Part # LM2645 datasheet

Part Manufacturer: National Semiconductor

National Semiconductor

Part Description: LM2645 Advanced Two-Phase Switching Controller With Two Linear Outputs


Part Details:

LM2645 April 2005 Advanced LM2645Advanced Two-Phase Switching Controller With TwoLinear OutputsGeneral Description Features Two-Phase The LM2645 is a feature-rich IC that combines two current GENERAL mode synchronous buck regulator controllers, an adjustable n 4.5V to 30V input range linear regulator controller and a fixed 3.3V standby output n Power good function rail. n Input under-voltage lockout The two switching regulator controllers operate 180° out of n 10 µA Shutdown/Recycle for entire chip phase. This feature reduces the input ripple RMS current, n Thermal shutdown thereby significantly reducing the required input capacitance. Switching The two switching regulator outputs can also be paralleled to n TSSOP package operate as a dual-phase regulator. SWITCHING SECTION The use of synchronous rectification and pulse-skip opera- n Two synchronous buck regulators for fixed 5V/3.3V or tion at light load achieves high efficiency over a wide load adjustable outputs range. Fixed-frequency operation can be obtained by dis- n Outputs adjustable from 1.3V to 5.5V abling the pulse-skip mode. The switching frequency of the n 0.04% (typical) line and load regulation error LM2645 is user selectable between 200 kHz or 300 kHz. n Selectable switching frequency 200/300 kHz Controller The first switching controller (Channel 1) features a fixed 5V n Two channels operating 180° out of phase output, and the second switching controller controller (Chan- n Separate on/off for each channel nel 2) features a fixed 3.3V output. Both channels can also n Separate Power Good signals be independently adjusted from 1.3 to 5.5V. The adjustable n Current mode control with or without sense resistor linear regulator can be adjusted from 3.3V to 15V. An internal n Adjustable cycle-by-cycle current limit 5V rail is also available externally for driving bootstrap cir-cuitry. This rail also serves as the input for an internal LDO n Skip-mode operation available that provides the fixed 3.3V/50mA output rail. n Negative current limit W Current-mode feedback control assures excellent line and n Separate soft start for each channel ith load regulation and a wide loop bandwidth for excellent n Output UVP and OVP


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LM2645.pdf Datasheet