Driving circuit for stepping motor
AssigneeRohm Co., Ltd.
InventorHiroki Sugamoto
Life of this patent
Estimating the term…
Abstract
A direction setting pin DIR receives a direction signal ROT that indicates the rotational direction of the stepping motor. A clock pin CLK receives a clock signal CLK that indicates the rotational direction of the stepping motor. A logic circuit generates a first internal signal and a second internal signal that respectively indicate the states of the first H-bridge circuit and the second H-bridge circuit according to the direction signal ROT and the clock signal CLK. When the clock signal CLK remains in a predetermined state for a predetermined judgment time, the logic circuit transits to a predetermined mode.
Claims11
A driving circuit for a stepping motor comprising a first coil and a second coil, the driving circuit comprising:
- a first H-bridge circuit to be coupled to the first coil;
- a second H-bridge circuit to be coupled to the second coil;
- a direction setting pin to be coupled to receive a direction signal that specifies a rotational direction of the stepping motor;
- a clock pin to be coupled to receive a clock signal that indicates a rotational operation of the stepping motor;
- a logic circuit structured to generate a first internal signal and a second internal signal indicative of respective states of the first H-bridge circuit and the second H-bridge circuit according to the direction signal and the clock signal;
- a first pre-driver structured to drive the first H-bridge circuit according to the first internal signal;
- and
- a second pre-driver structured to drive the second H-bridge circuit according to the second internal signal, wherein, when the clock signal remains in a predetermined state for a predetermined judgment time, the logic circuit transits to a predetermined mode;
- wherein the predetermined mode is a weak excitation mode,
- and wherein, in the weak excitation mode, the first internal signal and the second internal signal are generated such that an output of the first H-bridge circuit and an output of the second H-bridge circuit are each reduced as compared with a corresponding output current in a normal excitation mode.
A control method for a stepping motor comprising a first coil and a second coil, the control method comprising:
- providing a first H-bridge circuit coupled to the first coil;
- providing a second H-bridge circuit coupled to the second coil;
- generating, by means of a processor, a clock signal so as to rotationally drive the stepping motor;
- generating, by means of the processor, a direction signal that indicates a rotational direction of the stepping motor;
- switching a state of the first H-bridge circuit and a state of the second H-bridge circuit according to the direction signal and the clock signal;
- and
- reducing an output current of the first H-bridge circuit and an output current of the second H-bridge circuit when the processor fixes a state of the direction signal and a state of the clock signal over a predetermined period of time.
A driving circuit for a stepping motor comprising a first coil and a second coil, the driving circuit comprising:
- a first H-bridge circuit coupled to the first coil;
- a second H-bridge circuit coupled to the second coil;
- a clock pin structured to receive a clock signal that indicates a rotational operation of the stepping motor;
- a control pin structured to receive a control signal that sets an output of the first H-bridge circuit and an output of the second H-bridge circuit to a predetermined state;
- a logic circuit structured to determine a rotational direction based on a state of the clock signal and a state of the control signal, and to generate a first internal signal and a second internal signal that respectively indicate a state of the first H-bridge circuit and a state of the second H-bridge circuit according to the clock signal;
- a first pre-driver structured to drive the first H-bridge circuit according to the first internal signal;
- and
- a second pre-driver structured to drive the second H-bridge circuit according to the second internal signal;
- wherein, when the clock signal and the control signal each remain in a predetermined state for a predetermined judgment time, the logic circuit switches a rotational direction to a direction that is the reverse of an immediately previous rotational direction.
A driving circuit for a stepping motor comprising a first coil and a second coil, the driving circuit comprising:
- a first H-bridge circuit coupled to the first coil;
- a second H-bridge circuit coupled to the second coil;
- a clock pin structured to receive a clock signal that indicates a rotational operation of the stepping motor;
- a control pin structured to receive a control signal that sets an output of the first H-bridge circuit and an output of the second H-bridge circuit to a predetermined state;
- a logic circuit structured to determine a rotational direction based on a state of the clock signal and a state of the control signal, and to generate a first internal signal and a second internal signal that respectively indicate a state of the first H-bridge circuit and a state of the second H-bridge circuit according to the clock signal;
- a first pre-driver structured to drive the first H-bridge circuit according to the first internal signal;
- and
- a second pre-driver structured to drive the second H-bridge circuit according to the second internal signal;
- wherein a control signal is a signal for switching an excitation mode between a weak excitation mode and a normal excitation mode,
- and wherein, when the control signal indicates the weak excitation mode, the logic circuit reduces an output current of the first H-bridge circuit and an output current of the second H-bridge circuit.
Dependencies are inferred from the claim text.