Voltage drop at 5V output terminal on L298N

I’m powering two 5V DC motors via the L298N with 7V. At the same time I want to power my ESP32 from the 5V terminal on the L298N. My ESP32 needs a steady 5V to work but I’m experiencing voltage drops to 4.5V-ish when I power the motors. Specifically at the beginning of the acceleration.

The ESP32 is streaming a video and I’m controlling the motors over the network.

I’ve tried to but a capacitor(100mF, 25V) between the 5V terminal and the ESP32 but I couldn’t get it to work. I tested the capacitor with the Arduino Uno-s 5V pins and it works like a charm.

Does anyone have any suggestions on how to solve this issue?

Please post your circuit and datasheet or product-page links for all the hardware.

You realize the L298N doesn't output 5V, it requires it?

Do you mean 100mF capacitor or do you mean 100µF ? Thats a thousand-fold error if you mean the latter...

Motors:

ESP32:

L298N:

Here it says that I can use the 5V terminal to power my circuit if the voltage is under 12V:

https://www.google.com/amp/s/lastminuteengineers.com/l298n-dc-stepper-driver-arduino-tutorial/amp

And sorry, I meant 100µF not 100mF.

From ESP32 there are 4 wires going to the L298N IN terminal.

Here it says that I can use the 5V terminal to power my circuit if the voltage is under 12V:

Well yes, but they didn't mean ANY VOLTAGE UNDER 12 VOLTS !
GOOGLE "5V regulator headroom"

Of course there is nothing that says you have to use the regulator on the L298.
You can stick a TRACO dc 2 dc converter or an LDO on the board and use the
12V and GND from the onboard regulator for the add on LDO regulator.

A 7V input is TOO LOW !
The 5V regulator on the L298 is NOT an LDO regulator !
The TYPICAL HEADROOM for a 5V regulator is 3V, meaning you need a MINIMUM
of 8 volts, to get 5V out. It is a waste of time to persue trying to get 5V out with only
7V in. You might as well try to get water out of a rock.

1 Like

So if I add an LDO to the board and increase the voltage to 9V, will it work?

Well, not exactly.You are slightly confused.
The issue is that the L298 5V regulator is NOT
an LDO. If it WERE, the 7V would not be a problem. I believe the TRACO dc to dc converters
will work with only 7V but if not an LDO 5V regulator would work with only 7V input.

TRACO TSRN 1-2450

It's only when you DO NOT have an LDO that you
need to increase ine input to 8.5 to 9V.

REGULATOR HEADROOM

datasheet

The 7805 headroom is 2 to 3V , so the MINIMUM
INPUT VOLTAGE is 7.5 to 8V. The difference between 5V and what YOU are measuring TELLS YOU how far off you are. ("4.5 ISH") means your
roughly 500 to 700 mV (0.5V to 0.7V) low, so you
need to ADD THAT to the 7V you have, so you
need 7.7 to 8V MINIMUM INPUT VOLTAGE.
You can test an LDO or dc2dc converter with
7V and you MIGHT have to increase it to 7.5V
input and then just superglue the LDO onto
the L298 board. and run the wires to where
you need the 5V. We just added a TRACO 5V
regulator to a PCB that way at work.
Look at the datasheet. The input voltage range for the TRACO I linked is 6.5V.
This is indicative of an LDO although there is nothing on the datasheet that says it is an
LDO but you can do the math 6.5V-5V=1.5V HEADROOM (half that of an LM7805)
ALSO: READ Tom's post right after this one. The 5V pin is the Logic Power Input,
(IT'S NOT AN OUTPUT PIN) .
You can connect the output of the TRACO to that pin and REMOVE THE JUMPER ti DISCONNECT
the onboard LM7805.

Hi,


Note its say for the logic circuitry INSIDE the IC.

You provide 5V to this pin to SUPPLY POWER TO THE INTERNAL LOGIC OF THE L298N MODULE.

It is not for supplying the Arduino controller.
[soapbox]

78M05 Voltage regulator will be enabled only when the jumper is placed. When the power >supply is less than or equal to 12V, then the internal circuitry will be powered by the voltage >regulator and the 5V pin can be used as an output pin to power the microcontroller. The jumper >should not be placed when the power supply is greater than 12V and separate 5V should be >given through 5V terminal to power the internal circuitry.

Is the worst bit of information given, the on board LM7805 is not even bypassed as per the datasheet.

The only thing good about that "info sheet" is this;

Alternate Driver Modules: TMC2209, DRV8825, A4988, L9110S, DRV8711
[/soapbox]

They will be more efficient in your low voltage application.

Tom.... :smiley: :+1: :coffee: :australia: :astonished:

At the moment I don’t have an LDO but I can increase the voltage to 9V. Is it fine if I power the ESP32 from the 9V supply through a 5V voltage regulator?

If the ESP32 accepts 5V it doesn't care where it
came from.