Thermal shutdown limits total power dissipation by turning off the internal switches when the IC junction temperature exceeds 168°C (typical). Thermal shutdown does not trigger below 158°C. After thermal shutdown occurs, hysteresis prevents the device from switching until the junction temperature drops to approximately 159°C. When the junction temperature falls below 159°C (typical), the LM6x4xx-Q1 attempts to soft start.

While the LM6x4xx-Q1 is shut down due to high junction temperature, power continues to be provided to VCC. To prevent overheating from a short circuit applied to VCC, the LDO providing power to VCC has reduced current limit while the part is disabled due to high junction temperature. The LDO only provides a few milliamperes during thermal shutdown.