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Motor Output
60
Juno Step Motor Control IC User Guide
10
Figure 10-1:
PWM High/Low
Encoding
In PWM High/Low mode two output pins are used per motor or per motor phase, allowing separate high-side/low-
side control of each bridge switch. In this scheme, as
shows, the high side output and the low side output
are never active at the same time, and there is generally a period of time when neither output is active. This period of
time is called the dead time, and provides a shoot through protection function for MOSFET or IGBT switches.
Figure 10-2:
PWM High/Low
Signal
Generation
The dead time is specified in
nSecs. The correct value can generally be determined from the MOSFET or IGBT IC
manufacturer’s data sheet, or you can call PMD Corp. technical support if you have questions.
In addition to dead time, some high side switch drive circuitry requires a minimum amount of off time to allow the
charge pump circuitry to refresh. This parameter specifies this refresh time and has units of nSecs. The related
parameter of refresh time period, which is the time interval between these off time refreshes has units of current loop
cycles.
It is also possible to control the maximum allowed PWM duty cycle. This may be useful to limit the effective voltage
presented to the motor windings, or to provide some other needed off-time for the switching amplifier circuitry.
0 / 1024
(100% negative
command)
1
0
1
0
1
0
1
0
1
0
1024 / 1024
(100% positive
command)
1023 / 1024
(large positive
command)
512 / 1024
(zero command)
1 / 1024
(large negative
command)
The Juno step motor control IC default values for dead time, refresh time, and refresh period are set to be max-
imally safe but are not appropriate to drive typical switching hardware. For proper amplifier function these values
must be set with values appropriate for the connected switching circuitry.
PWM High-Side
Drive
1
0
PWM Low-Side
Drive
1
0
Dead Time
Dead Time
Содержание Juno MC71112
Страница 12: ...The Juno IC Family 12 Juno Step Motor Control IC User Guide 1 This page intentionally left blank ...
Страница 18: ...Functional Characteristics 18 Juno Step Motor Control IC User Guide 2 This page intentionally left blank ...
Страница 22: ...Electrical Characteristics 22 Juno Step Motor Control IC User Guide 3 This page intentionally left blank ...
Страница 26: ...Timing Diagrams 26 Juno Step Motor Control IC User Guide 4 This page intentionally left blank ...
Страница 46: ...Operational Overview 46 Juno Step Motor Control IC User Guide 7 This page intentionally left blank ...
Страница 54: ...Microstep Waveform Generation 54 Juno Step Motor Control IC User Guide 8 This page intentionally left blank ...
Страница 70: ...Internal Profile Generation 70 Juno Step Motor Control IC User Guide 11 This page intentionally left blank ...
Страница 78: ...Motion Monitoring Control 78 Juno Step Motor Control IC User Guide 12 This page intentionally left blank ...
Страница 86: ...Drive DC Bus Safety 86 Juno Step Motor Control IC User Guide 13 This page intentionally left blank ...
Страница 100: ...Application Notes MC74113 MC75113 100 Juno Step Motor Control IC User Guide 15 Figure 15 3 Drive Safety and Monitoring ...
Страница 103: ...Application Notes MC74113 MC75113 Juno Step Motor Control IC User Guide 103 15 Figure 15 4 Leg Current Sensing ...
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