mc9s12e256 Freescale Semiconductor, Inc, mc9s12e256 Datasheet - Page 361

• Manufacturer Part Number: mc9s12e256
• Description: Hcs12 Microcontrollers 16-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

For a given PWM pair, whether the odd or even PMFVAL register is active depends on either:
To correct deadtime distortion, software can decrease or increase the value in the appropriate PMFVAL
register.
In the complementary channel operation, ISENS selects one of three correction methods:
Freescale Semiconductor
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The state of the current status pin, ISx, for that driver
The state of the odd/even correction bit, IPOLx, for that driver
In edge-aligned operation, decreasing or increasing the PWM value by a correction value equal to
the deadtime typically compensates for deadtime distortion.
In center-aligned operation, decreasing or increasing the PWM value by a correction value equal
to one-half the deadtime typically compensates for deadtime distortion.
Manual correction
Automatic current status correction during deadtime
Automatic current status correction when the PWM counter value equals the value in the PWM
counter modulus registers
1
2
3
Assume the user will provide current status sensing circuitry causing the
voltage at the corresponding input pin to be low for positive current and high
for negative current. In addition, it assumes the top PWMs are PWM 0, 2,
and 4 while the bottom PWMS are PWM 1, 3, and 5.
The current status pins can be used as general purpose input/output ports.
The polarity of the ISx pin is latched when both the top and bottom PWMs are off. At the 0%
and 100% duty cycle boundaries, there is no deadtime, so no new current value is sensed.
Current is sensed even with 0% or 100% duty cycle.
ISENS
00
01
10
11
No correction
Manual correction
Current status sample correction on pins IS0, IS1, and IS2 during deadtime
Current status sample on pins IS0, IS1, and IS2
At the half cycle in center-aligned operation
At the end of the cycle in edge-aligned operation
Table 11-47. Correction Method Selection
MC9S12E256 Data Sheet, Rev. 1.08
1
Chapter 11 Pulse Width Modulator with Fault Protection (PMF15B6CV2)
NOTE
Correction Method
3
2
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