STK6877 查看數據表（PDF） - SANYO -> Panasonic
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STK6877 Datasheet PDF : 8 Pages
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STK6877
4. Braking Operation Procedures
There are three methods for applying braking to the motor.
(a) Setting both the A and B phase inputs to low. (This shorts the
motor pins.)
(b) Setting the PWM input low. (This effects motor flywheel
current regenerative braking.)
(c) After setting the PWM input low, setting both the A and B
phase inputs to low. (This is the combination of methods (a)
and (b).)
(a) When braking method (a) is used, damping is applied through
the lower MOSFETs. (This stops the motor quickly.) Since this
method is equivalent to shorting the motor, the braking flywheel
current rises radically, and the lower MOSFETs go to the
overload state. As shown in Figure 9, F3 and F4 go to the
overload state, and Figure 10 shows the flywheel current that
flows in this braking method. Thus if this method is to be used,
the user must confirm that, under the conditions of the actual
application circuit, the flywheel current that flows in the lower
FETs does not exceed the maximum rated current range for the
hybrid IC.
Note: (*) Braking applied during reverse motor rotation
Figure 9 Brake Method (a) Current Flow
When brake method (b) is used, the motor drive current from
before braking is applied is released in the lower MOSFETS thus
resulting in a motor stopping operation. (This is a free running
motor stop method.) Although the MOSFETs will not be
overloaded, the braking is not as fast.
Figure 10 Flywheel Current Flowing in the
Lower FET (F4)
When brake method (c) is used, first the PWM input is set to
low, and the motor’s rotational energy is released to a certain
degree. Then full braking is applied by setting both the A and B
phase inputs to low. This method allows the flywheel current that
flows in the lower MOSFETs to be held to within the maximum
rated range by first applying method (b) braking, and then when
the motor’s rotational energy has been reduced, applying method
(a) braking to stop the motor.
Note: (*) Braking applied during reverse motor rotation
Figure 11 Current Path in Brake Method (a)
No. 4874-6/8
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