EZ80F91MCU ZILOG [Zilog, Inc.], EZ80F91MCU Datasheet - Page 141

• Manufacturer Part Number: EZ80F91MCU
• Description: eZ80Acclaim-TM Flash Microcontrollers
• Manufacturer: ZILOG [Zilog, Inc.]

Watch-Dog Timer
Figure 24. Watch-Dog Timer Block Diagram
PS019209-0504
Watch-Dog Timer Overview
System Clock
RTC Clock
The Watch-Dog Timer (WDT) helps protect against corrupt or unreliable software,
power faults, and other system-level problems which can place the CPU into
unsuitable operating states. The eZ80F91 WDT features:
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•
•
•
Figure 24 illustrates a block diagram of the Watch-Dog Timer.
Oscillator
WDT
Four programmable time-out periods: 2
Three selectable WDT clock sources:
–
–
–
A selectable time-out response: a time-out can be configured to generate
either a RESET or a nonmaskable interrupt (NMI)
A WDT time-out RESET indicator flag
Internal RC oscillator
System clock
Real-Time Clock source (on-chip 32 Khz crystal oscillator or 50/60 Hz
signal)
WDT_CLK
Time-out Compare Logic
(WDT_PERIOD)
P R E L I M I N A R Y
Upcounter
28-Bit
18
, 2
22
, 2
25
RESET
NMI to eZ80 CPU
WDT Control Logic
, and 2
Control Register/
Reset Register
Data[7:0]
Product Specification
27
®
clock cycles
eZ80F91 MCU
Watch-Dog Timer
122