Our team is designing a digital hearing aid for a school project that will be rechargeable via a micro USB cable. The BQ2000 battery charger IC is being used to implement this but we are coming across some battery charging issues. This chip is located in the bottom right section of the attached schematic. I made the connections by following the examples found in the datasheet. The +5 V is the USB power supply.
We are using a single cell NiMH battery which has a battery voltage of 1.2 V. The intended charge time is 90 minutes. After taking some measurements of the battery voltage when connected to the circuit, we found out that the battery voltage did not increase at all. Interestingly, the battery voltage did increase when it was disconnected from the circuit possibly due to the battery's chemistry? I am not sure why it does that.
The other part of the schematic is the boost converter that will boost the voltage from 1.2 V to 1.8 V to power the digital signal controller on the other circuit.
Does this schematic show a correct configuration for battery charging? I was unsure of how the MOD pin should have been hooked up.
Thanks!