W83627UHG Nuvoton Technology Corporation of America, W83627UHG Datasheet - Page 159

• Manufacturer Part Number: W83627UHG
• Description: IC I/O CONTROLLER 128-QFP
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W83627UHG

• Applications: PC's, PDA's
• Interface: LPC
• Voltage - Supply: 3.3V, 5V
• Package / Case: 128-XFQFN
• Mounting Type: Surface Mount
• Pin Count: 128
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

W83627UHG
15. WATCHDOG TIMER
Pin 77 is the WDTO# pin in the W83627UHG.
The Watchdog Timer of the W83627UHG consists of an 8-bit programmable time-out counter and a
control and status register. The time-out counter ranges from 1 to 255 minutes in the minute mode, or
1 to 255 seconds in the second mode. The units of Watchdog Timer counter are selected at Logical
Device 8, CR[F5h], bit[3]. The time-out value is set at Logical Device 8, CR[F6h]. Writing zero disables
the Watchdog Timer function. Writing any non-zero value to this register causes the counter to load
this value into the Watchdog Timer counter and start counting down.
The W83627UHG outputs a low signal to the WDTO# pin (pin 77) when a time-out event occurs. In
other words, when the value is counted down to zero, the timer stops, and the W83627UHG sets the
WDTO# status bit in Logical Device 8, CR[F7h], bit[4], outputting a low signal to the WDTO# pin(pin
77). Writing a zero will clear the status bit and the WDTO# pin returns to high. Writing a zero will clear
the status bit. This bit will also be cleared if LRESET# or PWROK# signal is asserted.
Please note that the output type of WDTO# (pin 77) is open-drain.
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