Alternate Voltage Buck Regulator

Semiconductor Integrated Circuits (ICs)
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Hello I have the following circuit for DC-DC step down conversion. The circuit calls out P/N LT3430IFE. I was wondering if I could get away with using P/N MAX16903SAUE50/V+T considering it looks like it just goes to a MIC3975 voltage regulator to be further lowered. Please tell me if I’m way off. And thanks in advance!

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Maybe @manchester49123,

Observations:

  • Not pin compatible.

  • The MAX has a lower output current switch, 1A vs 3A. This may or may not be important to your application.

  • Very different switching frequencies with LT at 200 kHz and MAX at 2.1 MHz. This requires different filtering networks and EMI considerations. Note that the MAX can operate spread-spectrum.

  • The MAX has an absolute max input rail of 42 VDC. Your design specifies 28 VDC leaving a reasonable overhead.

This preliminary view suggests you are in the neighborhood. However, you have you work cut out for you as there many more considerations as you move from the general idea to the specific implementation for your project.

As a side note, you may want to consider a Commercial Off-The-Shelf (COTS) DC to DC converter. Depending on the number of units you intend to manufacturer, you may be time and money ahead.

Sincerely,

Aaron

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Much appreciated! The MIC3975 steps the current down to 750 mA so I believe 1 A will be fine. COTS is not feasible due to limited space (will be in an enclosed panel).

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Best wishes as you complete your project, @manchester49123.

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