AN2517 Freescale Semiconductor / Motorola, AN2517 Datasheet - Page 17

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

Minimum Pulse Width
MOTOROLA 3-Phase Sine Wave Generator with Dead-Time Correction TPU Function Set (3SinDt)
The TPU cannot generate PWM signals with duty cycle ratios very close to 0%
or 100%. The minimum pulse width that the TPU can be guaranteed to correctly
generate is determined by the TPU function itself and by the activity on the
other channels. When the TPU function is requested to generate a narrower
pulse a collision can occur. To prevent this, the parameter MPW (minimum
pulse width) is introduced. The TPU functions 3SinDt_top and 3SinDt_bottom
limit the narrowest generated pulse widths to MPW. The CPU program should
check, and limit, the maximum amplitude of the Stator Reference Voltage
Vector. The maximum amplitude of the Stator Reference Voltage Vector should
be less than
If this is not the case, the TPU function will start to limit the minimum pulse
widths to MPW to prevent a collision, and the duty cycle ratio traces will be
deformed as shown on
The MPW is written by the CPU. The MPW depends on the whole TPU unit
configuration, especially the lengths of the longest states of other functions,
and their priorities, running on the same TPU. The MPW has to be correctly
calculated at the time the whole TPU unit is configured.
Freescale Semiconductor, Inc.
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Detailed Function Description
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AN2517/D
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