Datasheet

© 2010 Microchip Technology Inc. DS70141F-page 103
dsPIC30F3010/3011
FIGURE 15-4: DEAD-TIME TIMING DIAGRAM
15.8 Independent PWM Output
An Independent PWM Output mode is required for
driving certain types of loads. A particular PWM output
pair is in the Independent Output mode when the
corresponding PMOD bit in the PWMCON1 register is
set. No dead-time control is implemented between
adjacent PWM I/O pins when the module is operating
in the Independent mode and both I/O pins are allowed
to be active simultaneously.
In the Independent mode, each duty cycle generator is
connected to both of the PWM I/O pins in an output
pair. By using the associated Duty Cycle register and
the appropriate bits in the OVDCON register, the user
may select the following signal output options for each
PWM I/O pin operating in the Independent mode:
• I/O pin outputs PWM signal
• I/O pin inactive
• I/O pin active
15.9 Single Pulse PWM Operation
The PWM module produces single pulse outputs when
the PTCON control bits, PTMOD<1:0> = 10. Only
edge-aligned outputs may be produced in the Single
Pulse mode. In Single Pulse mode, the PWM I/O pin(s)
are driven to the active state when the PTEN bit is set.
When a match with a Duty Cycle register occurs, the
PWM I/O pin is driven to the inactive state. When a
match with the PTPER register occurs, the PTMR
register is cleared, all active PWM I/O pins are driven
to the inactive state, the PTEN bit is cleared and an
interrupt is generated.
15.10 PWM Output Override
The PWM output override bits allow the user to
manually drive the PWM I/O pins to specified logic
states, independent of the duty cycle comparison units.
All control bits associated with the PWM output over-
ride function are contained in the OVDCON register.
The upper half of the OVDCON register contains six
bits, POVDxH<3:1> and POVDxL<3:1>, that determine
which PWM I/O pins will be overridden. The lower half
of the OVDCON register contains six bits,
POUTxH<3:1> and POUTxL<3:1>, that determine the
state of the PWM I/O pins when a particular output is
overridden via the POVD bits.
15.10.1 COMPLEMENTARY OUTPUT MODE
When a PWMxL pin is driven active via the OVDCON
register, the output signal is forced to be the comple-
ment of the corresponding PWMxH pin in the pair.
Dead-time insertion is still performed when PWM
channels are overridden manually.
15.10.2 OVERRIDE SYNCHRONIZATION
If the OSYNC bit in the PWMCON2 register is set, all
output overrides performed via the OVDCON register
are synchronized to the PWM time base. Synchronous
output overrides occur at the following times:
• Edge-Aligned mode, when PTMR is zero.
• Center-Aligned modes, when PTMR is zero and
when the value of PTMR matches PTPER.
Duty Cycle Generator
PWMxH
PWMxL
Dead Time Dead Time