48
4317I–AVR–01/08
AT90PWM2/3/2B/3B
Figure 9-2.
MCU Start-up, RESET Tied to V
CC
Figure 9-3.
MCU Start-up, RESET Extended Externally
9.0.4
External Reset
An External Reset is generated by a low level on the RESET pin. Reset pulses longer than the
minimum pulse width (see
) will generate a reset, even if the clock is not running.
Shorter pulses are not guaranteed to generate a reset. When the applied signal reaches the
Reset Threshold Voltage – V
RST
– on its positive edge, the delay counter starts the MCU after
the Time-out period – t
TOUT
–
has expired.
Figure 9-4.
External Reset During Operation
V
RESET
TIME-OUT
INTERNAL
RESET
t
TOUT
V
POT
V
RST
CC
RESET
TIME-OUT
INTERNAL
RESET
t
TOUT
V
POT
V
RST
V
CC
CC