High current boost voltage regulator selection for battery powered device.

[tightmopedman9]

I'm building a battery powered device which, at maximum, will consume 3A at 3.8V. I'd like to have the option to use 3-4 alkaline/NI-MH batteries or 2-4 lithium ion batteries. The first revision of my circuit used a buck regulator, however, the bootstrap voltage was set by a 5V LDO, meaning I had to have a Vin of at least 5V+.4V(dropout voltage). I've been looking at boost regulators, but am confused by their current ratings. Optimally, I'd like a package with external leads and Vin min of ~2.5V.

I've been looking at the MIC2253: **broken link removed**, unfortunately, it only comes in an MLF package. I'm confused by the current ratings; it says 'minimum 3.5A switch current'. Does this mean that the device won't output power unless the load is drawing 3.5A or more?

I've been searching everywhere and it seems like very few devices can offer such a high output current with such a low Vin.

 

[chuckey]

If you look at the graphs, they show an output current from zero upwards to 1 or 2 amps depending on Vin . I think the "minimum" should read "maximum"
Frank

 

[crutschow]

I know it's confusing but minimum means that, at a minimum (worst-case), it will output 3.5A. It could output more for an average device but it's only guaranteed for 3.5A.