Boost converter design help!!!

[hemnath]

I have to step up 2.5V to 5V DC and output current max 50mA. So i've shipped LM2623 from TI. How to select external components like inductor, capacitor and some other discrete components? and what values should they be? and please help how to calculate. so that i can learn and use it for later design.

Thanks in advance

 

[keith1200rs]

If you go to ti.com there is the WEBENCH software on there which will do the design for you and give you the component values you need. Sometimes it doesn't work - instead saying there is no solution, in which case you need to do the calculations manually, but for 'normal' designs it works.

Keith

 

[hemnath]

ofcourse i have already tried it. But could not find the solution for lm2623.
I don't know how to calculate it manually. Thats why i have posted the thread. Please help!!!
If someone can help me how to calculate the values, it would be very helpful for me to learn and gain knowledge

 

[BradtheRad]

For one thing at 50 mA you do not need a large coil.

It is common to operate a switched coil at frequencies higher than our ears can hear. Say 20 kHz.

The coil is the center of action.

To clarify this concept, it helps to see an animated simulation.I have made an interactive simulation of a boost converter (using the animated simulator at falstad.com/circuit).

Click the link below to open the website, load my schematic, and run it on your computer. (Click Allow to load the Java applet.)

https://tinyurl.com/cvg4x7t

The supply is 2.5 VDC. The load is 100 ohms.

Click the switch at left to start the 'On' part of the cycle. Let up to see the 'Off' cycle.

Try to click it at a pace that maintains the load at your desired output volt level (5 V).

This is what a controller IC will do. Voltage regulation is another of its jobs.

The small resistance values represent the fact that there is some resistance in the components.

You can alter values at will. Right-click on a component to bring up an Edit window.