W77C32F-40 Nuvoton Technology Corporation of America, W77C32F-40 Datasheet - Page 45

• Manufacturer Part Number: W77C32F-40
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W77C32F-40

• Lead Free Status / Rohs Status: Supplier Unconfirmed

The W77C32 can be woken from the Power Down mode by forcing an external interrupt pin activated,
provided the corresponding interrupt is enabled, while the global enable(EA) bit is set and the external
input has been set to a level detect mode. If these conditions are met, then the low level on the
external pin re-starts the oscillator. Then device executes the interrupt service routine for the
corresponding external interrupt. After the interrupt service routine is completed, the program
execution returns to the instruction after the one which put the device into Power Down mode and
continues from there. When RGSL(EXIF.1) bit is set to 1, the CPU will use the internal RC oscillator
instead of crystal to exit Power Down mode. The microcontroller will automatically switch from RC
oscillator to crystal after clock is stable. The RC oscillator runs at approximately 2−4 MHz. Using RC
oscillator to exit from Power Down mode saves the time for waiting crystal start-up. It is useful in the
low power system which usually be awakened from a short operation then returns to Power Down
mode.
Table 5. Status of external pins during Idle and Power Down
Idle
Idle
Power Down
Power Down
MODE
PROGRAM
MEMORY
External
External
Internal
Internal
ALE
0
0
1
1
PSEN
0
0
1
1
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PORT0
Float
Publication Release Date: December 20, 2005
Float
Data
Data
W77C32/W77C032
PORT1
Data
Data
Data
Data
Address
PORT2
Data
Data
Data
Revision A5
PORT3
Data
Data
Data
Data