how to limit (current/voltage) of l298n outputs?
hello,
I have been working on a beginners project , "controlling RC car with (pic microcontroller / bluetooth module / l298n dual H-bridge)"
the car works well .. if i drive only 1 motor, but when i decide that i will go forward and left/right, well the driving motor speed almost died even if there's no load on it , as well as the handelling motor , both motors r 6v , and i used 9v, 1A then 12v , 1A , even the car was working so good with its old controlling board .
so i wanna know if it's a power consumption problem , or the H-bridge .
even i doubt it's a power problem cause it was working fine with x4 1.5V batteries with its old board.
thx.
Discussions
Best Answer 3 years ago
The L298 has a current limit at 2 to 3 amps. Your can motors may be causing it to limit. See the data sheet
http://www.st.com/web/en/resource/technical/docume...
Answer 3 years ago
2~3 A is way more than what my motors need , they r simple dc motors like which u find @ kids toys , in case they r in free running mode (low load)each will be drawing around 0.2~0.4 A , the only case in which i might cross 2A is when it's @ stall mode,
and when i tested it was @ free running mode and yet the speed dies.
Answer 3 years ago
my handelling system is so stupid that keeps the motor on a stall mode which will consume so much current something around 1.5A .. i guess that's the problem.
thx for mentioning the limit it was very helpful :D
Answer 3 years ago
Good to hear.
Keep in mind the little 9 volt battery can only deliver 50ma for 18 minutes !
3 years ago
Sorry, just disregard my previous comment. I read two motors and assumed two separate H-bridge ICs not a dual one.
Start over please,
The RC worked OK with the old controller what was it an L297 ?
I suspect your inputs as a probable cause of the problem.
The PIC may not be putting enough signal voltage to the L298. Have you measured the the inputs voltage ?
The Low input needs zero to 1.5vdc and a HIGH input needs 2.3vdc to 5vdc.
Answer 3 years ago
inputs are fine low is 0 , high around 4.7v , and i connected enable pin to ccp (pwm) and it worked perfectly aswell, all r fine when its only 1 motor
Answer 3 years ago
Need to understand you measured the inputs r also fine with both motors ?
Can you still use the old controller to compare readings ?
Answer 3 years ago
all my reading r on 1 motor ,, pic input 4.7V high 0 volt low , l298n out around 7.8~8.2v when iam using 9v source.
when i use both motors ,, pic inputs r the same , l298n out drops to around 1.5~2v ,,
but i started to figure out the problem.
my handelling system is so stupid that keeps the motor on a stall mode which will consume so much current something around 1.5A .. i guess that's the problem
3 years ago
Better decoupling the Electronic Controls from each other by a DIODE and a large electrolytic 220uF Capacitor with a o.47 film Capacitor for each.
Answer 3 years ago
so it should be something like this i guess ?
if anything i need to add please notify me , and i will try it until i get ur answer.