JAJSS91 November 2023 BQ25756E
PRODUCTION DATA
The total input current is a function of the system supply current and the battery charging current. System current normally fluctuates as portions of the systems are powered up or down. Without DPM, the source must be able to supply the maximum system current and the maximum charger input current simultaneously. By using DPM, the battery charger reduces the charging current when the input current exceeds the input current limit set by the lower of IAC_DPM register bits, or ILIM_HIZ pin. This allows the current capability of the input source to be lowered, reducing system cost.
There are two thresholds to limit the input current (if both are enabled, the lower limit of these two will apply):
To set the maximum current using the IAC_DPM register bits, write to the IAC_DPM register bits. When using a 2-mΩ resistor, the input current limit range is from 1 A to 50 A with 125 mA/step. The default IAC_DPM is set to maximum code, allowing ILIM_HIZ pin to limit the current in hardware.
To set the maximum current using the ILIM_HIZ pin, refer to Section 8.3.5.1.1.1.
Although both limits are referenced to a 2-mΩ sense resistor, other values can also be used. A larger sense resistor provides a larger sense voltage and higher regulation accuracy, but at the expense of higher conduction loss. For example, using a 5-mΩ resistor yields programmability from 400 mA to 20 A with 50 mA/step.