SMD SMPS Power Supply

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pasidu

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Dear All
Have a nice day

I am designing a Line follow robot which is included step up power supply to boost voltage from 6V to 12 ( DC to DC )

Reason to use Vboost to maintain constant voltage at line detection sensors and motor controller even battery voltage dropped

please advice about a chip that I can use to boost 6v to 12 volt and keep it constant even voltage reduced up to threshold level

It would be much appreciated if you can provided dedicated manufacture with sample circuit

it also appreciated any advice about this concept

Thanks in advanced
 

Thanks for the reply

Current 1.2A

No idea about duty of Frequency and need advice
 
Last edited:

Dear Klaus
Thanks for the info and I send the mail them to requesting info

I am going to use regulator output for Line sensor ( Five Ir photo trans receiver ) supply voltage as well as motor driver (TB6612FNG) supply voltage

What do you think about it , I mean same supply for inductive load and sensor
 

Hi,

I send the mail them to requesting info
Click to expand...
I wonder why sending a mail..all information is available..

If you are talking about a digital transceiver then I don't see a problem. Presumed a good PCB layout with proper GND planes.

Klaus
 

I had a store-bought line follower robot called Movit. It had two power supplies:
(a) 9V rectangular for sensor and control circuitry,
(b) two AA=3V for motors.

Evidently this was better than one supply. 3V was sufficient for the motors. They'd over-rev on a 9V supply. And the 9V battery would quickly deplete if it powered the motors.
 


Thanks for the reply

Could you please have a simplified schismatic diagram of it?

Thanks in advance

- - - Updated - - -

KlausST said:
Hi,

Presumed a good PCB layout with proper GND planes.

Klaus
Click to expand...

Dear Klaus
Can you please explain the GND plans that I need to consider at the design

Thanks in advance
 

Hi,

One solid copper layer of your PCB should be used as GND.
Don't use long wires for GND.

Klaus
 
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    pasidu

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KlausST said:
Hi,

One solid copper layer of your PCB should be used as GND.
Don't use long wires for GND.

Klaus
Click to expand...

Thanks for the reply

Please see the attached picture for the PCB that I am designing. As you can see I applied ground plane for bottom layer


Note

Is there any disadvantage if I apply both top and bottom layers as ground plane

Please advice
Thanks in advance
 

Hi,

in the picture I see a layer with wires and copper pour.
This is (hopefully) not your GND plane.

Klaus
 

KlausST said:
Hi,

in the picture I see a layer with wires and copper pour.
This is (hopefully) not your GND plane.

Klaus
Click to expand...

That is the GND plane

As per the picture The dark Green area is Ground and light Green are wires

So what is the wrong with it

Please advice
 

pasidu said:
Thanks for the reply

Could you please have a simplified schismatic diagram of it?
Click to expand...

The circuit itself was simple. The photosensor 'eyes' went to a comparator (or op amp configured as a comparator). Maybe there were 2 comparators.

If one sensor sees dark (detects a line), then it causes the op amp to turn on a transistor to one motor. When the other sensor sees dark, then the first motor shuts off and the other motor turns on. Only one motor spins at a time.

There was no loose play in the geartrain. The robot wiggled back and forth following the line.
 

Hi,

So what is the wrong with it
Click to expand...
It is not solid. Instead it is cut in pieces.
(Indeed, personally I'm no friend of copper pour as GND at all. It just pretends to be a solid plane, but it isn't)
And especially with switched power applications this may kill performance..
The pieces cause longer signal length...and this causes inductance..and combined with the switching frequency .. it causes impedance.
And this impedance can't be compensated with trace width (like copper pour). XL is about independent of trace width.

Therefore my recommendation: use one layer for GND only. No other signals in this layer.

Many switch mode IC manufacturers have good design guides and good application notes about how to design a good PCB layout.
I recommend to read through several different documents from different manufacturers.

Klaus
 
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    pasidu

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KlausST said:
Hi,

Therefore my recommendation: use one layer for GND only. No other signals in this layer.

Klaus
Click to expand...

Thanks for the reply
My main task of the PCB should not assign for switching. Since I am using two layer PCB it is impossible to reserve one layer for GND . However as per my design each layer has 75% of ground 25% signal lines ( Approximately )

My Question is
What should be the best design from the following two methods

1. Keep 75% of each layer as GND
2. Remove the 75% of GND layer ( Keep only tracks )

Please advice
Thanks in advance
 
Last edited:

Hi,

not easy to answer.

If you don´t have the knowledge on how to construct a good GND plane, then my recommendation is to use a true seperate layer for GND.
Maybe you need to go for a 4 layer PCB.

If you have the skills, then you may do this with a two layer PCB. It is more difficult than on a four layer PCB.
But if you have the skills, you had not asked...

--> either learn how to to construct good GND layers with embedded other signals, or use a four layer PCB.

But learning is a long time process. Expect some fails.
And one has to consdier a lot of factors. It´s not a simple task that can be learned within a froum thread.

In some threads I gave examples on how to do it. Starting with the member´s first approach .. and a couple of steps ... to my solution.
Device selection, parts placement, GND routing, signals routing, power supply routing, EMI considerations....
My solution means, that other PCB layouters will have other solutions. I assume it is not possible to generate the one and only optimum PCB layout.

Klaus
 
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    pasidu

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Movit robots!
In the early 1990s, I purchased one of those for my son, who was starting to display mechanical and electrical aptitudes. He loved it.
He later became a BSME and MSEE.

But to the OP's question, that is what I would also do. Separate batteries for the electronics and the motors. Helps to keep the noise and transients separate.
 
Dear schmitt

Thanks for you advice

One of my friend who have pololu 3pi robot which is running very perfectly but it is using single power supply for both motors and Sensors so I still confuse which method apply to my design

https://www.youtube.com/watch?v=mJV-KDqHgDQ&t=18s

Your further advice will be more beneficial to me

Thanks in advance
 

The optimal of course, is to have a single battery powering everything.

That battery voltage should be equal to the motor's requirements.
Why? Because the motors draw LOTS AND LOTS of power during acceleration, and even the most efficient PSU will waste significant amounts of power.

Then, use a MUCH SMALLER PSU to power the electronics.
 

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