I have a BQ25504EVM-674 Energy Harvesting Power Management with Battery Charging (EHM) development board by Texas Instruments. It fulfills my requirement of charging an energy store (e.g. supercap/rechargeable battery) and producing output voltage that can appropriately power a MCU (MSP430). The BQ25504 also has a boost converter, meant to be used with solar panels.
Most importantly for my design - It outputs a VBAT_OK (battery level) indicator that toggles high when the stored energy ramps up to 2.8V DC and toggles low when the energy store discharges and ramps down to 2.4V DC. Lets call these voltage thresholds V1 and V2 respectively.
As mentioned above, in the BQ25504EVM-674 by TI the V1 and V2 are fixed in the factory (V1=2.8V, V2=2.4V) by surface mount resistors on the board. If one needs to change these thresholds, then one has to de-solder the resistors and solder back appropriate resistors to get the required voltage levels. TI provides a spreadsheet to calculate the resistors, voltages etc.
However, I was wondering -
- is there another EHM which has similar functionality to the BQ25504EVM but with adjustable VBAT_OK voltage thresholds ?
- Or does anyone know how to change the resistor settings on the BQ25504EVM easily without desoldering ?