SP6669

SP6669 1.5MHZ, 600mA SYNCHRONOUS STEP DOWN CONVERTER FEATURES Up to 600mA Output Current Up to 95% Efficiency 1.5MHz Constant Frequency Operation Low Dropout Operation Mode: 100% Duty Cycle Output Voltages as low as 0.6V No Schottky Diode Required 200μA Quiescent Current (no load) Excellent Line and Load Transient Response Over-Temperature Protection 2.5V to 5.5V Input Voltage Range Lead Free SOT23-5 Package APPLICATIONS Cellular Phones Wireless Networking Digital Cameras Portable Media Players Bluetooth Devices Portable Instruments DESCRIPTION The SP6669 is a 600mA synchronous buck converter using a constant frequency current mode architecture with pulse width modulation (PWM) for low output voltage ripple and fixed frequency noise, a pulse skip mode (PSM) for light load efficiency and a LDO mode for 100% duty cycle. With a 2.5V to 5.5V input voltage range and a 1.5MHz switching frequency, the SP6669 allows the use of small surface mount inductors and capacitors ideal for battery powered portable applications. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. The SP6669 is available in an adjustable output voltage version, using an external resistor divider circuit, as well as fixed output voltage versions of 1.2V, 1.5V and 1.8V. The SP6669 is available in a 5 pin SOT-23 package. TYPICAL APPLICATION CIRCUIT Rev G – 12/02/2008 SP6669 1.5MHz 0.6A Sync. Step Down Converter © 2008 Exar Corporation 1/10 BLOCK DIAGRAM Fig.1: SP6669 Block Diagram PIN DESCRIPTION SOT23-5L Pin Number 1 2 3 4 Name EN GND SW VIN VFB Description Enable Pin. Do not leave the pin floating. VEN1.2V: Device enabled Ground Signal Pin. Switching node. Power Supply Pin. Must be decoupled to ground with a 4.7µF or greater ceramic capacitor. Adjustable Version Feedback Input Pin. Connect VFB to the center point of the resistor divider. Fixed Output Voltage Version, Output Voltage Pin. An internal resistive divider divides the output voltage down for comparison to the internal reference voltage. 5 VOUT Rev G – 12/02/2008 SP6669 1.5MHz 0.6A Sync. Step Down Converter © 2008 Exar Corporation 2/10 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground. Input Voltage VIN ..........................-0.3V to 6V EN VFB Voltage ............................ -0.3V to VIN SW Voltage.................... -0.3V to (VIN + 0.3V) PMOS Switch Source Current (DC) ........ 800mA NMOS Switch Sink Current (DC) ........... 800mA Peak Switch Sink and Source Current ....... 1.3A Operating Junction Temp. (Note 1)......... 125ºC Storage Temp. Range TSTG ....... -65ºC to 150ºC Lead Temperature (sold. 10s) TLEAD ........ 300ºC Thermal Resistance RθJA ............................................... 250ºC/W RθJC .................................................90ºC/W Note 1: TJ is a function of the ambient temperature TA and power dissipation PD (TJ= TA + PD x 250°C/W). Recommended Operating Conditions Operating Temperature TOP ....... -40ºC to 85 ºC Input voltage VIN......................... 2.5V to 5.5V VIN=3.6V, TA=25ºC, unless otherwise specified – Boldface characters apply over the full temperature range. Parameter Feedback Current Regulated Feedback Voltage Reference Voltage Line Regulation Output Voltage Accuracy Output Over-Voltage Lockout Output Voltage Line Regulation Peak Inductor Current Output Voltage Load Regulation Quiescent Current (Note 2) Shutdown Current Oscillator Frequency RDS(ON) of PMOS RDS(ON) of NMOS SW Leakage Enable Threshold Shutdown Threshold EN Leakage Current Symbol IVFB VFB ΔVFB ΔVOUT% ΔVOVL ΔVOUT IPK VLOADREG IQ ISHTDWN fosc RPFET RNFET ILSW VEN IEN VFB=0.5V or VOUT=90% VEN=0V, VIN=4.2V VFB=0.6V or VOUT=100% VFB=0V or VOUT=0V ISW=100mA ISW=100mA VEN=0V, VSW=0V or 5V, VIN=5V 0.4 ±1 1.2 ΔVOVL = VOVL – VFB (Adj.) ΔVOVL = VOVL – VOUT (Fixed) VIN=2.5V to 5.5V VIN=3V, VFB=0.5V or VOUT=90%, Duty cycle