PSU choice for Micro project

[Wp100]

Hi,

Have an ESP32 micro project thats used to control various output including some 12Vdc devices like a fan, linear actuator and led strip lights.

We have a generic AC adapter, the block shaped type, not a wall plug in, rated at 12v dc 3A which will easily handle the load of those devices, average below 1 A , odd peaks around 2A

However we need 5V for the Micro and some of the low current input devices plus a tft display, and trying to decide which is the best method.
3V3 devices will use the ESPs regulated supply.

We could use a typical LM2596 module or a LM7805 but wonder if they are likely to be affected too much by the mosfet switching or noise of the 12V devices or is there any extra circuity on these 5v regulators we can add to help isolate / negate that ? eg larger 5v rail caps

Another option would be to introduce a totally separate psu like a HiLink Mains to 5V module, but is that overkill ?

thanks.

 

[MaxHeadRoom78]

Using the 7805 use the recommended filter caps re spec sheet, and should be OK.

 

[For The Popcorn]

Using the 7805 use the recommended filter caps re spec sheet, and should be OK.

Dropping 12v to 5v to power an ESP32 and TFT display may not be such a trival matter. According to one source an ESP32 can draw 240mA, with peaks to 790mA.

Say the average load is 500mA at 5 volts. The voltage regulator would be dissipating (12 – 5) × 0.5 = 3.5 watts. Not cool, so to speak.

 

[Wp100]

Dropping 12v to 5v to power an ESP32 and TFT display may not be such a trival matter. According to one source an ESP32 can draw 240mA, with peaks to 790mA.

Say the average load is 500mA at 5 volts. The voltage regulator would be dissipating (12 – 5) × 0.5 = 3.5 watts. Not cool, so to speak.

Should have qualified things better, the ESP is not using wifi mode so will not be drawing the heavy currents you mention.
When running the sensors and tft screen its using 120ma and even allowing for output optos etc the load will probably never exceed 200ma.

However you raise a good point as we may want to use wifi at some future point and as you say the peaks can get nearer to 1A though believe the average is rather lower.
There are quiet a few variants of 7805 that can handle 1.5A or 2A rather than the usual 1A. eg 7805CV 78S05CV

 

[For The Popcorn]

There are quiet a few variants of 7805 that can handle 1.5A or 2A rather than the usual 1A. eg 7805CV 78S05CV

.... with adequate heat sinking.

 

[Pommie]

I'd use a switching 5V regulator (LM2596 type) and feed the ESP via the 5V pin and let it use it's own (LDO) 3.3V regulator.

Mike.
Edit, sounds like that was your original plan.