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Section 18 Multi-Function Timer Pulse Unit (MTU)
Rev. 4.00 Sep. 14, 2005 Page 599 of 982
REJ09B0023-0400
Dead Time Setting: In complementary PWM mode, PWM pulses are output with a non-
overlapping relationship between the positive and negative phases. This non-overlap time is called
the dead time.
The non-overlap time is set in the timer dead time data register (TDDR). The value set in TDDR is
used as the TCNT_3 counter start value, and creates non-overlap between TCNT_3 and TCNT_4.
Complementary PWM mode should be cleared before changing the contents of TDDR.
PWM Cycle Setting: In complementary PWM mode, the PWM pulse cycle is set in two
registersTGRA_3, in which the TCNT_3 upper limit value is set, and TCDR, in which the
TCNT_4 upper limit value is set. The settings should be made so as to achieve the following
relationship between these two registers:
TGRA_3 set value = TCDR set value + TDDR set value
The TGRA_3 and TCDR settings are made by setting the values in buffer registers TGRC_3 and
TCBR. The values set in TGRC_3 and TCBR are transferred simultaneously to TGRA_3 and
TCDR in accordance with the transfer timing selected with bits MD3 to MD0 in the timer mode
register (TMDR).
The updated PWM cycle is reflected from the next cycle when the data update is performed at the
crest, and from the current cycle when performed in the trough. Figure 18.36 illustrates the
operation when the PWM cycle is updated at the crest.
See the following part, Register Data Updating, for the method of updating the data in each buffer
register.