SLUUC54C February 2020 – March 2024 BQ27Z558 , BQ27Z561 , BQ27Z561-R2
As described in Section 4.3, IT is not enabled by default. When the BQ27Z561-R2 gauge receives an enable request , the gauge is then in its learning cycle mode. It is not necessary to use the gauge in this mode for all gauges during manufacture.
This mode helps to determine the golden image, which can be programmed into all gauges during the manufacture process. Learning cycles are generally run under lab conditions. When the golden image is learned by a gauge, the gauge is left in the IT learned mode of operation. Thus, when its data flash image is transferred to another gauge during manufacture, that gauge is then in learned mode; the gauge with this update will still need to receive an IT enable request. Requiring this request prevents the gauge from any unintended updates that could result from pack activity during manufacture. It would be one of the last commands to the pack before it is prepared for shipment. For more details, see the application note Impedance Track™ Gas Gauge for Novices – bq20z70/z90 (SLUA397), which is can be downloaded from TI.com.