W83627DHG-PT Nuvoton Technology Corporation of America, W83627DHG-PT Datasheet - Page 198

• Manufacturer Part Number: W83627DHG-PT
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W83627DHG-PT

• Pin Count: 128
• Lead Free Status / RoHS Status: Compliant

W83627DHG-P/W83627DHG-PT
17. WATCHDOG TIMER
The WDTO# pin is a multi-function pin with GP50 functions and is configured to the WDTO# function,
if Configuration Register CR [2Dh], bit 0 is set to zero.
The Watchdog Timer of the W83627DHG-P 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 W83627DHG-P 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 W83627DHG-P 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.
Additionally, GP40 (pin 85), GP42 (pin 83), GP44 (pin 81) and GP46 (pin 79) provides an alternative
WDTO# function. This function can be configured by the relative GPIO control register.
Please note that the output type of WDTO# (pin 77) and GP42 (pin 83) is push-pull and that of GP40
(pin 85), GP44 (pin 81) and GP46 (pin 79) is open-drain.
Publication Release Date: July 09, 2009
-188-
Version 1.94