I am runing a sensor (1.5mA), op amp lm/lmv/lpv358 (1/0.2/0.1mA) and =B5C (0.5mA) on two button cells
The batteries range from 4V to 6V. The sensor needs at least 4V. The =B5C can have at most 3.3V. The op amp is a sigma-delta A2D from sensor to =B5C.
So, I am thinking about a 4V zener to the sensor, minus diode drop to the =B5C.
Should I power the op amp before or after the diode? Also, 4V zener is hard to get. Should I use 5V plus two more diodes?
I have to commit to PCB in a few days, no time for more prototype/testing.