AN2517 Freescale Semiconductor / Motorola, AN2517 Datasheet - Page 20

• Manufacturer Part Number: AN2517
• Description: 3-Phase Sine Wave Generator with Dead-Time Correction TPU Function Set
• Manufacturer: Freescale Semiconductor / Motorola

AN2517/D
Synchronization
signal for 3-Phase
Sine Wave
Generator with
Dead-Time
Correction
(3SinDt_sync)
Synchronized Change
of PWM Prescaler
And Synchronization
Signal Prescaler
20
3-Phase Sine Wave Generator with Dead-Time Correction TPU Function Set (3SinDt) MOTOROLA
The 3SinDt_sync TPU function uses information obtained from 3SinDt PWM
functions, the actual PWM center times and the PWM periods. This allows a
signal to be generated, which tracks the changes in the PWM period and is
always synchronized with the PWM. The synchronization signal is a positive
pulse generated repeatedly after the prescaler or presc_copy PWM periods
(see next paragraph). The low to high transition of the pulse can be adjusted
by a parameter, either negative or positive, to go a number of TCR1 TPU cycles
before or after the PWM period center time. The pulse width pw is another
synchronization signal parameter.
The 3SinDt_sync TPU function actually uses the presc_copy parameter
instead of the prescaler parameter. The prescaler parameter holds the
prescaler value that is copied to the presc_copy by the 3SinDt_bottom function
at the time the PWM parameters are reloaded. This ensures that new prescaler
values for the PWM signals, as well as the synchronization signal, are applied
at the same time. Write the synchronization signal prescaler parameter
address to the sync_presc_addr parameter to enable this mechanism. Write 0
to disable it, and remember to set the synchronization signal presc_copy
parameter instead of the prescaler parameter in this case.
move > 0
move > 0
prescaler = 1
prescaler = 1
move < 0
move < 0
prescaler = 2
prescaler = 2
Freescale Semiconductor, Inc.
For More Information On This Product,
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Figure 8. Synchronization signal adjustment examples
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pw
pw
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pw
pw
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