Datasheet

LM5118, LM5118-Q1
www.ti.com SNVS566H –APRIL 2008–REVISED JANUARY 2014
HO Output
The LM5118 contains a high side, high current gate driver and associated high voltage level shift. This gate
driver circuit works in conjunction with an internal diode and an external bootstrap capacitor. A 0.1 µF ceramic
capacitor, connected with short traces between the HB pin and HS pin is recommended for most circuit
configurations. The size of the bootstrap capacitor depends on the gate charge of the external FET. During the
off time of the buck switch, the HS pin voltage is approximately –0.5 V and the bootstrap capacitor is charged
from VCC through the internal bootstrap diode. When operating with a high PWM duty cycle, the buck switch will
be forced off each cycle for 400ns to ensure that the bootstrap capacitor is recharged.
Thermal Protection
Internal Thermal Shutdown circuitry is provided to protect the integrated circuit in the event the maximum junction
temperature is exceeded. When activated, typically at 165°C, the controller is forced into a low power reset state,
disabling the output driver and the bias regulator. This protection is provided to prevent catastrophic failures from
accidental device overheating.
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