MAX6730A MAXIM [Maxim Integrated Products], MAX6730A Datasheet - Page 9

• Manufacturer Part Number: MAX6730A
• Description: Single-/Dual-/Triple-Voltage ?P Supervisory Circuits with Independent Watchdog Output
• Manufacturer: MAXIM [Maxim Integrated Products]

Many µP-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. A logic-low on MR
asserts the reset output, clears the watchdog timer,
and deasserts the watchdog output. Reset remains
asserted while MR is low and for the reset timeout peri-
od (t
resistor allows MR to be left open if unused. Drive MR
with CMOS-logic levels or with open-drain/collector out-
puts. Connect a normally open momentary switch from
MR to GND to create a manual reset function; external
debounce circuitry is not required. Connect a 0.1µF
capacitor from MR to GND to provide additional noise
immunity when driving MR over long cables or if the
device is used in a noisy environment.
The MAX6734A/MAX6735A provide an additional high-
impedance comparator input with a 626mV threshold to
monitor a third supply voltage. To monitor a voltage
higher than 626mV, connect a resistive divider to the
circuit as shown in Figure 2 to establish an externally
controlled threshold voltage, V
Figure 1.
RSTIN
RP
V
V
WDO
CC
RST
CC
MR
1,
) after MR returns high. An internal 50kΩ pullup
2
RST , WDO , and MR Timing Diagram
Circuits with Independent Watchdog Output
V
EXT_TH
Adjustable Input Voltage (RSTIN)
Single-/Dual-/Triple-Voltage µP Supervisory
(MIN)
V
CC
_______________________________________________________________________________________
= 626mV
V
TH
t
RP
EXT_TH
Manual Reset Input
×
(
R
1
R
+
.
2
R
2
)
t
Figure 2. Monitoring a Third Voltage
RP
R1
R2
V
EXT_TH
RSTIN
MAX6734A
MAX6735A
GND
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