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Ref design for LM21305 POL

Posted: 02 Nov 2011 ?? ?Print Version ?Bookmark and Share

Keywords:synchronous? buck? switching regulator?

National Semiconductor's LM21305 synchronous buck switching regulator boardmounted module is a DC-DC point-of-load (POL) solution capable of driving up to 5A of load current with conversion efficiency, output voltage accuracy, load and line regulation. The POL module can accept an input voltage between 3V and 18V and deliver an adjustable and accurate output voltage as low as 0.6V. The module has been designed to balance overall solution size with regulator efficiency while showcasing high current density. The power stage has been optimized for an input voltage of 12V and a switching frequency of 500kHz. While the output voltage setpoint is nominally 1.8V, it can be easily re-defined by modifying one of the feedback resistors. Moreover, by attaching a resistor between the TRIM pin and GND or VOUT, the output voltage can be adjusted up or down, respectively. For fast load transient response and stable operation over the entire input voltage range, the compenzation of the current-mode control loop has been designed to provide a loop bandwidth of 50kHz and phase margin of 60. The Enable (EN) and Power Good (PGOOD) pins can be applied to easily configure the LM21305 in power systems architected with multiple voltage rails and explicit sequencing requirements.

View the PDF document for more information.

Originally published by National Semiconductor at as "LM21305 POL Demonstration Module and Reference Design".

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