Vault 7: Projects
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© 2010 Microchip Technology Inc. Preliminary DS39735A-page 47-33
Section 47. Motor Control PWM
Motor Control
PWM
47
47.12 PWM DEAD-TIME CONTROL
Each complementary output pair for the PWM module has a 6-bit down counter that is used to
produce the dead-time insertion. As shown in Figure 47-17, each dead-time unit has a rising
and falling edge detector connected to the duty cycle comparison output.
One of the two possible dead times is loaded into the timer on the detected PWM edge event.
Depending on whether the edge is rising or falling, one of the transitions on the complementary
outputs is delayed until the timer counts down to zero. Figure 47-18 shows a timing diagram
indicating the dead-time insertion for one pair of PWM outputs. The use of two different dead
times for the rising and falling edge events has been exaggerated in the figure for clarity.
Figure 47-17: Dead-Time Unit Block Diagram for One Output Pin Pair
Figure 47-18: Dead-Time Insertion Diagram
Low-Side PWM Signal
to Output Pin
High-Side PWM Signal
to Output Pin
Zero Compare
Clock Control
6-Bit Down Counter
PWM
T
CY
Dead Time A Dead Time B
Dead-Time
Select Logic
Prescaler
Generator
Input
PWM Generator
PWMxH3:PWMxH1
PWMxL3:PWMxL1
Time Selected by DTS3A:DTS1A Bits (A or B) Time Selected by DTS3I:DTS1I Bits (A or B)
PWMxH3:PWMxH1
PWMxL3:PWMxL1
Dead Time = 0
Non-Zero
Dead Time
Protego_Release_01_05-Related-OEM-Documentation-PIC24FJ32MC10X-Reference_Manual-Section47-Motor_Control_PWM.pdf