Hi,
I'm designing a board that will require very accurate ADC conversions. I will be using the STM32F4 DSP chip with 12bit ADCs.
Now the chip itself is $17, and it comes in a demo board for $20 with on-board programmer. Since I am running out of space on my PCB anyway, I thought id just make use of the demo board and connect via header pins.
Only problem is, the Vref for the ADC is connected on the board to the Vdd pin (via RLC), and Vref is not broken out to the header. So I have decided to provide Vdd with the most accurate voltage possible.
The DSP chip needs about 150mA max, so I think 200mA is a good conservative figure.
Anyway, what is the best way to provide a precision 3V6 power source to Vdd? I have 15V and +-5V already on my PCB which can be used. Efficiency is not an issue, and to a certain extent circuit complexity.
There are plenty of LDO regs that have 1%, and I found a precision shunt reg that has 0.5% and 200mA (AP432A). Or should I build a circuit using a precision reference and a power buffer amp (such as the LT1010)? I'd really want to get the voltage as accurate as possible while keeping noise/ripple to a minimum.
Suggestions? I will consider downgrading to 3V3 too (more available) if the benefits are there.
Cheers