SH7101 Datasheet, PDF (216/486 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

8. Multi-Function Timer Pulse Unit (MTU)
The positive phase/negative phase off timing is generated by a compare-match with the solid-line
counter, and the on timing by a compare-match with the dotted-line counter operating with a delay
of the dead time behind the solid-line counter. In the T1 period, compare-match a that turns off the
negative phase has the highest priority, and compare-matches occurring prior to a are ignored. In
the T2 period, compare-match c that turns off the positive phase has the highest priority, and
compare-matches occurring prior to c are ignored.
In normal cases, compare-matches occur in the order a → b → c → d (or c → d → a' → b'), as
shown in figure 8.40.
If compare-matches deviate from the a → b → c → d order, since the time for which the negative
phase is off is less than twice the dead time, the figure shows the positive phase is not being turned
on. If compare-matches deviate from the c → d → a' → b' order, since the time for which the
positive phase is off is less than twice the dead time, the figure shows the negative phase is not
being turned on.
If compare-match c occurs first following compare-match a, as shown in figure 8.41, compare-
match b is ignored, and the negative phase is turned off by compare-match d. This is because
turning off of the positive phase has priority due to the occurrence of compare-match c (positive
phase off timing) before compare-match b (positive phase on timing) (consequently, the waveform
does not change since the positive phase goes from off to off).
Similarly, in the example in figure 8.42, compare-match a' with the new data in the temporary
register occurs before compare-match c, but other compare-matches occurring up to c, which turns
off the positive phase, are ignored. As a result, the positive phase is not turned on.
Thus, in complementary PWM mode, compare-matches at turn-off timings take precedence, and
turn-on timing compare-matches that occur before a turn-off timing compare-match are ignored.
Rev.2.00 Sep. 27, 2007 Page 182 of 448
REJ09B0394-0200