MAX6733AUTRFD4+T Maxim Integrated, MAX6733AUTRFD4+T Datasheet - Page 12

• Manufacturer Part Number: MAX6733AUTRFD4+T
• Description: Supervisory Circuits Single-/Dual-/Triple-Voltage N
• Manufacturer: Maxim Integrated
• Series: MAX6730A, MAX6731A, MAX6732A, MAX6733A, MAX6734A, MAX6735Ar

Specifications of MAX6733AUTRFD4+T

• Number Of Voltages Monitored: 2
• Monitored Voltage: 0.9 V to 5 V
• Undervoltage Threshold: 4.5 V, 3 V
• Manual Reset: Not Resettable
• Watchdog: Watchdog
• Supply Voltage - Max: 5.5 V
• Maximum Power Dissipation: 696 mW
• Supply Current (typ): 15 uA
• Supply Voltage - Min: 0.8 V

Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Threshold Overdrive graph, for which reset pulses are
not generated. The graph was produced using falling
V
reset threshold by the magnitude indicated (reset
threshold overdrive). The graph shows the maximum
pulse width that a falling V
have without causing a reset pulse to be issued. As the
amplitude of the transient increases (i.e., goes further
below the reset threshold), the maximum allowable
pulse width decreases. A 0.1µF bypass capacitor
mounted close to V
immunity.
Setting and resetting the watchdog input at different
points in the program rather than “pulsing” the watch-
dog input high-low-high or low-high-low helps the
watchdog timer closely monitor software execution.
This technique avoids a “stuck” loop, in which the
watchdog timer continues to be reset within the loop,
preventing the watchdog from timing out. Figure 6
shows an example flow diagram in which the I/O dri-
ving the watchdog input is set high at the beginning of
the program, set low at the beginning of every subrou-
tine or loop, and then set high again when the program
returns to the beginning. If the program “hangs” in any
subroutine, the I/O continually asserts low (or high),
and the watchdog timer expires, issuing a reset or
interrupt.
12
Figure 6. Watchdog Flow Diagram
CC
_ pulses, starting above V
______________________________________________________________________________________
Watchdog Software Considerations
SUBROUTINE
COMPLETED
CC
SUBROUTINE OR
PROGRAM LOOP
SET WDI LOW
_ provides additional transient
PROGRAM
SET WDI
RETURN
START
CODE
HIGH
CC
TH
transient typically might
SUBROUTINE
and ending below the
HANG IN
RSTIN
V
CC
2
V
CC
1
V
V
REF
REF
/ 2
Functional Diagram
MAX6730A–
MAX6735A
V
REF
CC
1
GND
TIMEOUT
PERIOD
RESET
V
CC
1
MR
V
CC
V
CC
WATCHDOG
1
OUTPUT
DRIVER
1
MR
PULLUP
RESET
TIMER
V
CC
1
V
CC
2
RST
WDO
WDI