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I'd like to design a buck converter using MCP19035, I've gone through the datasheet of this component and and the design procedure using it. In the datasheet, it says that the component provides Two options for the frequencies (300kHz or 600kHz), but nothing says who to select one of two frequencies, which is a critical parameter for power train component selection. Can you please go through the datasheet and help me to understand this component ??

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  • \$\begingroup\$ luxina did you only want to know the part number or how to choose which frequency by design of "power train parts". Pls clarify. \$\endgroup\$ – Sunnyskyguy EE75 Apr 16 at 19:09
  • \$\begingroup\$ At first, I thought that the component provides the possibility to select the frequency by means of an external part, like UC18XX, which allow us to select frequency by selecting RT and CT, so I thought MCP19035 works the same way, but Ale chenski clarified that the frequency is selectable based on part order suffix MCP19035T-Axxx for 300kHz and MCP19035T Bxxx for 600kHz \$\endgroup\$ – luxina pado Apr 16 at 19:18
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For each particular chip the frequency is not selectable by any means. You have to order proper part, and design components based on your selection.

The frequency is selectable based on part order suffix, MCP19035T-Axxxx is for 300 kHz, and MCP19035T-Bxxxx is for 600 kHz, see page 41 of the datasheet.

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  • \$\begingroup\$ Yes, look at the section heading "PRODUCT IDENTIFICATION SYSTEM" on page 41 of 45. You just beat me to it. \$\endgroup\$ – vicatcu Apr 16 at 18:37
  • \$\begingroup\$ @SunnyskyguyEE75, the question is "to understand the design". The answer is that for each particular chip the frequency is not selectable by any means. You have to order proper part, and design components based on your selection. \$\endgroup\$ – Ale..chenski Apr 16 at 18:45
  • \$\begingroup\$ @SunnyskyguyEE75 "That's true for any part" - No some parts can be configured with a bias resistor or external capacitor or feedback filter selection to set the switching frequency. This part is factory configured. \$\endgroup\$ – Ale..chenski Apr 16 at 18:53
  • \$\begingroup\$ I think I understand my reading disability better, how to select \$\endgroup\$ – Sunnyskyguy EE75 Apr 16 at 20:09
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If the question is not how to select one of the two frequencies but rather why you would select one over the other the answer is as follows:

Lower switching frequency will have lower switching and AC losses (core, proximity, AC wire), and therefore higher efficiency. It will also mean a larger inductor for the same rippler current. It could possibly have lower EMI as well.

A higher switching frequency will typically allow a smaller solution size.

You should make the choice based on your design requirements.

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  • \$\begingroup\$ but in this case max DC current is the main reason. \$\endgroup\$ – Sunnyskyguy EE75 Apr 16 at 18:44

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