Texas Instruments bq78350-R1 Technical Reference

Temperature Protections www.ti.com
28
SLUUBD3D–September 2015–Revised September 2018
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Protections
Status Condition Action
Normal AFESysStat() [OVRD_ALERT] = 0 SafetyAlert()[AFE_OVRD] = 0
Alert AFESysStat() [OVRD_ALERT] = 1 SafetyAlert()[AFE_OVRD] = 1
Trip
AFESysStat() [OVRD_ALERT] = 1 for AFE
External Override Delay duration
SafetyAlert()[AFE_OVRD] = 0
SafetyStatus()[AFE_OVRD] = 1
OperationStatus()[XCHG, XDSG] = 1
All FETs turn OFF
Recovery
AFESysStat() [OVRD_ALERT] = 0 for AFE
External Override Recovery duration
SafetyAlert()[AFE_OVRD] = 0
SafetyStatus()[AFE_OVRD] = 0
OperationStatus()[XCHG, XDSG] = 0
CHG and DSG FETs allowed to turn ON
3.7 Temperature Protections
The device provides overtemperature and undertemperature protections based on cell temperature
measurements. The cell temperature based protections are further divided into a protection-in-charging
direction and discharging directions. This section describes in detail each of the protection functions.
For temperature reporting, the device supports a maximum of either three external thermistors or three
internal temperature sensors. The selection of Internal or External temperature sensors is set by
Settings:Temperature Enable[SOURCE]. Unused temperature sensors should be disabled by clearing
the corresponding flag in Settings:Temperature Enable[TS3][TS2][TS1].
The Temperature() command returns the cell temperature measurement. The MAC and extended
command DAStatus2() also returns the temperature measurement from the enabled temperature sensors
and the cell temperature.
The cell temperature based overtemperature and undertemperature safety provide protections in charge
and discharge conditions. The battery pack is considered in CHARGE mode when Battery[DSG] = 0,
where Current() > Chg Current Threshold. The overtemperature and undertemperature in charging
protections are active in this mode. The Battery[DSG] is set to 1 in a NON-CHARGE mode condition,
which includes RELAX and DISCHARGE modes. The overtemperature and undertemperature in
discharge protections are active in these two modes.
3.7.1 Overtemperature in Charge Protection
The device has an overtemperature protection for cells under charge.
Status Condition Action
Normal
Cell Temperature in Temperatures() <
OTC:Threshold OR not charging
SafetyAlert()[OTC] = 0
Alert
Cell Temperature in Temperatures() ≥
OTC:Threshold AND charging
SafetyAlert()[OTC] = 1
BatteryStatus()[TCA] = 1
Trip
Cell Temperature in Temperatures() ≥
OTC:Threshold AND charging for OTC:Delay
duration
SafetyAlert()[OTC] = 0
SafetyStatus()[OTC] = 1
BatteryStatus()[OTA] = 1
BatteryStatus()[TCA] = 0
OperationStatus()[XCHG] = 1
Charging disabled if FET Options[OTFET] = 1
Recovery
SafetyStatus()[OTC] AND Cell Temperature in
Temperatures() ≤ OTC:Recovery
SafetyStatus()[OTC] = 0
BatteryStatus()[OTA] = 0
BatteryStatus()[TCA] = 0
OperationStatus()[XCHG] = 0
Charging is allowed if FET Options[OTFET] = 1.
Class Subclass Name Type Min Max Default Unit
Protections OTC Threshold I2 –400 1500 550 0.1°C
Protections OTC Delay U1 0 255 2 s
Protections OTC Recovery I2 –400 1500 500 0.1°C

Texas Instruments bq78350-R1 Specifications

General

Brand	Texas Instruments
Model	bq78350-R1
Category	Controller
Language	English