Yes, the tinyX61 is more than enough for the job. TC1 actually is a stripped-down 3-channel Fast 10-bit Power Stage Controller with fault protection unit, dead time generator, etc. The ADC is adequately fast to monitor and regulate all the three output channels --even for an RGB LED solution, maybe.
You can also do the job by using the 8-pin t25/t45/t85 chip, whose TC1 is a single channel Fast 8-bit counter/timer, and its ADC also has a software selectable gain stage.
Using the internal 8 MHz internal RC oscillator clock (that will run slightly faster at 5.0V, since it is factory calibrated for use with Vcc=3.0V --but this can be easily corrected if needed) the AVR ADC can be running at (8MHz/32)/13.5 = 18.5 Ksps without any noticeable accuracy loss. The selectable ADC gain of 1x/8x/20x/32x can help reduce the LED current sensing shunt resistor value to a few tens of milliohms, making it possible to directly use a logic level MOSFET driven by a complementary emitter-follower stage gate driver (i.e. the 1.0A BC639/BC640 matched pair), and reading the FET source current by inserting the shunt resistor between the FET source and the ground.
You can also use both the buck or the buck-boost topologies. For the timing and the component calculations you can read the data sheets and application notes of HV9910, Kremmen suggested above.
The only problem I can see is the bloating, the use of high level programming languages (C++ or even C) will introduce, especially when CPU cycles counting becomes critical...
__________
Now, Greece should have never entered the Eurozone in the first place; just like Britain did or, more accurately, just like
[The Corporation of ]The City[ of London] did with
the help of the scumbag called George Soros, whose actions
justified Britain's (
The City's, actually) refusal to enter the Eurozone. That the Euro is a hard currency does not make it suitable to be the currency for any nation. For example, the Greek Drachma used to be one of the hardest currencies in the world until 1975, when the bankers begun shutting down sector by sector the Greek industry, and flooding steadily the country in debt since 1980:
Please note that during the ministry of Simitis, the debt did NOT decrease, as it seems it did at the chart above: This was the outcome of the "
creative accounting" trick PM Simitis pulled with the help of Goldman Sachs, in order to make Greece deceptively meet the requirements to join Eurozone.
What needs to be done (or, needed to have already been done) is Greece to renounce that Goldman Sachs loan as
Odious Debt; but to do that we need politicians of integrity and not the bankers' clowns our Parliament is infested with...
-George