BQ28Z560-R1 Datasheet, PDF (13/60 Pages) Texas Instruments – Single Cell Li-Ion Battery Gas Gauge and Protection

bq28z560-R1
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SLUSBD3 – APRIL 2013
Regardless of which sensor is used for measurement, a system processor can request the current battery
temperature by calling the Temperature() function. The temperature information is updated every 1 s in NORMAL
mode.
The bq28z560-R1 external temperature sensing is optimized with the use of a high accuracy negative
temperature coefficient (NTC) thermistor with R25 = 10 KΩ ± 1% and B25/85 = 3435 KΩ ± 1% (such as Semitec
103AT for measurement). REFERENCE SCHEMATIC shows additional circuit information on connecting this
thermistor to the bq28z560-R1.
OVERTEMPERATURE INDICATION
Overtemperature: Charge
If during charging Temperature() reaches the threshold of OT Chg for a period of OT Chg Time and
AverageCurrent() > Chg Current Threshold, then based on System Configuration the following occurs:
• If the GPIO is set for CFET control, the GPIO output will transition low and with the associated external
circuitry the CHG FET is turned OFF. When the temperature falls to OT Chg Recovery, the GPIO will
transition high again and allow the charge FET to turn on.
• If OT Chg Time = 0, the feature is completely disabled.
• If GPIO is configured as Alert output and if the OTC_EN bit in the Alert Configuration register is set to 1, the
Alert pin (Pin 12) will transition low to signify a fault has occurred. The polarity of the alert output can be
selected by setting the ALRT_POL bit in the Alert Configuration register. The fault is cleared on read.
Overtemperature: Discharge
If during discharging Temperature() reaches the threshold of OT Dsg for a period of OT Dsg Time, and
AverageCurrent() ≤ –Dsg Current Threshold, then based on system Configuration the following occurs:
• If the above condition is satisfied, then the Dsg FET is turned off. When the temperature falls to OT Dsg
Recovery, the Dsg FET is turned on.
• If OT Dsg Time = 0, the feature is completely disabled.
• If GPIO is configured as Alert output and if the OTD_EN bit in the Alert Configuration register is set to 1, the
Alert pin (Pin 12) will transition low to signify a fault has occurred. The polarity of the alert output can be
selected by setting the ALRT_POL bit in the Alert Configuration register. The fault is cleared on read.
PROTECTION
Overcharge Detector
When charging a battery, if the V_BAT voltage becomes greater than the overcharge detection voltage
(V_DET1 = 4.25 V typ) for a period up to the overcharge detection delay time (t_DET1 = 1.00 s typ), the bq28z560-R1
detects the overcharge state of the battery, and the COUT pin transitions to a low level. This prohibits charging
the battery by turning off the external charge control N-channel MOSFET.
In the overcharge state, if a charger is removed and a load is connected, the external charge control MOSFET
conducts the load current through its parasitic body diode. If the V_BAT voltage becomes lower than the
overcharge release voltage (V_REL1 = 4.07 V typ) for a period up to the overcharge release delay time
(t_REL1 = 8 ms typ), the COUT pin transitions to a high level, enabling charge of the battery by turning on the
external charge control N-channel MOSFET.
Over-Discharge Detector
When discharging a battery, if the V_BAT voltage becomes lower than the over-discharge detection voltage
(V_DET2 = 2.3 V typ) for a period up to the over-discharge detection delay time (t_DET2 = 24 ms typ), the bq28z560-
R1 detects the over-discharge state of the battery, and the DOUT pin transitions to a low level. This prohibits
discharging the battery by turning off the external discharge control N-channel MOSFET.
Copyright © 2013, Texas Instruments Incorporated
Product Folder Links: bq28z560-R1
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