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I'm trying to make a boost converter that takes an input of 3.7V and outputs 5V. I found a chip that I think will work well, the LTC3872 by Linear Technology.

In the datasheet they give an example circuit which takes an input of 3.3V and has an output of 5V. However when I tried copying that exact circuit in LTSpice, it actually decreases the voltage. The resulting output voltage is 2.72 volts.

I've gone over the circuit several times and I can't seem to figure out any difference between the two so I'm thinking that there either is a problem with LTSpice or with the datasheet.

Is there something that I missed or am I doing something wrong?

For reference the datasheet can be found here: https://www.analog.com/media/en/technical-documentation/data-sheets/3872fc.pdf

Circuit from datasheet

LTSpice Simulation

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    \$\begingroup\$ I didn't check, but is there a minimum load requirement? Add a 1k resistor on the output. \$\endgroup\$
    – Transistor
    Commented May 2, 2020 at 18:00
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    \$\begingroup\$ In search box enter LTC3872 and next, click "Open this macromodel's test fixture". And bingo, you can run the simulation using LTC3872. Or right-click on the part "body" on the schematic you made and click "Open this macromodel's test fixture". \$\endgroup\$
    – G36
    Commented May 2, 2020 at 18:09

2 Answers 2

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I followed G36's suggestion and found a setting when I right clicked the module in LTSpice, and it appears that there was a different topology that they used that seems to work.

Functional Circuit

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What is the required gate voltage of the MOSFET you are using - a typical one will require more than 3.3v to turn-on.

You need to select an actual device and ensure that it can conduct the required current with 3.3v drive. I expect the data sheet has recommendations.

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