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I want to make a -12V supply and I came across a circuit using LM2576 that match my requirement but I am not confident enough about its working.

There is a note in the datasheet page no-16, Application and implementation section saying: Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

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Form the functional block diagram, I understand the connection of the feedback pin, but in the buck-boost configuration in the upper image, the feedback pin is connected to the ground, and I want to know why? Please help me understand the working of the buck-boost circuit shown in the above figure. enter image description here

Datasheet: https://www.ti.com/lit/ds/symlink/lm2576.pdf?ts=1609223000480&ref_url=https%253A%252F%252Fwww.google.com%252F

winny
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Manish
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    The feedback is a trick to make an otherwise positive regulator provide negative output voltage by simply changing what you regard as reference voltage. True negative regulators with feedback referenced against ground do exist if you search around. Have you tried to simulate it, or read application notes for (inverting) buck-boost converters in general to understand how they work? – winny Dec 29 '20 at 13:55
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    The device's ground is connected to the output of the circuit (-12V). So as far as the device is concerned that is it's reference point and the feedback pin is at +12V – Unimportant Dec 29 '20 at 13:55
  • I couldn't find any tool to simulate this, there is no spice model I guess. They are using the adjustable type, so why would they give 12V as feedback? – Manish Dec 29 '20 at 14:29
  • D1 prevents a negative output in lower Schema – Tony Stewart EE75 Dec 29 '20 at 15:20

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