TB6560AFG Datasheet, PDF (17/34 Pages) Toshiba Semiconductor – PWM Chopper-Type Bipolar Driver IC for Stepping Motor Control

10. Current Control Modes (Effects of Decay Modes)
• Increasing the current (sine wave)
TB6560AHQ/AFG
Predefined
Current Level
Charge
Slow
Predefined
Current Level
Slow
Charge
Slow
Fast
Charge
Fast _Charge
Fast
Slow
Fast
• Decreasing the current with a high decay rate (The current decay rate in Mixed Decay mode is the ratio
between the time in Fast-Decay mode (discharge time after MDT) and the remainder of the period.)
Predefined
Current Level
Slow
Charge
Fast
Slow
Charge
Since the current decays quickly, it can be
decreased to the predefined value in a short time.
Fast
Predefined
Current Level
Slow
Slow
Fast
Fast
Charge
• Decreasing the current with a low decay rate (The current decay rate in Mixed Decay mode is the ratio
between the time in Fast-Decay mode (discharge time after MDT) and the remainder of the period.)
Predefined
Current Level
Slow
Charge
Fast _Charge
Slow
Since the current decays slowly, decreasing the current
to the predefined value takes a long time (or the current
cannot be properly decreased to the predefined value).
Fast
Slow
Fast
Predefined
Current Level
Slow
Fast
During Mixed Decay and Fast Decay modes, if the predefined current level is less than the output
current at the RNF (current monitoring point), the Charge mode in the next chopping cycle will
disappear (though the current control mode is briefly switched to Charge mode in actual operations for
current sensing) and the current is controlled in Slow and Fast Decay modes (mode switching from Slow
Decay mode to Fast Decay mode at the MDT point).
Note: The above figures are rough illustration of the output current. In actual current waveforms, transient response
curves can be observed.
17
2011-01-18