MOTOR DRIVE CIRCUIT

• US 20130141025A1
• Filed: 10/16/2012
• Published: 06/06/2013
• Est. Priority Date: 10/17/2011
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Inventors: Takamori, Yasuyuki, Muragi, Masashi
• Granted Patent: US 9,035,585 B2
• Time in Patent Office: Days
• US Class Current: 318/400.21
• CPC Class Codes: H02H 3/003 responsive to reversal of power transmission direction reversal of direct current H02H3/18
• CPC Class Codes: H02P 6/24 Arrangements for stopping
• CPC Class Codes: H02P 6/26 Arrangements for controlling single phase motors

Abstract

A motor-drive circuit includes a detection circuit to detect a reverse current to flow in a direction from a first sink-side transistor to a second source-side transistor or in a direction from a second sink-side transistor to a first source-side transistor, a disable circuit to disable a detection output of the detection circuit during a predetermined time period from a start of detection of the reverse current performed by the detection circuit, a first inhibit circuit to inhibit synchronous rectification according to a detection output of the detection circuit when the predetermined time period has elapsed from a start of detection of the reverse current performed by the detection circuit, and a second inhibit circuit.

Claims

1. A motor drive circuit characterized in that

when first source-side and second sink-side transistors and second source-side and first sink-side transistors are turned on/off in a complementary manner so as to supply a drive current to a drive coil connected between a first connection point of the first source-side transistor and the first sink-side transistor connected in series and a second connection point of the second source-side transistor and the second sink-side transistor connected in series, the first or the second sink-side transistor is turned on/off according to a PWM signal and synchronous rectification is performed for the motor drive circuit such that the first or the second source-side transistor in an off state is turned on and kept on during a time period during which the first or the second sink-side transistor is off according to the PWM signal, and that

the motor drive circuit includes:

a detection circuit configured to detect a reverse current to flow in a direction from the first sink-side transistor to the second source-side transistor or in a direction from the second sink-side transistor to the first source-side transistor;

a disable circuit configured to disable a detection output of the detection circuit during a predetermined time period from a start of detection of the reverse current performed by the detection circuit;

a first inhibit circuit configured to inhibit the synchronous rectification according to a detection output of the detection circuit when the predetermined time period has elapsed from a start of detection of the reverse current performed by the detection circuit; and

a second inhibit circuit configured to inhibit the synchronous rectification irrespective of an operation of the first inhibit circuit, when each on-duty period of the PWM signal to turn on the first or the second sink-side transistor is shorter than the predetermined time period.

2. The motor drive circuit according to claim 1, further comprising

a third inhibit circuit configured to inhibit the synchronous rectification irrespective of an operation of the first or the second inhibit circuit, when the PWM signal has a period in which a direction of a current supplied to the drive coil is changed to a direction opposite to a direction thereof at a time of a start of the synchronous rectification.

3. The motor drive circuit according to claim 1, wherein

the second inhibit circuit is configured to permit the synchronous rectification, when the synchronous rectification is inhibited by the second inhibit circuit and each on-duty period of the PWM signal is longer than the predetermined time period.

4. The motor drive circuit according to claim 2, wherein

the third inhibit circuit is configured to permit the synchronous rectification, when the synchronous rectification is inhibited by the third inhibit circuit and the PWM signal has a period in which a direction of a current supplied to the drive coil is not changed from a direction thereof at a time of a start of the synchronous rectification.