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LM3150

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SNVS561G – SEPTEMBER 2008 – REVISED SEPTEMBER 2015

Product Folder Links: LM3150

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Feature Description (continued)

8.3.7 Thermal Protection

The LM3150 controller should be operated such that the junction temperature does not exceed the maximum

operating junction temperature. An internal thermal shutdown circuit, which activates at 165°C (typical), takes the

controller to a low-power reset state by disabling the buck switch and the on-timer, and grounding the SS pin.

This feature helps prevent catastrophic failures from accidental device overheating. When the junction

temperature falls back below 150°C the SS pin is released and device operation resumes.

8.4 Device Functional Modes

The EN pin can be activated by either leaving the pin floating due to an internal pullup resistor to VIN or by

applying a logic high signal to the EN pin of 1.26 V or greater. The LM3150 controller can be remotely shut down

by taking the EN pin below 1.02 V. Low quiescent shutdown is achieved when VEN is less than 0.4 V. During

low quiescent shutdown the internal bias circuitry is turned off.

The LM3150 controller has certain fault conditions that can trigger shutdown, such as short circuit, undervoltage

lockout, or thermal shutdown. During shutdown, the soft-start capacitor is discharged. Once the fault condition is

removed, the soft-start capacitor begins charging, allowing the part to start-up in a controlled fashion. In

conditions where there may be an open drain connection to the EN pin, it may be necessary to add a 1-nF

bypass capacitor to this pin. This will help decouple noise from the EN pin and prevent false disabling.