JAJSVE9 July 2024 BQ25820
PRODUCTION DATA
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To set the maximum input current using the ILIM_HIZ pin, a pull-down resistor to PGND is used. When using a 2-mΩ RAC_SNS resistor, the input current limit is controlled by: IAC_MAX = KILIM / RILIM_HIZ.
The actual input current limit is the lower value between ILIM_HIZ pin setting and register setting (IAC_DPM). For example, if the register setting is 20 A, and ILIM_HIZ pin has a 5-kΩ resistor (KILIM = 50 A-kΩ) to ground for 10 A, the actual input current limit is 10 A. ILIM_HIZ pin can be used to set the input current limit when EN_ILIM_HIZ_PIN bit is set to 1. The device regulates the pin at VREF_ILIM_HIZ. If pin voltage exceeds VREF_ILIM_HIZ, the device enters input current regulation. Entering input current regulation through the pin sets the IAC_DPM_STAT and FLAG bits, and produces an interrupt to host. The interrupt can be masked via the IAC_DPM_MASK bit.
The ILIM_HIZ pin can also be used to monitor input current. When not in input current regulation, the voltage on ILIM_HIZ pin (VILIM_HIZ) is proportional to the input current. Pin voltage can be used to monitor input current with the following relationship: IAC = KILIM x VILIM_HIZ / (RILIM_HIZ x VREF_ILIM_HIZ).
For example, if the pin is set with 5-kΩ resistor, and the pin voltage is 1.0 V, the actual input current is between 4.8 A to 5.2 A (based on KILIM specified).
If ILIM_HIZ pin is shorted, the input current limit is set by the IAC_DPM register. If hardware input current limit function is not needed, it is recommended to short this pin to GND. If ILIM_HIZ pin is pulled above VIH_ILIM_HIZ, the device enters HIZ mode (refer to Section 7.3.3.5). The ILIM_HIZ pin function can be disabled by setting the EN_ILIM_HIZ_PIN bit to 0. When the pin is disabled, input current limit and monitoring functions as well as HIZ mode control via the pin are not available.