During operation, to protect the device from damage due to overheating, the junction temperature of the die is monitored.

In adapter mode, the TSHUT fault is triggered when T_J reaches T_{SHUT_RISING}, or T_{J_BUCK} reaches T_{SHUT_RISING_BUCK} if Buck is enabled, or T_{J_BB} reaches T_{SHUT_RISING_BB} if Buck-boost is enabled, or T_{J_LDO1} reaches T_{SHUT_RISING_LDO1} if LDO1 is enabled, or T_{J_LDO2} reaches T_{SHUT_RISING_LDO2} if LDO2 is enabled. In this case, the device stops charging, disables all the operating power rails, and then turns off input FETs and BATFET. After t_{TSHUT_DGLZ}, if T_J is below T_{SHUT_FALLING}, the input FETs and BATFET are turned on to power SYS and charging can be restarted. The integrated power rails are reenabled when TSHUT fault recovers. The power-up sequence is implemented if power sequence is used with V_SYS>V_{SEQ_UVLOZ}.

In battery mode with ADC disabled (ADC_EN = 0), the TSHUT fault is triggered when T_{J_BUCK} reaches T_{SHUT_RISING_BUCK} if Buck is enabled, or T_{J_BB} reaches T_{SHUT_RISING_BB} if Buck-boost is enabled, or T_{J_LDO1} reaches T_{SHUT_RISING_LDO1} if LDO1 is enabled, or T_{J_LDO2} reaches T_{SHUT_RISING_LDO2} if LDO2 is enabled. In this case, the device disables all the operating power rails. After t_{TSHUT_DGLZ}, the BATFET is turned on to power SYS. The integrated power rails are reenabled when TSHUT fault recovers. The power-up sequence is implemented if power sequence is used with V_SYS>V_{SEQ_UVLOZ}.

In battery only mode with ADC disabled (ADC_EN = 1), the TSHUT fault is triggered when T_J reaches T_{SHUT_RISING} , or T_{J_BUCK} reaches T_{SHUT_RISING_BUCK} if Buck is enabled, or T_{J_BB} reaches T_{SHUT_RISING_BB} if Buck-boost is enabled, or T_{J_LDO1} reaches T_{SHUT_RISING_LDO1} if LDO1 is enabled, or T_{J_LDO2} reaches T_{SHUT_RISING_LDO2} if LDO2 is enabled. In this case, the device disables all the operating power rails, and then turns off the BATFET. After t_{TSHUT_DGLZ}, if T_J is below T_{SHUT_FALLING}, the BATFET is turned on to power SYS. The integrated power rails are reenabled when TSHUT fault recovers. The power-up sequence is implemented if power sequence is used with V_SYS>V_{SEQ_UVLOZ}.

The Buck thermal shutdown protection is not active in PFM mode and LDO1/LDO2 thermal shutdown is not active with load less than 1 mA.

When TSHUT fault is triggered, TSHUT_STAT/TSHUT_FLAG is set to 1 with interrupt signal sent from INT pin if TSHUT_MASK is not set to 1.

If TSHUT_LOCKOUT_EN is set to 1, the device is locked out in TSHUT protection (input FETs off, BATFET off, rails disabled) if TSHUT fault is triggered 7 to 13 times in the 2s window. Once the device is locked out in TSHUT protection, VIN needs to be toggled to bring the device out of the lock-out state after t_{TSHUT_DGLZ}. After t_{TSHUT_DGLZ}, if T_J is below T_{SHUT_FALLING}, the input FETs or BATFET are able to be turned on to power SYS and charging can be restarted. The integrated power rails are reenabled when TSHUT fault recovers. The power-up sequence is implemented if power sequence is used with V_SYS>V_{SEQ_UVLOZ}.

When LDO1 is in always on mode (LDO1_EN_SET = b111) and LDO1_SHIP_AO is set to 1, the LDO1 is disabled only when T_J T_J reaches T_{SHUT_RISING_LOD1} and resumes operation when T_J falls below T_{SHUT_FALLING_LOD1}. In LDO1-ON Ship mode, TSHUT_STAT/TSHUT_FLAG is not updated if the fault is triggered.

During the charging process, to prevent overheating in the device, the device monitors the junction temperature of the die and reduces the charging current once T_J reaches the thermal regulation threshold (T_REG) based on bits set by THERM_REG setting. If the charge current is reduced to 0, the battery supplies the current needed to supply the SYS output. Thermal regulation can be disabled through I²C.

Four temperature settings are selectable in I²C and shown in Section 7.6.

The die junction temperature, T_J, can be estimated based on the expected board performance using the following equation:

T_J = T_A + θ_JA * P_DISS

The θ_JA is largely driven by the board layout. For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics Application Report.

For reliable operation, limit the junction temperature to the maximum listed in the Recommended Operating Conditions table. Operation above this maximum temperature causes the device to exceed operational specifications. Although the thermal protection of the device is designed to protect against overheat conditions, it is not intended to replace proper heat sinking. Continuously running the device into thermal shutdown or above the maximum recommended junction temperature reduces long-term reliability.