SWITCH DRIVE CIRCUIT
First Claim
1. A switch drive circuit which operates a load by alternately performing switching of a high-side switch placed in a high side and a low-side switch placed in a low side, the switch drive circuit comprising:
- a high-side power supply section which is a power supply for a high-side circuit;
a latch circuit which receives power supplied from the high-side power supply section and which latches a logical level of a high-side switching signal at the time of performing switching of the high-side switch;
a high-side driver which receives power supplied from the high-side power supply section and which drives the high-side switch by the high-side switching signal outputted from the latch circuit;
a low-side driver which receives power supplied from a power supply for a low-side circuit and which drives the low-side switch by a low-side switching signal; and
a high-side switch control circuit which sets, at the time of stopping the switching of the high-side switch, a stop established state in which the logical level of the high-side switching signal is fixed at a stop logic level needed for stopping the switching and which releases the stop established state at the time of performing the switching of the high-side switch,wherein;
the high-side switch control circuit includes a constant-current source which generates a reference current, a resistor, and a three-terminal switch;
an input end of the constant-current source and a first input end of the three-terminal switch are connected to a first potential side of the high-side power supply section and one end of the resistor is connected to a second potential side of the high-side power supply section;
another end of the resistor is connected to an output end of the constant-current source and a second input end of the three-terminal switch and an output end of the three-terminal switch is connected to an input end of the latch circuit; and
the stop established state is set or released in the latch circuit by cutting off or passing the reference current and controlling switching of the three-terminal switch.
1 Assignment
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Accused Products
Abstract
A switch drive circuit includes a high-side power supply section, a latch circuit, a high-side driver, a low-side driver, and a high-side switch control circuit. The latch circuit latches a logical level of a high-side switching signal at the time of performing switching of a high-side switch. The high-side driver drives the high-side switch by the high-side switching signal outputted from the latch circuit. The low-side driver drives a low-side switch by a low-side switching signal. The high-side switch control circuit sets, at the time of stopping the switching of the high-side switch, a stop established state in which the logical level of the high-side switching signal is fixed at a stop logic level, and releases the stop established state at the time of performing the switching of the high-side switch.
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Citations
13 Claims
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1. A switch drive circuit which operates a load by alternately performing switching of a high-side switch placed in a high side and a low-side switch placed in a low side, the switch drive circuit comprising:
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a high-side power supply section which is a power supply for a high-side circuit; a latch circuit which receives power supplied from the high-side power supply section and which latches a logical level of a high-side switching signal at the time of performing switching of the high-side switch; a high-side driver which receives power supplied from the high-side power supply section and which drives the high-side switch by the high-side switching signal outputted from the latch circuit; a low-side driver which receives power supplied from a power supply for a low-side circuit and which drives the low-side switch by a low-side switching signal; and a high-side switch control circuit which sets, at the time of stopping the switching of the high-side switch, a stop established state in which the logical level of the high-side switching signal is fixed at a stop logic level needed for stopping the switching and which releases the stop established state at the time of performing the switching of the high-side switch, wherein; the high-side switch control circuit includes a constant-current source which generates a reference current, a resistor, and a three-terminal switch; an input end of the constant-current source and a first input end of the three-terminal switch are connected to a first potential side of the high-side power supply section and one end of the resistor is connected to a second potential side of the high-side power supply section; another end of the resistor is connected to an output end of the constant-current source and a second input end of the three-terminal switch and an output end of the three-terminal switch is connected to an input end of the latch circuit; and the stop established state is set or released in the latch circuit by cutting off or passing the reference current and controlling switching of the three-terminal switch. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A switch drive circuit having a high-side switch located in a high side of the switch drive circuit and a low-side diode which is in a low side of the switch drive circuit, the low-side diode having a cathode located in a high-side switch side, the switch drive circuit operating a load by performing switching of the high-side switch, the switch drive circuit comprising:
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a high-side power supply section which is a power supply for a high-side circuit; a latch circuit which receives power supplied from the high-side power supply section and which latches a logical level of a high-side switching signal at a time of performing switching of the high-side switch; a high-side driver which receives power supplied from the high-side power supply section and which drives the high-side switch by the high-side switching signal outputted from the latch circuit; and a high-side switch control circuit configured to set, at a switching-stop time of the high-side switch, a stop established state in which a logical level of the high-side switching signal is fixed at a stop logic level needed for stopping the switching of the high-side switch, and configured to release the stop established state at the time of performing the switching of the high-side switch, wherein; the high-side switch control circuit includes a constant-current source which generates a reference current, a resistor, and a three-terminal switch; an input end of the constant-current source and a first input end of the three-terminal switch are connected to a first potential side of the high-side power supply section and one end of the resistor is connected to a second potential side of the high-side power supply section; another end of the resistor is connected to an output end of the constant-current source and a second input end of the three-terminal switch and an output end of the three-terminal switch is connected to an input end of the latch circuit; and the stop established state is set or released in the latch circuit by cutting off or passing the reference current and controlling switching of the three-terminal switch. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A switch circuit, comprising:
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a high-side switch configured to receive first current from a high-side power supply and output the first current to a load; a low-side switch configured to receive second current from a low-side power supply and output the second current to the load; and a switch drive circuit, comprising; a latch circuit configured to latch a logic level of a high-side switching control signal at a switching activation time, at which the high-side switch is activated to perform a switching operation; a low-side driver configured to drive the low-side switch with the second current based on a low-side switching signal; and a high-side switch control circuit configured to output the high-side switching control signal, such that the high-side switching signal is set to be a switching-stop logical state at a switching-stop time, and to be a switching-activation logical state at the switching activation time, wherein the high-side switch control circuit comprises; a constant-current source configured to generate a reference current; and
a three-terminal switch having a first terminal connected to a first terminal of the constant current source and a first terminal of the high-side power supply, having a second terminal connected to a second terminal of the constant current source and connected to output terminals of each of the high-side-switch and the low-side switch via at least one resistor, and having a third terminal connected to the latch circuit to supply the high-side switching control signal to the latch circuit.
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Specification