Super Cap - Buck/Boost Recommendations
khd00
Posts: 13
Morning:
I'm working on a small solar panel Super Cap charger for a remote monitoring project and I'm wondering if anyone has any high efficiency Buck/Boost regulator recommendations.
The panel I will be using will produce 5V open Circuit and about .75A short circuit and I'll be charging 2 - 2.7V 1500F super caps connected in parallel. Since the panel's real output will be close to the 2.7v +- I'm gonna need a buck/boost and I also want a regulator that I can use on both sides of the caps, charge and provide my regulated 3.3V out to power my circuit. Because I will be able take the caps to near 0V powering my circuit I am looking for something with as small as input V as I can get, 1.8 - 5.5 range or so but with enough heft to handle 500 - 750 mA needed to charge the caps.
Been looking at the TPS63030 from TI [noparse][[/noparse]http://www.ti.com/lit/gpn/tps63030] but its a screwy package so I thought I'd ask to see if there was anything else out there that someone has worked with that can accomplish this.
Appreciate any ideas.
Regards,
Kevin
I'm working on a small solar panel Super Cap charger for a remote monitoring project and I'm wondering if anyone has any high efficiency Buck/Boost regulator recommendations.
The panel I will be using will produce 5V open Circuit and about .75A short circuit and I'll be charging 2 - 2.7V 1500F super caps connected in parallel. Since the panel's real output will be close to the 2.7v +- I'm gonna need a buck/boost and I also want a regulator that I can use on both sides of the caps, charge and provide my regulated 3.3V out to power my circuit. Because I will be able take the caps to near 0V powering my circuit I am looking for something with as small as input V as I can get, 1.8 - 5.5 range or so but with enough heft to handle 500 - 750 mA needed to charge the caps.
Been looking at the TPS63030 from TI [noparse][[/noparse]http://www.ti.com/lit/gpn/tps63030] but its a screwy package so I thought I'd ask to see if there was anything else out there that someone has worked with that can accomplish this.
Appreciate any ideas.
Regards,
Kevin
Comments
Buck Boost and more..
Peter KG6LSE
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LOL
I went down a similar path with TI 63xxx.··In our case the·circuit was struggling - audibly·noisy which is never a good sign.· We had high peak·currents of about 2 amps, and that was part of the problem.· ·If you go this path pay lots of attention to the heatsinking and vias and high current paths, and you might get somewhere.· We chose to go·back to a simpler linear method, with a 6V solar panel (which puts out 6~13 volts unloaded DC) and a single FET to charge the 2 supercaps in series (to circa 3.6volts total), and prevent night discharge etc.· We also chose just to use larger supercaps, rather than going right down to 0 volts. This·was partly because we were not confident·about·the long term supercap parameters (C change·over·its lifetime; and C change·vs temperature) etc.
I can't really offer useful advice for the "other side" of the caps, other than to have something that has a very low quiescent current/shutdown mode.·· Also, depending on your application, consider a "separate" 3v3 supply just for the micro, the LTC3108 is good for at least 4 mA average current and has low Iq.·
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@Tubular: I hadn't considered noise yet as I am planning on having a separate power board to house these; charge and circuit power. My design goal was really to be as efficient as possible since the panel's specs are small and the caps are very large. Since the panel isn't built yet I could split it into two six cell groups and then go in series but I didn't want to waste the difference regulating down that much and I was avoiding the caps in series as I didn't want to mess with balancing as passive is wasteful and active is kinda complicated (at least for me). This is why I was hoping for an efficient Buck-Boost reg as my panel in parallel would produce +- 1V of the 2.7V needed which would really help the efficiency. I also was hoping to take advantage of the caps ability to be drained to zero without harm unlike batteries.
I was thinking of using an SX to manage both sides but it sounds like the noise might kill that idea.
Maybe I'll give the TI reg a try if I can find a breakout board and I can solder it unless anyone else has ideas or tells me I'm being too unrealistic here.
Thanks,
Kevin