MAX6734KAVFD1-T Maxim Integrated, MAX6734KAVFD1-T Datasheet - Page 12
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MAX6734KAVFD1-T
Manufacturer Part Number
MAX6734KAVFD1-T
Description
Supervisory Circuits
Manufacturer
Maxim Integrated
Series
MAX6730, MAX6731, MAX6732, MAX6733, MAX6734, MAX6735r
Datasheet
1.MAX3182EUKT.pdf
(15 pages)
Specifications of MAX6734KAVFD1-T
Number Of Voltages Monitored
3
Monitored Voltage
0.9 V to 5 V
Undervoltage Threshold
1.53 V, 1.02 V, Adjustable
Overvoltage Threshold
1.62 V, 1.08 V, Adjustable
Output Type
Active Low, Open Drain
Manual Reset
Resettable
Watchdog
Watchdog
Battery Backup Switching
No Backup
Power-up Reset Delay (typ)
1.65 ms
Supply Voltage - Max
5.5 V
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Package / Case
SOT-23
Chip Enable Signals
No
Maximum Power Dissipation
714 mW
Minimum Operating Temperature
- 40 C
Power Fail Detection
No
Supply Current (typ)
15 uA, 4 uA
Supply Voltage - Min
0.8 V
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
Overdrive, for which reset pulses are not generated.
The graph was produced using falling V
starting above V
old by the magnitude indicated (reset threshold over-
drive). The graph shows the maximum pulse width that
a falling V
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
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
_ provides additional transient immunity.
______________________________________________________________________________________
Watchdog Software Considerations
CC
transient typically might have without
SUBROUTINE
COMPLETED
TH
and ending below the reset thresh-
SUBROUTINE OR
PROGRAM LOOP
SET WDI LOW
PROGRAM
SET WDI
RETURN
START
CODE
HIGH
SUBROUTINE
HANG IN
CC
_ pulses,
RSTIN
V
CC
2
V
CC
1
V
REF
V
REF
/ 2
Functional Diagram
MAX6730–
MAX6735
V
REF
CC
1
GND
TIMEOUT
PERIOD
RESET
V
CC
1
MR
V
CC
V
CC
WATCHDOG
1
OUTPUT
1
DRIVER
MR
PULLUP
RESET
TIMER
V
CC
1
V
CC
2
RST
WDO
WDI