I'm trying to make a constant current source of 2.1A which will operate around 1.7V.
I did some web searching, and I decided to use linear voltage regulators; simply put a adjusting resistor between the voltage outputs, and connect my load between the cathode and the ground:
- TPS757 constant current source with output voltage of 1.5V. Note that GND pin would be at 1.7V with respect to input ground terminal, which is response voltage of my load near 2A. This means there is 3.3V different between VIN and GND, as long as my load keeps constant voltage across.
However, I found that some regulators have GND pin, while others have ADJ pin; I believe that the output voltage indicated in data sheets refer to the voltage difference between OUT pins and either of those pins.
For those which has GND pins instead of ADJ pins, must I connect GND pin to the same ground of the input voltage? I've seen some examples with regulators with ADJ pins that had the ADJ pin voltage above the common ground voltage (ex LM317), but I'm not sure it would apply the same to regulators with GND pins.
If so, how would I make a constant current source out of them?
Thanks in advance!