Datasheet

MAX6730–MAX6735
Single-/Dual-/Triple-Voltage µP Supervisory
Circuits with Independent Watchdog Output
11
Maxim Integrated
Applications Information
Interfacing to µPs with Bidirectional
Reset Pins
Microprocessors with bidirectional reset pins can inter-
face directly with the open-drain RST output options.
However, conditions might occur in which the push-pull
output versions experience logic contention with the
bidirectional reset pin of the µP. Connect a 10kΩ resis-
tor between RST and the µP’s reset I/O port to prevent
logic contention (Figure 5).
Falling V
CC
Transients
The MAX6730–MAX6735 µP supervisors are relatively
immune to short-duration falling V
CC
_ transients (glitch-
es). Small glitches on V
CC
_ are ignored by the
MAX6730–MAX6735, preventing undesirable reset
pulses to the µP. The Typical Operating Characteristics
show Maximum Transient Duration vs. Reset Threshold
t
RP
> t
WD-S
t
MR
< t
WD-S
< t
WD-L
< t
WD-L
t
RP
V
TH
V
CC
(MIN)
V
CC
1,
V
CC
2
RSTIN
RST
WDO
WDI
MR
Figure 4. Watchdog Input/Output Timing Diagram (MR and WDO Connected)
MAX6731
MAX6733
MAX6735
V
CC
1
V
CC
1
V
CC
2
V
CC
2
RESET TO
OTHER
SYSTEM
COMPONENTS
GND
μ P
RST
GND
10k
Ω
RESET
Figure 5. Interfacing to µPs with Bidirectional Reset I/O