SH7108 Datasheet, PDF (409/560 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

Section 13 Motor Management Timer (MMT)
Table 13.2 Initial Values of TBRU to TBRW and Initial Output
Initial Value of TBRU to TBRW
TBR = H'0000
H'0000 < TBR ≤ Td
Td < TBR ≤ H'FFFF – 2Td
Initial Output
OLSP = 1, OLSN = 1
OLSP = 0, OLSN = 0
Positive phase: 1
Negative phase: 0
Positive phase: 0
Negative phase: 1
Positive phase: 0
Negative phase: 0
Positive phase: 1
Negative phase: 1
Positive phase: 0
Negative phase: 1
Positive phase: 1
Negative phase: 0
(9) PWM Output Generation in Operating Modes
In the operating modes, a three-phase PWM waveform is output with a non-overlap relationship
between the positive and negative phases. This non-overlap time is called the dead time.
The PWM waveform is generated from an output generation waveform generated by ANDing the
compare output waveform with the dead time generation waveform. Waveform generation for one
phase (the U-phase) is shown here. The V-phase and W-phase waveforms are generated in the
same way.
(a) Compare Output Waveform
The compare output waveform is generated by comparing the values in TCNT and TGR.
For compare output waveform U phase A (CMOUA), 0 is output if TGRUU > TCNT in the T1
interval (when TCNT is counting up), and 1 is output if TGRUU ≤ TCNT. In the T2 interval
(when TCNT is counting down), 0 is output if TGRU > TCNT, and 1 is output if TGRU ≤ TCNT.
For compare output waveform U phase B (CMOUB), 1 is output if TGRU > TCNT in the T1
interval, and 0 is output if TGRU ≤ TCNT. In the T2 interval, 1 is output if TGRUD > TCNT, and
0 is output if TGRUD ≤ TCNT.
(b) Dead Time Generation Waveform
For dead time generation waveform U phases A (DTGUA) and B (DTGUB), 1 is output as the
initial value.
TDCNT0 starts counting at the falling edge of CMOUA. DTGUA outputs 0 if TDCNT0 is
counting, and 1 otherwise.
Rev.1.00 Sep. 18, 2008 Page 375 of 522
REJ09B0069-0100