TPS630252 parallel?

No, these are not designed to be paralleled.  How much current do you need, and at what Vin and Vout?

Thanks Chris.  I was afraid of that.  I need 3.3V and 3.5 Amps from a Li Ion battery (pack).   VIN = 4.2V to 2.7V.

That's a ton of power from a battery.  What's your load?  If possible, you could split it up into 2x 2A chunks.

Yes, I know its a lot of power from a battery.  It's 2 Li+ cells in parallel.  It's a portable, hand-held tester.  I need 10 Watts at 3.3 V worst-case.  Does TI have a good solution?

Other customers would connect their batteries in series to be able to use a higher voltage with less input current.  Then, the TPS62180 buck converter is an excellent fit and gives you 20W.

What does the 3.3V power?  GSM, RFPA, etc?

Thanks, yes I started out using 2 series batteries, but the universe of USB and AD Adaptors is very limited compared to single cell chargers.  I am using the TI BQ24167 charger.

The 3.3V supply powers our custom handheld tester.  It's used to power a few micros, a 5 inch LCD display, and an off-board data acquision system that requires as high as 8Watts at 3.3V.

I would think you could find a 12V adapter pretty easily.  The battery charger forum could help you find a good 2 cell charger from 12V.

Since your device is handheld, I would assume the operating temperature of our buck-boost IC would be rather low--certainly not 85 C.  Since the current limit decreases with temperature (see figure 1 in the D/S), you might be able to get 8W out from a single TPS630250 with this lower temperature.  Worst case is you wouldn't be able to discharge your batteries all the way down to 2.7V.  I'm not sure how much run time you would lose there.

Then, you could use a second TPS630250 or maybe a TPS63051 for the other loads.

Thanks Chris -

Looking at fig 1 is encouraging although it shows what the INPUT current is not OUTPUT, and efficiency isn't spec'd above 2 Amps that I can find.   But even so, I need 10 Watts worst-case at 3.3V = 3.0 Amps.  Assume efficiency at 3.0 A output current = 85%, then the input current is 3.6 Amps.  That seems marginally OK, assuming I can keep the IC below 85C.

What do you think?

I was suggesting to use two buck-boosts.  One fore the 8W and the other for the remaining power.

These devices use an input current limit, so with that you can compute what output current you get at all Vouts and Vins.  Page 13 of the D/S has more details.

I have decided to use two TPS630252.  I like to simplicity of just duplicating the design and they are more than capable for my needs.  

Thank you very much for your help.

Peter

TPS630252