I have an application with an energy harvester (U_GEN) delivering in best case about 4.1 VDC. With this voltage a Supercap is charged; the SuperCap's voltage is then transformed by a DC/DC switcher TPS61099YFF to 3.5VDC (U_CAP). Both voltages are connected to a first wiring OR stage (double LM66100); this part of the electronics works well. The output delivers the expected voltage (U_GEN-CAP) which is connected to the input of a second Wiring OR stage (also double LM66100); here the voltage to compare comes from a coin cell CR2032 (max. 3.15V). The load at the output of the second stage is between 0.05...10 mA.
Now I see 2 problems:
1. When no battery is in place the voltage U_GEN-CAP is not fed to the output of the second Wiring OR stage (+U_F1)
2. When no harvester or SuperCap energy is available the battery voltage does not appear at the second Wiring OR stage (+U_F1)
I can't find the problem as the second stage is designed identical to the first one which works well. Do you have any idea? Are the pull-ups R5 / R12 correctly chosen?
Thanks in advance.