The utility model provides a drive circuit and a vehicle-mounted device, the vehicle-mounted device comprises a power supply, a
load circuit and a drive circuit, the drive circuit comprises a
comparator circuit, the
comparator circuit is used for generating PWM waveform; the input end of the bootstrap circuit is connected with the output end of the
comparator circuit, and the bootstrap circuit is used for charging according to the PWM waveform output by the comparator circuit and outputting a high-
voltage signal; the control end of the
transistor is connected with the output end of the bootstrap circuit, the first connecting end of the
transistor is used for being connected with a power supply, the second connecting end of the
transistor is used for being connected with a
load circuit, and the transistor is used for conducting the first connecting end and the second connecting end according to a high-
voltage signal output by the bootstrap circuit. According to the
driving circuit, on the basis of ensuring power supply to the
load circuit, more compact design
layout can be realized, dependence on an
integrated circuit (IC) can be eliminated, and the cost is reduced.