PFM Auto (XC9258) Wearable devices Protection Circuits : Thermal Shutdown Current Limit (Pendent character) Short Circuit Protection (Type B) Functions : Soft-Start UVLO C High Speed Discharge (Type B) L Capacitor :Ceramic Capacitor Operating Ambient Temperature :- 40 + 105 Packages :SOT-25, USP-6C Environmentally Friendly : EU RoHS Compliant, Pb Free TYPICAL APPLICATION CIRCUIT TYPICAL PERFORMANCE CHARACTERISTICS XC9257B18C/XC9258B18C L =LTF5022T-4R7N2R0(4.7H) C = 10F(GRM155R61A106M) C = 10F(GRM155R61A106M) IN L 100 V =3.7V IN 90 80 70 V =5.0V IN 60 50 V =3.7V V =5.0V IN IN 40 30 20 XC9258 10 XC9257 0 0.1 1 10 100 1000 Output Current: I (mA) OUT 1/30 Efficiency: EFFI (%) XC9257/XC9258 Series BLOCK DIAGRAM 1) XC9257/XC9258 Series Type A (SOT-25) 2) XC9257/XC9258 Series Type B (SOT-25) (*) The XC9257 offers a fixed PWM control, a Control Logic of PWM/PFM Selector is fixed at PWM internally. The XC9258 control scheme is a fixed PWM/PFM automatic switching, a Control Logic of PWM/PFM Selector is fixed at PWM/PFM automatic switching internally. Diodes inside the circuit are an ESD protection diode and a parasitic diode. 3) XC9257/XC9258 Series Type A (USP-6C) 4) XC9257/XC9258 Series Type B (USP-6C) Phase High Side Phase Short High Side CFB VIN CFB VIN Compensation Current Limit Compensation Protection Current Limit R1 R1 Error Amp. Error Amp. VOUT Comparator VOUT Comparator + + Synch. Synch. - - - S Q Buffer Lx - S Q Buffer Lx Logic Logic + + Driver Driver R2 R R2 R Vref with Vref with V SS VSS Soft Start Soft Start Minimum Minimum VSS VSS On Time VIN On Time VIN Generator Generator VOUT VOUT CE Control Logic, CE Control Logic, CE UVLO, CE UVLO, PWM/PFM PWM/PFM Thermal Shutdown Thermal Shutdown Selector Selector (*) The XC9257 offers a fixed PWM control, a Control Logic of PWM/PFM Selector is fixed at PWM internally. The XC9258 control scheme is a fixed PWM/PFM automatic switching, a Control Logic of PWM/PFM Selector is fixed at PWM/PFM automatic switching internally. Diodes inside the circuit are an ESD protection diode and a parasitic diode. 2/30