ZHCSJO3 May 2019 LMR34215-Q1
The LMR34215-Q1 incorporates an undervoltage-lockout feature on the output of the internal LDO (at the VCC pin). When VCC reaches 3.8 V (typ.), the device receives the EN signal and starts switching. When VCC falls below 3.3 V (typ.), the device shuts down, regardless of EN status. Because the LDO is in dropout during these transitions, the previously mentioned values roughly represent the input voltage levels during the transitions.
Thermal shutdown is provided to protect the regulator from excessive junction temperature. When the junction temperature reaches about 170°C, the device shuts down; re-start occurs when the temperature falls to about 158°C .