SLUS987C January 2011 – December 2019 BQ33100
PRODUCTION DATA.
The BQ33100 learning algorithm requires that the capacitors not be charged to their maximum charging value: for example, 2.5 V, under normal conditions. This enables the BQ33100 to charge the capacitors a small amount and then enable a discharge as part of the learning process. The value to which the capacitors must charge to is configured in V Learn Max and is expected to be the maximum charging voltage as specified by the capacitor manufacturer: for example, 2.5 V. This is typically also the V Chg MAX value, although some capacitor manufacturers will allow a higher voltage for the short learning period compared to the DC value it is held at during normal charging.
The nominal charging voltage must be selected to enable the capacitor array to provide the required amount of energy from the capacitance at that voltage. This data is available from the capacitor manufacturer's data sheet. The default value is 2.1 V per capacitor and as the device is configured as a 4-series system, then the programmed value in V Chg Nominal is 8400 mV.
V Chg A and V Chg B must be selected to be evenly spread between V Chg Nominal and V Chg Max: for example, V Chg A = 8900 mV (2.225 V per cap) and V Chg B = 9500 (2.375 V per cap).