Patent ID: 11936298
Assignee: ROHM CO., LTD.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 0:
1. A drive circuit, which is an N-channel or an NPN type high-side transistor drive circuit, comprising:
a level shift circuit, level-shifting an input signal to a signal that sets a voltage of a high-side power supply line to a high level and a voltage of a high-side ground line to a low level, wherein the level shift circuit includes:
a pulse generator, generating a first pulse that becomes high level for a certain period of time in response to a first edge of the input signal and a second pulse that becomes high level for a certain period of time in response to a second edge of the input signal;
an open drain circuit, in which a first output node becomes low level in response to the first pulse and a second output node becomes low level in response to the second pulse;
a first current mirror circuit, having an input node connected to the first output node of the open drain circuit, and folding back a first current flowing through the first output node of the open drain circuit;
a second current mirror circuit, having an input node connected to the second output node of the open drain circuit, and folding back a second current flowing through the second output node of the open drain circuit; and
a first latch circuit, which a state is changed in response to a third current that is an output of the first current mirror circuit, and a fourth current that is an output of the second current mirror circuit,

wherein the open drain circuit includes:
a first transistor, which is a high breakdown voltage element, having a gate receiving the first pulse and a drain connected to the first output node;
a second transistor, which is a high breakdown voltage element, having a gate receiving the second pulse and a drain connected to the second output node;
a third transistor, disposed between a source and a ground of the first transistor, and having a gate biased by constant voltage; and
a fourth transistor, disposed between a source and a ground of the second transistor, and having a gate biased by constant voltage,, wherein the first latch circuit includes a cross-coupled first inverter and a cross-coupled second inverter, and, wherein the third transistor and the fourth transistor having same or larger size as low-side transistors of the first inverter and the second inverter, respectively.