A question mostly for Andrew and Tim,

I was preparing for a conference next week from TI and found that one of the 
topics to be covered is a particular Buck-Boost IC. After looking through the 
datasheet again, I would like to request a change from the linear LTC3441 that 
I was using for the Li-ion to Output Voltage supply.  In its place I would like 
to use the TI TPS63001 (3.3V) and or TI TPS63002 (5V). 

Links to both datasheets can be found near the top of  the captstone2009 HAP 
design page and also here:

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1042,C1116,C1790,P2149,D1054

http://focus.ti.com/lit/ds/symlink/tps63000.pdf

The parts are similar enough to make the change quickly as far as schematic 
capture goes, and the feedback circuit of the TI part is much easier to 
understand. I recognize this is a little (more like a lot) late in the game to 
be changing ICs, but the difficulty with compensation has me uncomfortable with 
my existing HAP design.

The main reason for choosing the linear IC in the first place was so that I 
could easily simulate it in LTSpice and see the design function in simulation 
before capturing the schematic in Eagle. However, the simulations I have run 
often disagree with the reference designs in the datasheet and as far as I am 
concerned they have not been helpful. This leads to the biggest issue I have 
with the LTC3441, I am still wrestling with the compensation after over a month 
of looking at it off and on. While I can use the reference designs as they 
stand, I would prefer to have a better understanding of the circuit that I am 
implementing. As such, I like the TPS6300X series, they are much easier to 
follow even with (or because of) a less thorough datasheet, the only immediate 
downside is that there may be a loss of efficiency (as low as 70% at some input 
voltages), though it's hard to say by comparing the datasheets. On the TPS6300X 
side, I have enrolled in the
 TI tech day conference on the 14th, and they will be covering the TPS6300x as 
it is used in single cell lithium ion battery products. So on the 14th, about 
the same time that the schematic capture needs to be finalized, I should have 
any remaining questions resolved.

Ken Z



      


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