TMP91C824
91C824-109
2008-02-20
(4)
8-bit PWM (Pulse width modulation) output mode
This mode is only valid for TMRA0. In this mode, a PWM pulse with the maximum
resolution of 8 bits can be output.
When TMRA0 is used the PWM pulse is output on the TA1OUT pin. TMRA1 can
also be used as an 8-bit timer.
The timer output is inverted when the up counter (UC0) matches the value set in
the timer register TA0REG or when 2
n
counter overflow occurs (n
=
6, 7 or 8 as
specified by TA01MOD<PWM01:00>). The up counter UC0 is cleared when 2
n
counter
overflow occurs.
The following conditions must be satisfied before this PWM mode can be used.
Value set in TA0REG < Value set for 2
n
counter overflow
Value set in TA0REG
≠
0
Figure 3.7.16 8-Bit PWM Waveforms
Figure 3.7.17 shows a block diagram representing this mode.
Figure 3.7.17 Block Diagram of 8-Bit PWM Mode
TA1OUT
2
n
overflow
(INTTA0 interrupt)
t
PWM
(PWM cycle)
TA0REG and
UC0 match
TA01MOD
<PWM01:00>
TA1FFCR
<TA1FFIE>
Internal data bus
Shift trigger
Clear
8-bit up counter
(UC0)
TA01RUN<TA0RUN>
Selector
TA0IN
φ
T1
φ
T4
φ
T16
TAFF1
TA1OUT
TA0REG
Register buffer
Selector
TA01RUN<TA0RDE>
Invert
TA0REG-WR
INTTA0
TA01MOD<TA0CLK1:0>
Overflow
2
n
overflow
control
Comparator