AN2515 Freescale Semiconductor / Motorola, AN2515 Datasheet - Page 12

• Manufacturer Part Number: AN2515
• Description: 3-Phase Sine Wave Generator - 3 outputs version TPU Function Set
• Manufacturer: Freescale Semiconductor / Motorola

AN2515/D
12
3-Phase Sine Wave Generator – 3 outputs version TPU Function Set (3Sin3)
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.
When 3Sin3 is running alone on one TPU, the minimum pulse width can be
calculated according to
high to low transition runs the LH_C7 state that sets the following low to high
transition. The LH_C7 state lasts 26 IMB clock cycles (see
is preceded by the Time Slot Transition (TST), which takes 10 or 14 IMB clock
cycles. So the time necessary to set the next transition, that corresponds to
MPW, is 40 IMB clock cycles.
Note that the MPW is not entered into the parameter RAM in IMB clock
cycles, but in TCR1 clock cycles. It is recommended for the 3Sin3 function
that the TCR1 clock is configured for its maximum speed, which is the IMB
clock divided by 2. In this case the MPW = 20.
Freescale Semiconductor, Inc.
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Figure 6. Timing of the worst case


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Figure 5. Effect of limitation


6. This illustrates the worst case timing. The
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