Functional Description
14-20
ADSP-BF50x Blackfin Processor Hardware Reference
Special Consideration for PWM Operation in
Over-Modulation
The Three-Phase PWM Timing Unit can produce PWM signals with
variable duty-cycle values at the PWM output pins. At the extremities of
the modulation process, both 0% and 100% modulation (termed
full off mode
and
full on mode
, respectively) are possible. In between, for
other duty cycle values, the operation is termed
normal modulation
.
•
Full On Mode
. The PWM for any pair of PWM signals is said to
operate in full on mode when the desired high side output of the
Three-Phase PWM Timing Unit is in the “on” state (low or high as
specified by
PWM_POLARITY
bit of the
PWM_CTRL
register) between
successive
PWM_SYNC
rising edges. This state may be entered by vir-
tue of the commanded duty cycle values (in conjunction with the
PWM_DT
register).
•
Full Off Mode
. The PWM for any pair of PWM signals is said to
operate in full off mode when the desired high side output of the
Three-Phase PWM Timing Unit is in the “off” state (high or low as
specified by the
PWM_POLARITY
bit of the
PWM_CTRL
register) between
successive
PWM_SYNC
pulses. This state may be entered by virtue of
the commanded duty cycle values (in conjunction with the
PWM_DT
register).
•
Normal Modulation
. The PWM for any pair of PWM signals is
said to operate in normal modulation when the desired output duty
cycle is other than 0% or 100% between successive
PWM_SYNC
pulses.
Certain situations exist whereby it is necessary to transition into or out of
full on mode or full off mode in order to insert additional “emergency
dead time” delays to prevent potential shoot-through conditions in the
inverter. Crossover usage also can potentially cause outputs to violate
shoot-through condition criteria, as described in
“Crossover Feature” on
page 14-25
. These transitions are detected automatically and, if
Summary of Contents for EZ-KIT Lite ADSP-BF506F
Page 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Page 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...