Hello,
i developed a custom shield to being able to connect my sensors and LCD panel to the Arduino, instead of soldering the wire and simplifying the wiring.
The two sensors are powered by Arduino, the LCD display, a NEXTION 5", has a separate circuit, but I'm having problems on this one.
The AMS1117 gets too hot and (I assume) some sort of over temperature protection temporarily cutting off the power produced by the IC. In fact, after few seconds the display starts to turn on and off.
The schema is the following and was mutate from a common 5V stage present on each Arduino board:
I'm not a power supply guru, but your 1117 has got to get rid of around 7V. That likely comes out as heat and your regulator is entering thermal shutdown. How big was the heatsink pad on your custom shield?
The regulator will be dissipating ;
P = Vdrop x I
P= 12.4 x 0,320 = 3.96Watts
Look at the spec for the 1117 in that package,
Can you please post a schematic of your project.
It seems you have a schematic, but it is a disconnected net name type for designing PCBs.
This type is not good for trouble shooting, do you have a schematic with actual wire connections drawn so we don't have to go "search a word" over the document to find where everything is connected?
Without a heatsink or a minimal copper pad, the 1117 datasheet recommends a dissipation of "less than 1W".
This datasheet for a Nextion 5in display (don't know if its the same as the one you have) shows that the input voltage should be no more than 7V. With a 2V drop, the dissipated power would be much less at approximately 0.64W and well within the 1W limit.
It is unclear to me whether you are powering the Nextion display direct from 12.4V (you say its on a separate circuit), or via the regulator on your custom shield, and therefore which regulator is getting hot, but either way, the circuit is exceeding the thermal limits of the overheating regulator.
The higher the input voltage, the bigger the voltage drop and the greater the amount of heat that needs to be dissipated by the regulator.
The AMS1117 has a drop-out voltage of 1.3-1.5V so requires an input of at least 6.5V to maintain a 5V regulated supply at its output, but any more than that and the power is being wasted as heat. You either need to user a power supply with a lower voltage or use a DC to DC (buck) converter to reduce that 12.4V input to somewhere around 7V.
A fuller circuit diagram showing all the connections would indeed be more helpful.
Best to remove the linear regulator and substitute a tried and true, professionally designed switching regulator module, like this one or for 5V, this one.
