I looked at the datasheet TPS62742. It says that there is a required input DC voltage and it looks like an output voltage is produced but it says "sw" which I thought was where the switching signal should be connected to. Is the switching signal somehow produced internally to the model or does it need to be produced externally by a microcontroller?
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2 Answers
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Please read the datasheet for this device.
The "SW" pin connects to the switching inductor. The datasheet provides this information, along with all the other information needed to use this chip.
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\$\begingroup\$ The data sheet also provides reference designs. @the_circuit \$\endgroup\$– RussellHCommented Jul 4 at 21:28
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\$\begingroup\$ I reviewed it. There isn't much detail about the switching signal but it looks like it is produced by a comparator. \$\endgroup\$ Commented Jul 5 at 0:02
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The SW node is a power output, not a signal input. It's the node that gets switched by the switching transistors and/or diode. It's where you attach the inductor and, if applicable, the bootstrap capacitor. Trying to do anything else with it would cause the entire system to not work; it's crucial to the operation of the converter.
At the same time, some converter ICs (though not this one) can accept an external frequency input. The pin that does this is usually labelled SYNC, or, if combined with other functions, MODE/SYNC or EN/SYNC. I've never seen one, however, that requires a frequency input; the SYNC signal is specifically for synchronizing multiple converters to run at the same frequency with a known phase relationship. It can also be used with a single converter and a spread-spectrum frequency generator to use spread-spectrum switching.
