Fujitsu F2MC-8FX Hardware Manual page 99

Power-on reset/low-voltage detection reset
A power-on reset is generated when the power is turned on.
Some 5-V products have a low-voltage detection reset circuit integrated.
The low-voltage detection reset circuit generates a reset if the power supply voltage falls below a
predetermined level.
The logical function of the low-voltage detection reset is completely equivalent to the power-on reset. All
the text in this manual concerning power-on resets applies to low-voltage detection resets as well.
For details about low-voltage detection resets, see "CHAPTER 25
RESET CIRCUIT".
Clock supervisory reset
Some 5 V products have an on-board clock supervisor.
The clock supervisor monitors the main oscillation clock and sub oscillation clock, and generates a reset if
oscillation stops abnormally, not caused by a predefined state transition. After reset, a clock generated by
the on-board RC oscillation circuit is supplied internally.
See CHAPTER 26 CLOCK SUPERVISOR for details about the clock supervisor.
Reset Time
In the case of a software reset or watchdog reset, the reset time consists of a total of three machine clock
cycles: one machine clock cycle at the machine clock frequency selected before the reset, and two machine
clock cycles at the machine clock frequency initially set after the reset (1/32 of the main clock frequency).
However, the reset time may be extended in machine clock cycles of the frequency selected before the
reset, via the RAM access protection function which suppresses resets during RAM access. In addition,
when in main clock oscillation stabilization standby mode, the reset time is further extended for the
oscillation stabilization wait time.
External resets and resets are also affected by the RAM access protection function and main clock
oscillation stabilization wait time.
In the case of a power-on reset or low-voltage detection reset, the reset continues during the oscillation
stabilization wait time.
Reset Output
The reset pin does not have an output function.
CHAPTER 7 RESET
LOW-VOLTAGE DETECTION
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