HD6433308 HITACHI [Hitachi Semiconductor], HD6433308 Datasheet - Page 189

• Manufacturer Part Number: HD6433308
• Description: Hitachi Single-Chip MicroComputer
• Manufacturer: HITACHI [Hitachi Semiconductor]

If the system clock frequency is 10MHz, then the resolution, period, and frequency of the PWM
output for each clock source are given in Table 8-3.
Table 8-3. PWM Timer Parameters for 10MHz System Clock
Internal clock frequency
Ø/2
Ø/8
Ø/32
Ø/128
Ø/256
Ø/1024
Ø/2048
Ø/4096
8.3 Operation
8.3.1 Timer Incrementation
The PWM clock source is created from the system clock (Ø) by a prescaler. The timer counter
increments on a TCNT clock pulse generated from the falling edge of the prescaler output as shown
in Figure 8-2.
Ø
Prescaler
output
TCNT clock
pulse
TCNT
Resolution =
PWM period
PWM frequency
N–1
1/clock source frequency
=
=
resolution 250
1/PWM period
Figure 8-2. TCNT Increment Timing
Resolution
200ns
800ns
3.2µs
12.8µs
25.6µs
102.4µs
204.8µs
409.6µs
175
N
PWM period
50µs
200µs
800µs
3.2ms
6.4ms
25.6ms
51.2ms
102.4ms
PWM frequency
20kHz
5kHz
1.25kHz
312.5Hz
156.3Hz
39.1Hz
19.5Hz
9.8Hz
N+1