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Here is my circuit enter image description here

For some reason my 3.3v regulator is over heating. The regulator is a TLV1117LV33. I've tried everything to try and debug the problem but can't seem to figure out what's wrong except maybe a short to ground somewhere on my board.

I've connected just a MicroUSB cable to the regulator and even that is causing it to overheat.

Could it be because of the capacitors I have on there?

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    \$\begingroup\$ Did you measure 3V3 to GND to check whether there is a short or not? What is the actual output voltage? \$\endgroup\$
    – Wesley Lee
    Commented Sep 17, 2020 at 21:10
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    \$\begingroup\$ Double check the pinout of the regulator. \$\endgroup\$
    – td127
    Commented Sep 17, 2020 at 21:17
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    \$\begingroup\$ ”except maybe a short to ground somewhere on my board” This should be your first suspect. \$\endgroup\$
    – winny
    Commented Sep 17, 2020 at 21:18
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    \$\begingroup\$ What is Vcc? If you are expecting the regulator to do a lot then it will get hot. \$\endgroup\$
    – Solar Mike
    Commented Sep 17, 2020 at 21:26
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    \$\begingroup\$ You said your regulator is TLV1117LV33. Your schematic doesn't match its pinout. Pin 1 should be ground, pin 2 (and tab) is output, pin 3 is input. \$\endgroup\$
    – td127
    Commented Sep 17, 2020 at 21:55

2 Answers 2

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As @td127 pointed out , the pinout is non standard. See annotated diagram below.

LDO block diagram

With LDO's the series pass element is a PNP bipolar or PMOS transistor, both of these are grown from P type substrate, and the substrate is connected to the tab (the block of silicon inside the device has it's back face soldered to the tab , for heat dissipation). If you look at PNP and PMOS power transistors, the collector (drain) is always connected to the substrate. The LDO is just a PNP or PMOS transistor, with some extra circuitry attached to the base (gate).

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@td127 was correct. I mismatched my voltage regulator with my footprint.... Double check your work before having PCBs made..

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  • \$\begingroup\$ First clue. Does LED come on? No. Odds are regulator is not regulating! \$\endgroup\$
    – StainlessSteelRat
    Commented Sep 17, 2020 at 22:24

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