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Application Notes

Quick Start Guide for a 0.5 Amp Buck Regulator Using The LM5574 and LM25574 (Rev. B)

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The LM5574 and LM25574 switching regulators feature all of the functions necessary to implement an efficient high voltage buck regulator using a minimum of external components. These easy to use regulators include either a 42V (LM25574) or a 75V (LM5574) N-Channel buck switch with an output current capability of 0.5 Amps. The operating frequency is programmable from 50kHz up to 1MHz. Protection features include: current limit, thermal shutdown and remote shutdown capability. The device is available in a TSSOP-16 package. This step-by-step guide provides an easy to use process to quickly select the external components necessary to complete a design. More detailed information including theory of operation, design trade-offs and additional application guidance is available in the device datasheet. Shown below in Figure 1 is a complete schematic for a 0.5 Amp step-down DC-DC converter. Several external component values can be standardized for most applications. The input voltage range, output voltage and desired operating frequency dictate the remaining component values.