Temperature Protections
28
SLUUBD3D – September 2015 – Revised September 2018
Copyright © 2015–2018, Texas Instruments Incorporated
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