Hi,
I would be grateful for advice if what I'm doing is The Right Way or not... I'm not really good at doing analog electronics.
I'm building a simple power source based on small solar panel and supercapacitor. I want to be able to measure current that flows from the solar panel and current that flows from supercapacitor. Best if I was able to measure the current in wide range with highest possible accuracy.
For the design I'm using Cypress PSoC 4 chip (also to learn it/play with it), I want to use internal amplifiers. The priority is to keep the design simple and low-cost even at the cost of accuracy and/or wasted energy.
Here's the design I came up with:
There are two differential amplifiers with amplification 20k and 20 and a multiplexer for choosing the input. Two amplified outputs are fed to two differential inputs of SAR ADC (12 bits) with 1.024 Vref. I plan to use shunt resistor 0.1 Ohm. Designed ranges are 0.5 mA & 500 mA.
As far as my knowledge goes I'm suspecting that:
- Not-high-enough input impedance might falsify the amplified voltage.
- Design might need calibration or high precision resistors (what happens if the resistors are "asymetric"?).
- Problems with too high amplification?
Will this work? Any corrections or should I forget that's doable with the given requirements?
Thanks,
Lukasz.