ZHCSN83A june 2020 – january 2021 BQ25731
PRODUCTION DATA
Usually adapter can supply current higher than DC rating for a few milliseconds to tens of milliseconds. The charger employs two-level input current limit, or peak power mode, to fully utilize the overloading capability. The level 1 current limit, or ILIM1, is the same as adapter DC current, set in IIN_DPM register. The level 2 overloading current, or ILIM2, is set in ILIM2_VTH, as a percentage of ILIM1.
When the charger detects input current surge and battery discharge due to load transient (both the adapter and battery support the system together), the charger will first apply ILIM2 for TOVLD (PKPWR_TOVLD_DEG register bits), and then ILIM1 for up to TMAX – TOVLD time. TMAX is programmed in PKPWR_TMAX register bits. After TMAX, if the load is still high, another peak power cycle starts. Charging is disabled during TMAX and TOVLD already expires; once TMAX, expires, a new cycle starts and resumes charging automatically.
To prepare entering peak power follow below steps:
Host need to set EN_PKPWR_IIN_DPM=1b to enable peak power mode triggered by input current overshoot. The overshoot threshold is IIN_DPM register which is same as the level 1 current limit (ILIM1). Typical application waveform refer to Figure 10-18.