External Reset Pin - Fujitsu MB90460 Series Hardware Manual

4.3

External Reset Pin

The external reset pin (RSTX pin) is a dedicated pin for inputting, with an L level signal,
a reset and generating an internal reset by the L level input.
For MB90460/465 series microcontrollers, resets are generated in synchronization with
the CPU operating clock. Asynchronous resets are generated only for the external
terminals.
■ Block Diagrams of the External Reset Pin
●
Block diagram of internal reset
RSTX
Pin
HCLK: Oscillation clock
Note:
Inputs to the RSTX pin are accepted during cycles in which memory is not affected to prevent
memory from being destroyed by a reset during a write operation.
A clock is required to initialize the internal circuit. In particular, an operation with an external clock
requires clock input together with reset input.
Figure 4.3-1 Block Diagram of Internal Reset
P-ch
N-ch
CPU operating clock
(PLL multiplier circuit with a frequency of HCLK divided by 2)
Input buffer
Synchronization
circuit
CHAPTER 4 RESET
Internal reset signal
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