Electronics > Beginners

problem with boost converter

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MagicSmoker:

--- Quote from: alireza7 on July 29, 2019, 10:50:56 am ---
--- Quote from: krish2487 on July 29, 2019, 09:38:27 am ---It is starving the boost converter of the input voltage....

--- End quote ---

is there any way to protect a boost converter from being in such condition?

--- End quote ---

While it is true that inserting 100R in series with the boost converter will result in a huge voltage drop, this should only cause it to stop working, not blow up the switch. In addition, any converter IC intended for boost (or flyback/buck-boost) applications should limit the switch duty cycle to no more than 90-95% (though that really needs to be 80% or less, as these topologies are very unstable at high duty cycle). Consequently, it sounds like this controller IC is either terminally stupid or else the switch current limit function isn't being used or working properly.

alireza7:
After doing a lot of experiments I figured out in addition to 3x10uF output capacitors, there was a 220uF tantalum capacitor somewhere else in the secondary circuit. I removed that and the problem solved.

But I don't know why it cased TPS6102 burn. its datasheet said about minimum output capacitor but I didn't see anything about maximum output capacitor.

Why it is so?

mikerj:
The greater the output capacitance, the high the inrush current and the greater the voltage drop across your ammeter.  Did you build this circuit using a PCB using the recommended layout, or were you trying to use a breadboard?  Switching converters rarely work correctly on breadboards.

alireza7:

--- Quote from: mikerj on July 29, 2019, 05:14:44 pm ---The greater the output capacitance, the high the inrush current and the greater the voltage drop across your ammeter.  Did you build this circuit using a PCB using the recommended layout, or were you trying to use a breadboard?  Switching converters rarely work correctly on breadboards.

--- End quote ---

I used a PCB using the recommended layout.

alireza7:
Also, I found out even without ammeter and by just connecting the battery directly to the circuit this happens and IC burns if the output capacitor be large.

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