BQ4050 Datasheet, PDF (25/53 Pages) Texas Instruments – CEDV Gas Gauge and Protection Solution

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bq4050
SLUSC67A – MARCH 2016 – REVISED MARCH 2016
Feature Description (continued)
7.3.3 Charge Control Features
The bq4050 charge control features include:
• Supports JEITA temperature ranges. Reports charging voltage and charging current according to the active
temperature range
• Handles more complex charging profiles. Allows for splitting the standard temperature range into two sub-
ranges and allows for varying the charging current according to the cell voltage
• Reports the appropriate charging current needed for constant current charging and the appropriate charging
voltage needed for constant voltage charging to a smart charger using SMBus broadcasts
• Reduces the charge difference of the battery cells in fully charged state of the battery pack gradually using a
voltage-based cell balancing algorithm during charging. A voltage threshold can be set up for cell balancing to
be active. This prevents fully charged cells from overcharging and causing excessive degradation and also
increases the usable pack energy by preventing premature charge termination.
• Supports pre-charging/zero-volt charging
• Supports charge inhibit and charge suspend if battery pack temperature is out of temperature range
• Reports charging fault and also indicates charge status via charge and discharge alarms
7.3.4 Gas Gauging
The bq4050 uses the Compensated End of Discharge Voltage (CEDV) algorithm to measure and calculate the
available capacity in battery cells. The bq4050 accumulates a measure of charge and discharge currents,
estimates self-discharge of the battery, and adjusts the self-discharge estimation based on temperature. See the
bq4050 Technical Reference Manual (SLUUAQ3) for further details.
7.3.5 Configuration
7.3.5.1 Oscillator Function
The bq4050 fully integrates the system oscillators and does not require any external components to support this
feature.
7.3.5.2 System Present Operation
The bq4050 checks the PRES pin periodically (1 s). If PRES input is pulled to ground by the external system, the
bq4050 detects this as system present.
7.3.5.3 Emergency Shutdown
For battery maintenance, the emergency shutdown feature enables a push button action connecting the
SHUTDN pin to shutdown an embedded battery pack system before removing the battery. A high-to-low
transition of the SHUTDN pin signals the bq4050 to turn off the CHG and DSG FETs, disconnecting the power
from the system to safely remove the battery pack. The CHG and DSG FETs can be turned on again by another
high-to-low transition detected by the SHUTDN pin or when a data flash configurable timeout is reached.
7.3.5.4 1-Series, 2-Series, 3-Series, or 4-Series Cell Configuration
In a 1-series cell configuration, VC4 is shorted to VC, VC2, and VC1. In a 2-series cell configuration, VC4 is
shorted to VC3 and VC2. In a 3-series cell configuration, VC4 is shorted to VC3.
7.3.5.5 Cell Balancing
The device reduces the charge difference of the battery cells in a fully charged state of the battery pack by
gradually using a voltage-based cell balancing algorithm during charging. A voltage threshold can be set up for
cell balancing to be active. This prevents fully charged cells from overcharging and causing excessive
degradation and increases the usable pack energy by preventing premature charge termination.
Copyright © 2016, Texas Instruments Incorporated
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