need help starting buck boost mod

[WillyB]

I'm not sure about the diode. I've seen where a diode has been shown in-line with the atomizer to lower bottom end voltage range, but that also lowers the top end range. You won't want to do that since you're looking for maximum voltage output.

Sounds odd. The native minimum output voltage of the TI is 5V. A booster basically needs to boost, output voltage must be higher than input voltage... correct?

The diode will lower the entire range, the maximum can still be far higher than it needs to be.

 

[CraigHB]

Oops, sorry for that to the OP. You're right. The PTN04050C has output voltage up to 15V. I keep confusing it with other boosters that are typically limited to 5.5V. You gotta take my posts with a grain of salt. I make errors like that sometimes. I swear, sometimes I think I should just browse the forum quietly (easy on the agreement there Willy )

So yea, the diode will lower the bottom end, but since output voltage goes plenty higher than what you'd ever need, it's no problem. In that case, a diode in line will be advantageous. However, if you don't plan to go below 5V, it's better not to have it. Even a good Schottky diode will blow off almost a Watt at typical atomizer currents. A general purpose diode will blow off double that. 20% is a pretty big hit to efficiency.

 

[rusalka]

I don't care for the tantalums that much because they have the highest ESR which is something you want to minimize, but they're going to be cheaper than ceramic and smaller than electrolytic for the capacitance value you need. Not positive, but I think they work okay with the booster.

I went with mll ceramics capacitors, how do you tell the polarity on these thing. All they have is just the writing, no pos or neg symbols.

 

[CapeCAD]

I went with mll ceramics capacitors, how do you tell the polarity on these thing. All they have is just the writing, no pos or neg symbols.

There is no polarity with the ceramics, install either way.

 

[rusalka]

thanks capecad

 

[WillyB]

Well if space isn't an issue why not just use some caps right off TI's recommended list.

Dirt cheap too at 48¢

EEU-FC1E181 Panasonic Electronic Components Aluminum Electrolytic Capacitors - Leaded

 

[rusalka]

Space is the issue, unfortunately in this case. It is a tube mod.