SP6128A Low Voltage, Synchronous Step Down PWM Controller Ideal for 2A to 10A, Small Footprint, DC-DC Power Converters Optimized for Single Supply, 3V - 5.5V Applications GL 1 14 BST High Efficiency: Greater Than 95% Possible PV 2 13 GH CC 3 Discontinuous Startup for Precharged Output V 12 SWN CC SP6128A PGND 4 Accurate Fixed 300kHz Frequency Operation 11 ISET 14 pin TSSOP GND 5 Fast Transient Response 10 V FB COMP 6 NC Internal Soft Start Circuit 9 NC 7 NC Accurate 0.8V Reference Allows Low Output 8 Voltages Now Available in Lead Free Packaging Resistor Programmable Output Voltage Resistor Programmable Overcurrent Threshold APPLICATIONS Loss-less Current Limit with High Side R DS(ON) DSP Sensing Microprocessor Core Hiccup Mode Current Limit Protection I/O & Logic Dual N-Channel MOSFET Synchronous Driver Industrial Control Quiescent Current: 500A, 30A in Shutdown Distributed Power 14 pin TSSOP Low Voltage Power DESCRIPTION The SP6128A is a fixed frequency, voltage mode, synchronous PWM controller designed to work from a single 5V or 3.3V input supply, providing excellent AC and DC regulation for high efficiency power conversion. Requiring only few external components, the SP6128A pack- aged in an 14-pin TSSOP, is especially suited for low voltage applications where cost, small size and high efficiency are critical. The operating frequency is internally set to 300kHz, allowing small inductor values and minimizing PC board space. The SP6128A drives two N-channel power MOSFETs for improved efficiency and includes an accurate 0.8V reference for low output voltage applications. TYPICAL APPLICATION CIRCUIT 3V to 5.5V C5 C6 C7 10F 10F 10F D1 MBR0530 Q1 R3 FDS6690A 1 14 GL BST C4 8k R1 1F 5 2 13 SP6128A GH PV L1 1.0H CC 2.5V/10A 3 12 V CC SWN 4 11 PGND I SET D2 C8 C9 C10 C11 C1 5 10 GND V STPS2L25U FB 10F 10F 10F 470F 2.2F 6 9 Q2 NC COMP FDS6690A 7 8 NC NC R4 C12 1.7k 4.7nF C3 68pF R5 800 R2 7.87k C2 4.7n Rev. 08/19/05 SP6128A Low Voltage, Synchronous Step Down PWM Controller Copyright 2005 Sipex Corporation 1ABSOLUTE MAXIMUM RATINGS V PV ......................................................................................... 7V Junction Temperature, T ................................ 125C CC, CC J BST .................................................................. 13.2V Lead Temperature (Soldering, 10 sec) ............ 300C BST-SWN .............................................................. 7V ESD Rating............................................... 2kV HBM SWN ............................................................ -1V to 7V Thermal Resistance ............................. 31.7C/W JC GH ............................................... -0.3V to BST +0.3V GH-SWN ............................................................... 7V These are stress ratings only and functional operation All other pins ................................ -0.3V to V + 0.3V CC of the device at these ratings or any other above those Peak Output Current < 10s indicated in the operation sections of the specifications GH,GL .................................................................. 2A below is not implied. Exposure to absolute maximum Storage Temperature ........................ -65C to 150C rating conditions for extended periods of time may Power Dissipation .............................................. 1.3W affect reliability. ELECTRICAL CHARACTERISTICS Unless otherwise specified: -40C < T < 85C, 3.0V < PV = V < 5.5V, C = 22nF, CGH = CGL = 3.3nF, V = 0.8V, A CC CC COMP FB SWN = GND = 0V, typical value for design guideline only. PARAMETER MIN TYP MAX UNITS CONDITIONS QUIESCENT CURRENT V Supply Current 0.5 1.0 mA No Switching CC PV Supply Current 1 20 A No Switching, GH = Low CC V Supply Current(Disabled) 30 60 A COMP=0V CC PV Supply Current (Disabled) 1 20 A COMP=0V CC ERROR AMPLIFIER Error Amplifier Transconductance 0.6 ms COMP Sink Current 10 35 65 A V = 0.9V, COMP = 0.9V, No Faults FB COMP Source Current 10 35 65 A V = 0.7V, COMP = 2V FB COMP Output Impedance 3 M V Input Bias Current 130 nA FB Error Amplifier Reference 0.788 0.8 0.812 V Trimmed with Error Amp in Unity Gain OSCILLATOR & DELAY PATH Internal Oscillator Frequency 270 300 330 kHz Maximum Controlled Duty Cycle 90 % Loop in control - 100% DC Possible Minimum Duty Cycle 0 % Comp=0.7V Minimum GH Pulse Width 150 250 ns PV > 4.5V, Ramp up COMP voltage CC until GH starts switching CURRENT LIMIT I Pin Sink Current 10 12.5 15 A Temp = 25 C SET I Current Temperature Coefficient 3400 ppm/C SET Current Limit Time Constant 15 s Overcurrent Comparator 100 125 150 mV VI - V , Temp = 25C SET SWN Threshold Voltage Threshold Voltage Temperature 3400 ppm/C Coefficient Rev. 08/19/05 SP6128A Low Voltage, Synchronous Step Down PWM Controller Copyright 2005 Sipex Corporation 2