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SLA7080MPR 数据表(PDF) 8 Page - Sanken electric |
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SLA7080MPR 数据表(HTML) 8 Page - Sanken electric |
8 / 18 page 8 SANKEN ELECTRIC CO., LTD. 28610.23, Rev. 1 Unipolar 2-Phase Stepping Motor Driver ICs SLA7080M Series > VOCP the motor coil short-circuit protection starts its operation. Coil short circuit and the protection circuit behavior are illus- trated in figure 4. Motor Coil Open Protection (Load Open Circuit) (Patent pending.) This function operates by detecting polarity reversal of voltage VRS on the internal sense resistors. After the state is confirmed, the device shuts down the outputs. This allows detection of a wire of the motor coil breaking. Coil open circuit and the protection circuit behavior are illustrated in figure 5. In a unipolar topology, an undetected broken wire on an out- put pin (motor coil), can cause destruction of the driver due to overheating. This is because after the wire breaks, the connected driver MOSFET repeatedly undergoes avalanche breakdown at PWM turn-off, due to the higher energy applied from back electromagnetic force, as the energy stored in the motor coil is dissipated. Avalanche breakdown occurs when the output voltage surpasses the breakdown voltage between the drain and source of the MOSFET. Although the MOSFETs in the SLA7080M series have an ample avalanche breakdown rating for rated operating temperatures, the avalanche breakdown rating decreases as the operating temperature rises (as avalanche breakdown is repeated). When the SLA7080M series protection circuit detects avalanche breakdown, it allows the breakdown to repeat 3 times to prevent false detections and then turns off the MOSFET outputs before overheating can occur. The detection function operates as follows. When the wire of the motor coil is broken, the regenerating current that can reach the MOSFET breakdown level flows during the PWM off-time. Although the detection voltage, VRS, has negative potential in normal operation, when a wire breaks in the motor coil, positive potential appears during a PWM off-time. That is to say, wire breakage in the motor coil can be detected, when VRS is detected with positive potential during PWM off-time. In addition to requiring three breakdown cycles to confirm the Figure 4. Motor coil short circuit protection operation Figure 5. Motor coil open circuit protection in unipolar configuration, (A) PWM normal operation, (B) PWM operation with motor partially disconnected or broken wire in coil; VM is the motor control voltage SLA7080M 0 VREF VOCP Coil short circuit VG VG Stepper Motor Normal current VRS RS VRS Output disable Coil short circuit SLA7080M 0 VREF 0 0 VG VOUT VOUT VM 2 × VM VDSS VG Stepper Motor IOFF ION VOUT VRS RS VRS IOFF ION SLA7080M 0 VREF Avalanche breakdown 0 0 VG VG Stepper Motor Disconnection RS VRS Open detection (A) (B) |
类似零件编号 - SLA7080MPR |
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类似说明 - SLA7080MPR |
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