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[janice]

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[ronv]

I'm not quite sure what you are trying to accomplish.
Not all of the parts you listed can do 3 amps so the test may not be fair.
But a few ideas.
Test in both buck and boost mode for efficiency.
Cost per watt.
Circuit board size
Number of parts.

 

[janice]

Can you explain more on output current? can I say like less than 3A?
or If higher output current, is there any advantage?
Also, how can I find cost/watt, also number of parts?

 

[ronv]

Can you explain more on output current? can I say like less than 3A?
or If higher output current, is there any advantage?

In America more is almost always better. But seriously I would simplify the project. You have chosen 3 very different ICs so they would be used for different applications. So maybe you could choose only buck ICs from 3 suppliers rated at 1.5 amps at the voltages you want. Lets say 18 to 30 volts in and 12 volts out at 1 amp. Now you know you have 12 watts.

Also, how can I find cost/watt, also number of parts?

Usually you can find a typical schematic in the data sheet for the part. You can probably find most parts cost by searching a site like Mouser or Digikey

 

[janice]

I thought they are all the same, buck-boost controller.

Linear Technology Texas Instrument Rohm semiconductor
LTC3780 LM5118 BD9035AEFV-C

Why they are different ICs?
I need buck-boost controllers..

thanks!

 

[4pyros]

They all are buck-boost controllers and they are all different.
You only need to look at the datasheets to see that.
Have you looked at the data sheets?

 

[Misterbenn]

additional criteria that you might want to think about

• additional features, for example soft start, over temp cut-off, short circuit protection
• Tolerance, If I buy a thousand of these they will all have a different output voltage, what tolerance is acceptable
• Temperature range, which depends on the application. For example aerospace might be -40 +70
• Temperature stability, will the device tolerance go out of range within your temperature profile
• Voltage ripple, which is critical in audio or sensing applications
• switching frequency, Fixed? Variable? what Mhz? important for EMC compliance
• Transient stability, what happens if you suddenly apply or remove a load
• Efficiency, keeping in mind the advertised value is never what you achieve
• Discrete part count, some IC may be cheep but will require a lot of additional components offering a false economy compared to low component count solutions
• package availability, surface mount, through-hole?
• obsolescence, important in many industrial application as you'll still want spare parts 10-20 years down the line