integrated circuit Improving absolute precision of ADC to balance battery voltage


Posted on Feb 5, 2014

Use a relatively high-end microcontroller ( Piccolo TMS320F28035, 12-bit resolution, +/- 4LSB offset, +/- 60 LSB gain ) to measure voltage across stacked battery cells and control associated analog electronics to equalize their charge. The microcontroller will also store data in an eeprom memory (blackbox). The current plan is to read up to 10 cell voltages.


integrated circuit Improving absolute precision of ADC to balance battery voltage
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The problem is the large common mode voltage (each cell can go up to 3. 5 V) - I cannot use isolated amplifiers such as INA124 or non-isolated high-precision INA117 due to high cost. Correct for the "high voltage-divider ratio" in software. You mentioned you have an EEPROM, store some calibration values in it. jippie Mar 31 `13 at 21:07 Have you considered to use one op-amp per cell to subtract the `common mode` voltage and possibly amplify the actual dV to make the best use of your ADC`s input range in one step Through the amplification you may even increase the accuracy of the measurement. Hanno Binder Apr 2 `13 at 21:40 @HannoBinder the dif opamps would have to have a very high MPRR ratio and voltage supply that exceeds the maximum / minimum input voltage, right SunnyBoyNY Apr 2 `13 at 21:47 Sorry, but what`s an "MPRR ratio" - Yes, the supply voltage must usually cover (at least) the absolute input voltage range. You can still use voltage deviders to reduce the input voltage (and then have it amplified by the amplifier again), or you maybe you can use the battery pack`s output itself as supply for the op-amps. Hanno Binder Apr 4 `13 at 7:58 @HannoBinder Sorry, I meant CMRR, not MPRR. I actually do like your suggestion - opamps with good (80dB+ CMRR) are quite common and the idea with lowering the cell voltage by a little bit using voltage dividers should work out as well. SunnyBoyNY Apr 4 `13 at 13:26 I`m not sure if...




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