SP6123/SP6123A Low Voltage, Synchronous Step-Down PWM Controller Ideal for 2A to 10A, Small Footprint, DC-DC Power Converters FEATURES Optimized for Single Supply, 3V - 5.5V Applications BST GL 1 8 High Efficiency: Greater Than 95% Possible SP6123 GH V 2 7 CC 8 Pin nSOIC Accurate Fixed 300kHz (SP6123) or 500kHz 3 GND 6 SWN (SP6123A) Frequency Operation 5 V COMP 4 FB Fast Transient Response Internal Soft Start Circuit Now Available in Lead Free Packaging Accurate 0.8V Reference Allows Low Output Voltages APPLICATIONS Resistor Programmable Output Voltage DSP Loss-less Current Limit with High Side R DS(ON) Microprocessor Core Sensing I/O & Logic Hiccup Mode Current Limit Protection Industrial Control Dual N-Channel MOSFET Synchronous Driver Distributed Power Quiescent Current: 500A, 30A in Shutdown 8-Pin Surface Mount Package Low Voltage Power DESCRIPTION The SP6123 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 SP6123 pack- aged in an 8-pin NSOIC, is especially suited for low voltage applications where cost, small size and high efficiency are critical. The operating frequency is internally set to 300kHz (SP6123) or 500kHz (SP6123A), allowing small inductor values and minimizing PC board space. The SP6123 drives an all N-channel synchronous power MOSFET stage for improved efficiency and includes an accurate 0.8V reference for low output voltage applications. TYPICAL APPLICATION CIRCUIT 3V to 5.5V IN MBR0530 C IN V IN CBST GL BST 680F 1F 0.8V to 5.0V 2A to 10A CB GH FDS6890A V CC (1.6V, 4A shown) 2.2F SP6123A L1 SWN GND V OUT 1.5H COMP V FB R1 10k RZ C C C OUT3 15k OUT1 OUT2 CP 1F 470F 470F 56pF CC 4.7nF FDS6890A R2 10k STPS2L25U Date: 9/13/04 SP6123 Low Voltage, Synchronous Step Down PWM Controller Copyright 2004 Sipex Corporation 1ABSOLUTE MAXIMUM RATINGS 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 rating conditions for extended periods of time may Storage Temperature ........................ -65C to 150C affect reliability. Power Dissipation V ....................................................................................................... 7V CC Lead Temperature (Soldering, 10 sec) ............ 300C BST .................................................................. 13.2V ESD Rating............................................... 2kV HBM BST-SWN .............................................................. 7V ELECTRICAL CHARACTERISTICS Unless otherwise specified: 0C < T < 70C, 3.0V < V < 5.5V, C = 22nF, CGH = CGL = 3.3nF, V = 0.8V, A 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 V Supply Current (Disabled) 30 60 A COMP = 0V CC ERROR AMPLIFIER Error Amplifier Transconductance 0.6 mS COMP Sink Current 15 35 60 AV = 0.9V, COMP = 0.9V, No Faults FB COMP Source Current 15 35 60 AV = 0.7V, COMP = 2V FB COMP Output Impedance 3 M V Input Bias Current 100 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 SP6123 Internal Oscillator Frequency 450 500 550 kHz SP6123A Max. Controlled Duty Cycle 90 93 % Minimum Duty Cycle 0 % Comp=0.7V Minimum GH Pulse Width 100 250 ns V > 4.5V, Ramp up COMP voltage until CC GH starts switching CURRENT LIMIT Internal Current Limit Threshold 160 200 240 mV V - V Temp = 25 C CC SWN V - V > 2.5V BST CC Current Limit Threshold 0.34 %/C Temperature Coefficient Current Limit Time Constant 15 us SOFT START, SHUTDOWN, UVLO Internal Soft Start Slew Rate SP6123A 0.2 0.60 0.95 V/ms SP6123 0.1 0.3 0.6 V/ms COMP Discharge Current 185 A COMP = 0.5V, Fault Initiated COMP Clamp Voltage 0.55 0.65 0.75 V V = 0.9V FB COMP Clamp Current 10 30 65 A COMP = 0.5V, V = 0.9V FB Shutdown Threshold Voltage 0.29 0.34 0.39 V Measured at COMP Pin Shutdown Input Pull-up Current 2 5 10 A COMP = 0.2V, Measured at COMP pin V Start Threshold 2.63 2.8 2.95 V CC V Stop Threshold 2.47 2.7 2.9 V CC Date: 9/13/04 SP6123 Low Voltage, Synchronous Step Down PWM Controller Copyright 2004 Sipex Corporation 2