How to correctly connect/wire up a IC

[retro]

Hello Guys

I'm new to electronics and I need some advise on how to correctly connect/wire up a IC.

I've just bought a LM2825-ADJ 1A DC-DC buck converter. Which pins do I connect a potentiometer (regulates output voltage) and black and red power wires to?



https://www.electro-tech-online.com/custompdfs/2008/02/LM2825.pdf

 

[retro]

**broken link removed**

This is what the IC's pin config looks like. Plz help as I don't want to fry this thing.

 

[dknguyen]

It's all in the datasheet (like always). Try reading it under Application Information. Make sure you don't mistake the test circuits for the application circuits.

 

[retro]

It's all in the datasheet (like always). Try reading it under Application Information. Make sure you don't mistake the test circuits for the application circuits.

Do I connect the negative power line to GND at pin 1 and then out again on pin 2 to the load? I assume that the positive line is connected in to a input pin 16-20 and out again of pin 4-8 output pin and from their to the load.

Pin 10 is for the potentiometer. Do I connect the potentiometers positive line this and it's negative to to a GND pin?

Please correct me if I'm going wrong.

 

[dknguyen]

THe potentiometer when used as a voltage adjuster probably has one end connected to both a positive voltage and the other end to ground (or the corresponding negative voltage, but probably ground) and the wiper connects to the adjustment pin so that it acts as a variable resistive divider. Which power pins I do not know, but from lookina at the adjust pin input voltage on page 3, it appears that the two voltages the potentiometer ends connect between is the input voltage and ground.

The pad layout on page 11 should help you. THe converter doesn't seem to be isolated (isolated means that the output ground does not have to be the same as input ground) which means they should be connected for best reliability. Even if it's isolated, you can get rid of the isolation by also connecting input/output grounds together.

 

[blueroomelectronics]

Nice IC, but at $32 not cheap.
There is a PCB layout at the back of the datasheet, just hook it up like the layout.
Input is all pins from 16-21, output all pins from 4-8, and GND any pin labeled GND. You must use ALL the pins for in, out & gnd.
You'll also need a couple of caps as shown in the schematic at the end.

 

[retro]

Do I connect the black negative 12v power source line to the IC's GND or is this a circuit ground of 0V?

The potentiometer has three legs. Ground, wiper and the output from the wiper.

If I understand correctly I connect the first leg to the IC's GND. The second leg the wiper to the IC's to pin 10 and the third leg to the red positive power line before it connect to the IC's input connection.

 

[retro]

attachments

 

[retro]

I guess that I will have to work it out my self.

 

[Diver300]

Two things.

Firstly, the potenentiometer would be connected like this.

Wiper - pin 10
one end - ground
other end - ouput of the regulator

Secondly, that is not a good way of doing the voltage adjustment. It will be very non-linear, and you can also get large output voltages.

The better way is to use the circuit on page 7 of the data sheet, and make R2 a variable resistor. R1 is fixed. That way the adjustment goes from 1.23V up to whatever maximum you want (using the formula on that page) and it will be linear.

To use a potentiometer as a variable resistor, just connect to the wiper and one end. If the voltage goes up when you turn it down, connect to the other end instead.

 

[HerbertMunch]

Nice IC, but at $32 not cheap.

Why $32?

**broken link removed**

 

[retro]

This is a photo of how far I've gotten.

I bridged and soldered together the IC's pins as directed by the PCB layout.

The orrange wire comes from the IC's GND back plate.
The brown line just to the left of the IC holder is the output.
The white line to the right of the IC holder is the input.

I have connected the potenentiometers wiper (red wire) to the IC's ADJ pin No. 10

The two input caps in parallel at the top are currently isolated from the rest of the circuit.

Where do I connect the input +, - power lines to?

 

[retro]

Diver300

Do I need to connect a resistor, R1 in to the potentiometers R2 GND connection? How to I work out the value of the resistor to use? The IC that I'm using is the (LM2825H-ADJ) version which has been optimised to produce 7V to 15V.

 

[john1]

Hi,

A view of the other side too please.

John

 

[Diver300]

What voltage range are you looking for?

What is the resistance of the potentiometer you are using?

As you are using the potentiometer as a variable resistor, there are only two connections that should be made to it.

 

[retro]

What voltage range are you looking for?

What is the resistance of the potentiometer you are using?

As you are using the potentiometer as a variable resistor, there are only two connections that should be made to it.

Hello Diver

I am looking to obtain 12 Volts. The maximum resistance value of the potentiometer is 9.88KΩ and minimum is 0.02KΩ.

Do I need to connect another resistor to the potentiometer?

I have two wires already connected to the potentiometer. A red wire that connected to the wiper. I have connected this wire to the IC's ADJ pin No 10. I also have a black wire connected to one of the potentiometers output legs. However I'm unsure where I need to connect this wire to.

 

[retro]

Plz help

 

[blueroomelectronics]

What voltage are you supplying it with?

 

[retro]

What voltage are you supplying it with?

The supply is variable since I'm using a 8W 500mA solar panel which outputs up to 18v. However I need to regulate this to around 12v.

I assume that connect the positive power wire to the IC's input connector and the potentiometer output leg to the IC's output connector. I'm not sure where I connect the negtive power wire or the IC's ground to though.

 

[blueroomelectronics]

Well it's a buck converter, it'll only give you 12V out if the input is greater than 12V. A buck/boost converter will work with a input lower than its output.
The pot is wired as follows: GND, wiper to ADJ, OUTPUT
Why didn't you just buy the 12V version of the IC?