Datasheet

Detailed Description
Supply Voltages
The MAX6351–MAX6360 microprocessor (μP) super-
visory circuits maintain system integrity by alerting the
μP to fault conditions. These ICs monitor multiple-supply
systems. The output reset state is guaranteed to remain
viable while either V
CC
1 or V
CC
2 is above +1V.
Threshold Levels
All the possible input voltage threshold-level combina-
tions are indicated by a two-letter code in the Voltage
Threshold Levels table.
Reset Outputs
The MAX6351 provides two active-low, push-pull reset
outputs, one corresponding to each of its two moni-
tored voltages. The MAX6353/MAX6356/MAX6359 have
an active-low, push-pull reset output that is referenced
to V
CC
1. The MAX6354/MAX6357/MAX6360 have an
active-low, push-pull reset output that is referenced to
V
CC
2. The MAX6352/MAX6355/MAX6358 provide an
active-low open-drain reset. The reset outputs are main-
tained as long as at least one of the supplies is above +1V.
Negative-Going V
CC
Transients
The MAX6351–MAX6360 are designed to ignore short
negative-going V
CC
1 and V
CC
2 transients. See the
Maximum V
CC
Transient Duration vs. Reset Threshold
Overdrive graph in the Typical Operating Characteristics.
Third Input Voltage
(MAX6355/MAX6356/MAX6357)
The MAX6355/MAX6356/MAX6357 provide an additional
input to monitor a third voltage. The threshold voltage at
RSTIN is typically 1.22V. To monitor a voltage higher than
1.22V, connect a resistive divider to the circuit, as shown
in Figure 2. The threshold at V
EXT
is:
EXT_TH
R1 R2
V 1.22V
R2
+

=


Note that RSTIN is powered by V
CC
1, and its voltage
must therefore remain lower than or equal to V
CC
1.
Watchdog Input
(MAX6358/MAX6359/MAX6360)
The MAX6358/MAX6359/MAX6360 include a dual-mode
watchdog timer to monitor μP activity. The flexible timeout
architecture provides a startup mode, allowing compli-
cated systems to complete lengthy boots, and a normal
mode, allowing the supervisor to provide quick alerts
when processor activity fails.
Figure 1. Functional Diagram Figure 2. Monitoring a Third Voltage
WATCHDOG
TIMER
V
CC
1(5) 6
4
(5)
(5)
2
GND
NOTE: PIN 1 IS RST1 FOR THE MAX6351 AND RST FOR THE
MAX6352–MAX6360. PIN 5 IS RST2 FOR THE MAX6351, RSTIN
FOR THE MAX6355/MAX6356/MAX6357, WDI FOR THE MAX6358/
MAX6359/MAX6360, AND V
CC
1 FOR THE MAX6352/MAX6353/MAX6354.
V
CC
2
MR
(RSTIN)
RST (1)
RST2 (5)
(1)RST1
(WDI)
RESET
GENERATOR
GLITCH
FILTER
MAX6351–MAX6360
V
TH
1
V
TH
2
1.22V
3
V
EXT
R1
R2
V
CC
1 ≥ V
RSTIN
RSTIN
MAX6355
MAX6356
MAX6357
MAX6351–MAX6360 Dual/Triple-Voltage
μP Supervisory Circuits
www.maximintegrated.com
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