z8fmc16100 ZiLOG Semiconductor, z8fmc16100 Datasheet - Page 83

• Manufacturer Part Number: z8fmc16100
• Description: Z8 Encore Motor Control Flash Mcus
• Manufacturer: ZiLOG Semiconductor

PS024611-0408
Minimum PWM Pulse Width Filter
Synchronization of PWM and Analog-to-Digital Converter
width of this deadband is attributed to the number of system clock cycles specified in the
PWM Deadband register (PWMDB). The minimum deadband duration is one system
clock, and the maximum duration is 255 system clocks. During the deadband period, both
PWM outputs of a complementary pair are deasserted. The generation of deadband time
does not alter the PWM period; instead, the deadband time is subtracted from the active
time of the PWM outputs.
the PWM output.
The PWM modulator is capable of producing pulses as narrow as a single system clock
cycle in width. As the response time of external drive circuits can be slower than the
period of a system clock, a filter is implemented to enforce a minimum-width pulse on the
PWM output pins. All output pulses, whether High or Low, must be at least the minimum
number of PWM clock cycles (for more details, see
as specified in the PWM Minimum Pulse Width Filter (PWMMPF) register. If the
expected pulse width is less than the threshold, the associated PWM output does not
change state until the duty cycle value has changed sufficiently to allow pulse generation
of an acceptable width. The minimum pulse width filter also accounts for the duty cycle
variation caused by the deadband insertion. The PWM output pulse is filtered even if the
programmed duty cycle is greater than the threshold, but the pulse width decrease because
of deadband insertion causes the pulse to be too narrow. The pulse width filter value is
calculated as:
where
The PWM Minimum Pulse Width Filter register can only be written when the
cleared. Values written to this register when
The ADC on the Z8FMC16100 Series Flash MCU can be synchronized with the PWM
period. Enabling the PWM ADC trigger causes the PWM to generate an ADC conversion
signal at the end of each PWM period. Additionally, in center-aligned mode, the PWM
generates a trigger at the center of the period. Setting the ADCTRIG bit in the PWM
Control 0 register (PWMCTL0) enables ADC synchronization.
Roundup (PWMMPF)
T
MINPULSEOUT
is the shortest allowed pulse width on the PWM outputs, in seconds.
=
Figure 8
T
SYSTEMCLOCK
and
Figure 9
T
MINPULSEOUT
PWEN
x PWM
display the effect of deadband insertion on
is set will be ignored.
PWM Prescaler
PRESCALER
Minimum PWM Pulse Width Filter
Product Specification
on page 68) in width
PWEN
bit is
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