HD6413308 Hitachi Semiconductor, HD6413308 Datasheet - Page 155

• Manufacturer Part Number: HD6413308
• Description: Hitachi Single-Chip MicroComputer
• Manufacturer: Hitachi Semiconductor

If external clock input is selected, the FRC increments on the rising edge of the FTCI clock signal.
Figure 6-6 shows the increment timing.
The pulse width of the external clock signal must be at least 1.5 system clock (Ø) periods. The
counter will not increment correctly if the pulse width is shorter than one Ø period.
Ø
Prescaler
output
FRC clock
pulse
FRC
FTCI
FRC clock pulse
FRC
Ø
N – 1
Ø
FTCI
Figure 6-6. Increment Timing for External Clock Source
Figure 6-5. Increment Timing for Internal Clock Source
Figure 6-7. Minimum External Clock Pulse Width
N
N
140
N + 1
N + 1