MPQ6411―WINDOWED WATCHDOG TIMER, AEC-Q100 QUALIFIED
PRELIMINARY SPECIFICATIONS SUBJECT TO CHANGE
MPQ6411 Rev. 1.1 www.MonolithicPower.com 13
6/16/2017 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2017 MPS. All Rights Reserved.
OPERATION
Supply Voltage
VCC= 5V10% is recommended for MPQ6411
/MPQ6411-AEC1 normal operation; while
VCC= 3.3V10% is recommended for
MPQ6411-33/MPQ6411-33-AEC1 normal
operation. WDO is pulled low when VCC rises
to 1V or above. After VCC rises to 90%
(typically), WDO will remain at a low level for t
0
to reset the MCU.
TIMER
Period T (s):
TIMER
T s 15.75 R k 73.5
R
TIMER
(k):
TIMER
R k 0.063 T s 4.67
For example: R
TIMER
=51kΩ, T0.88ms
Monitor MCU Synchronization Signal
When the watchdog is in a “sync signal
monitoring state,” the following will occur:
If the watchdog IC receives a WDI_OK
signal from the MCU within t
1
(WDI remains
low for 10µs to 5ms), the timer will be reset,
and the watchdog works in normal
operation.
If the watchdog does not receive the
WDI_OK signal from the MCU during t
1
, it
will generate a reset signal and go into
“sync signal monitor state” again.
Short Window Mode
If the MCU and watchdog are synchronized
correctly and MODE is low, the watchdog will
work in short window mode:
If WDI_OK is received in a window close
state (t
2
), the watchdog outputs a reset
signal and goes into a sync signal
monitoring state.
If WDI_OK is received in a window open
state (t
3
), the watchdog goes into a window
close state. The MCU works in normal
operation in this situation.
If no WDI_OK signal is received in t
2
+t
3
, the
watchdog outputs a reset signal and goes
into a sync signal monitoring state.
If MODE is pulled high during short window
mode, the watchdog will go into long
window mode.
Long Window Mode
If the MCU and watchdog are synchronized
correctly and MODE is high, the watchdog will
operate in long window mode, and the following
will occur:
If WDI_OK is received in a window close
state (t
4
), the watchdog outputs a reset
signal and goes into a sync signal
monitoring state.
If WDI_OK is received in a window open
state (t
5
), the watchdog goes into a window
close state. The MCU works in normal
operation in this situation.
If no WDI_OK signal is received in t
4
+t
5
, the
watchdog outputs a reset signal and goes
into a sync signal monitoring state.
If MODE is pulled low during a long window
mode, the watchdog will go into a short
window mode.
Watchdog Disable
Pull /WD_DIS low to disable the watchdog; pull
it high to enable the watchdog. /WD_DIS has a
weak internal pull-up, so the watchdog is
enabled if /WD_DIS is left open.
WDI Error
If a WDI signal remains at a low level for longer
than the maximum WDI_OK pulse width, it is
regarded as an error. When this error occurs,
WDO is pulled down until WDI returns to a high
level.
