TMP88FW45FG Datasheet, PDF (220/276 Pages) Toshiba Semiconductor – 8 Bit Microcontroller

18. 8-Bit High-speed PWM (HPWM0 and HPWM1)
18.3 Functional Description
TMP88FW45FG
Data
"10h"
"11h"
"F0h"
6.4 µs
400 ns
425 ns
6.000 µs
6.4 µs
400 ns
425 ns
6.000 µs
Figure 18-3 7-Bit Mode
Note: The resolution of the LSB 1 bit (25 nsec) is a typical value and its precision is not guaranteed.
18.3.1.3 6-bit mode
In 6-bit mode, it is possible to generate a pulse with 3.2 µs period and approximately 313 kHz frequency
(when X1 = 20 MHz).
6 high-order bits
× 50 ns
3.2 µs
Varies with value of 2
low-order bits
6 high-order bits
× 50 ns
3.2 µs
In 6-bit mode, the period is comprised of 6 bits (period = 2⁶ × 50 ns) and two other bits provide a 12.5
ns resolution. However, because the actually obtained resolution is 25 ns, said resolution is accomplished
artificially. To obtain a 12.5 ns resolution, the first, second, and third pulses are output by adding 25 ns, 0
ns, and 25 ns, respectively. In this way, a 12.5 ns resolution is realized as being “equivalent to.”
The minimum equivalent width of the pulse is 0.2 µs (data “10”), and the maximum equivalent width of
the pulse is 3.0 µs (data “F0”: “3B” + “0”).
7
0
Data register
6 high-order bits 2 low-order bits
Pulse width = (6 high-order bits of data × 50 ns) + (2 low-order bits of data *)
* The equivalent plus times in 2 low-order bits of data are shown below.
2-bit data
00
01
10
11
Equivalent plus time
0 ns
12.5 ns
25 ns
37.5 ns
Figure 18-4 Shows a typical waveform in 6-bit mode. (The values are for X1 = 20 MHz.)
Page 208