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I am trying to use the TPS5403 (datasheet) buck converter to power an ESP32 at 3.3V from an input of 5-15V, however, I can't find enough resources online to be sure in my design.

Below, I have attached a circuit diagram.

  • VBUS is my 5-15V power source
  • GND is ground
  • 3v3 is my 3.3V output

Circuit Diagram Rev 2

Is this the correct way to wire the TPS5403?

How does one wire a buck converter using information purely from the datasheet?

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  • \$\begingroup\$ No, C2 is blocking the DC input. Vbus should go straight to pin 2 and C2 connects pin 2 to ground as per the "typical application" diagram on the datasheet. \$\endgroup\$
    – Finbarr
    Commented Aug 10, 2023 at 16:56
  • \$\begingroup\$ Does the updated version seem correct? \$\endgroup\$
    – OskarZyg
    Commented Aug 10, 2023 at 17:01
  • \$\begingroup\$ Is 100 nF enough input capacitance? \$\endgroup\$
    – winny
    Commented Aug 10, 2023 at 17:08

1 Answer 1

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Is this the correct way to wire the TPS5403?

Cin is likely too low, the datasheet specifies a minimum input capacitance of 10uF. Otherwise it looks good to me based off of the typical application circuit, I didn't dive into the rest of the datasheet though.

How does one wire a buck converter using information purely from the datasheet?

Generally follow the typical application circuit and the PCB layout sections of the datasheet. Read the detailed descriptions of each pin and the calculations needed for accompanying passives. Breadboard first when possible, that is useful for double checking and adjusting your passive values.

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    \$\begingroup\$ I think in this case (> 1 MHz switching frequency) breadboarding is probably not possible or at least not a good idea. \$\endgroup\$ Commented Aug 10, 2023 at 17:56
  • \$\begingroup\$ This chip is only available in SOIC package so breadboarding isn't really an option \$\endgroup\$
    – Finbarr
    Commented Aug 10, 2023 at 18:02
  • \$\begingroup\$ @user1850479 the ROSC resistor value would be setting a frequency of 0.75MHz I believe. Also I thought 10MHz was the threshold for breadboard frequencies? \$\endgroup\$
    – InBedded16
    Commented Aug 10, 2023 at 18:57
  • \$\begingroup\$ @Finbarr true, but not an impossible obstacle - I always keep SOIC-8 and SOT-23 breakout boards on hand for exactly this reason. \$\endgroup\$
    – InBedded16
    Commented Aug 10, 2023 at 18:58
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    \$\begingroup\$ @InBedded16 Switching frequency and bandwidth are different things. In this case since it's capable of MHz switching it's probably in the 100 MHz (or even more) bandwidth range. Just as a general rule you probably won't be able to breadboard a modern commercial switching converter since they're so fast and so sensitive to parasitics. \$\endgroup\$ Commented Aug 10, 2023 at 19:34

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