I'm a little late with my school project.
I have only 1 week left and I'm stuck at the layout of my board...
My problem is that I'm using a standalone ATMega 328P-AU TQFP and
I need to control 2 motors in series.
Motor Specs:
Stall 2A@3V
I need to drive these motors from 6V up to 8.4V.
I have already measured the true RMS value and got around 5A @ 8.6V.
I know it is a little bit critical for this chip (TLE 5206-2) the chip will be fused though.
I'm a little bit concerned, the datasheet states, that I need to have 2 PWM pins to change the diraction.
Datasheet:
Sign/Magnitude Control
For this mode two ports with PWM capability are necessary. Motor turns clockwise
(current flows from OUT1 to OUT2; means: OUT1 is switched HIGH continuously and
OUT2 is PWM controlled.
To achieve motor counter clockwise turning change input signals to:
IN1 = PWM; IN2 = H.
did they say that because(Example):
IN1 = PWM(80%); IN2 = H /Motor = 80%speed, clockwise
IN2 = PWM(80%); IN1 = H /Motor = 20%speed, counter-clockwise
Or is something important behind that, so that it wouldn't work?!?
Block-Diagram shows 2x the same bridge in the chip...
Can I use the chip this way:
IN21 = PWM; IN2 = H/L /clockwise+counterclockwise
Besides that, What kind of a heatsink do I need, how can I callculate the size of it?!?
I bought a few of those very recently for use in a model railway controller. Because they are new to me I did not recognize the number - sorry. I have not yet used them but I have every confidence that they will do what I want.
I particularly chose them because they have a fault indication and short-circuit protection. The application I plan to use them in is unlikely to draw more than 1 amp unless there is a short circuit.
For direction control you need to hold 1 input pin LOW and apply PWM to the other. For the other direction swap. In other words it needs two PWM pins on the Arduino but only one is active at any one time.
You could use external logic ICs (AND gates?) to steer a single PWM signal to the different inputs on the driver.
But why is that so? I mena the block diagram of the chip shows 2x the identical half-bridge, why can't I just use one pin as PWM and the other one to set the direction? I have also found a circuit in the Internet which makes me confused.
Either the guy who drew the circuit did something wrong or the guys who made that datasheet are not pointing the pwm input clearly out...
That is really bad, I have only a PWM and a normal I/O pin left on my layout...
there is now way I can add more to that board (no space left).
And before I connect the PWM to one input and a normal I/O to the other input, I want to make sure that it works and I don't end up with magic smoke in my presentation...
Yes, I know that I can use analog pins assnormal I/O lanes my problem is, that I have only one I/O pin and one PWM pin left... And I dont have space for other components to shift he PWM from one input of the driver to the other one... An other problem is, that it has to be through hole because the back side of my PCB is full of SMD parts which are covered by a heatsink so I'm not able to use a SMD part anymore... And I've checked other parts, but there is nothing suitable for my project
(5.5V->8.5V Input, 5A RMS Brushed DC Fullbridge)
long story short
1x I/O +1x PWM
5A RMS min
Fullbridge
5.5->8.5V
Through hole
as small as possible
No other components to shift the PWM from one input of the driver to an other...
Yup I did, but there is no more space on the PCB to put some other circuitry on it...
And I can't change it because it took me about 3 month to design this damn pcb
