Datasheet

LM5008
SNVS280G –APRIL 2004–REVISED MARCH 2013 www.ti.com
During each off-time, the SW pin is at approximately 0V, and the bootstrap capacitor charges from Vcc through
the internal diode. The minimum OFF timer, set to 300ns, ensures a minimum time each cycle to recharge the
bootstrap capacitor.
An external re-circulating diode (D1) carries the inductor current after the internal Buck switch turns off. This
diode must be of the Ultra-fast or Schottky type to minimize turn-on losses and current over-shoot.
Thermal Protection
The LM5008 should be operated so the junction temperature does not exceed 125°C during normal operation.
An internal Thermal Shutdown circuit is provided to protect the LM5008 in the event of a higher than normal
junction temperature. When activated, typically at 165°C, the controller is forced into a low power reset state,
disabling the buck switch and the V
CC
regulator. This feature prevents catastrophic failures from accidental
device overheating. When the junction temperature reduces below 140°C (typical hysteresis = 25°C), the Vcc
regulator is enabled, and normal operation is resumed.
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