mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 261

• Manufacturer Part Number: mcf51ac256a
• Description: Mcf51ac Flexis
• Manufacturer: Freescale Semiconductor, Inc

FTMxDEADTIME register defines the deadtime delay which can be used for all FTM channels. The
DTPS[1:0] bits define the prescaler for the system clock and the DTVAL[5:0] bits define the deadtime
modulo (number of the deadtime prescaler clocks).
The deadtime delay insertion ensures that no two complementary signals (channel (n) and (n+1)) drive the
active state at the same time.
For POL(n) = 0, POL(n+1) = 0 and deadtime enabled, a rising edge on the output of channel (n) remains
low for the duration of the deadtime delay, after which the rising edge appears on the output. Similarly,
when a falling edge is due on the output of channel (n), the channel (n+1) output remains low for the
duration of the deadtime delay, after which the channel (n+1) output will have a rising edge.
For POL(n) = 1, POL(n+1) = 1 and deadtime enabled, a falling edge on the output of channel (n) remains
high for the duration of the deadtime delay, after which the falling edge appears on the output. Similarly,
when a rising edge is due on the output of channel (n), the channel (n+1) output remains high for the
duration of the deadtime delay, after which the channel (n+1) output will have a falling edge.
If the deadtime delay is greater than or equal to the channel (n) duty cycle (FTMxC(n+1)VH:L -
FTMxC(n)VH:L), then the channel (n) output is always 0. Equally, if the deadtime delay is greater than or
equal to the channel (n+1) duty cycle (FTMxMODH:L - FTMxCNTINH:L - (FTMxC(n+1)VH:L -
FTMxC(n)VH:L)), then the channel (n+1) output is always 0.
Freescale Semiconductor
channel (n+1) output
channel (n+1) output
channel (n) output
channel (n+1) match
channel (n) output
(before deadtime
(before deadtime
(after deadtime
(after deadtime
channel (n) match
FTM counter
insertion)
insertion)
insertion)
insertion)
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
Figure 11-73. Deadtime insertion with ELSnB:ELSnA = 1:0
FlexTimer Module (FTMV1)
11-61