MAX6354 データシートの表示（PDF） - Maxim Integrated
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MAX6354 Datasheet PDF : 8 Pages
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Dual/Triple-Voltage
µP Supervisory Circuits
Detailed Description
Supply Voltages
The MAX6351–MAX6360 microprocessor (µP) superviso-
ry circuits maintain system integrity by alerting the µP to
fault conditions. These ICs monitor multiple-supply sys-
tems and derive their internal power from the highest volt-
age source present at VCC5 and VCC3. In addition, the
output reset state is guaranteed to remain viable while
either VCC5 or VCC3 is above +1V.
(5) 6 VCC5
3
MR
GLITCH
FILTER
VTH5
4 VCC3
VTH3
(5) (RSTIN)
RST (1)
RESET
RST3 (5)
GENERATOR
RST5 (1)
1.22V
Threshold Levels
All the possible input voltage threshold level combina-
tions are indicated by a two-letter code in Voltage
Threshold Levels. The two standard combinations are
LS and SY. LS parts monitor one +5V ±5% supply and
one +3.3V ±10% supply. SY parts monitor one +3.3V
±10% supply and one +2.5V ±10% supply. The other
combinations also monitor +5V ±10% supplies, +3.3V
±5% supplies, and +3V ±5% supplies.
Reset Outputs
The MAX6351 provides a 5V active-low reset and a 3V
active-low reset. The MAX6353/MAX6356/MAX6359 pro-
vide a 5V active-low push-pull reset and the MAX6354/
MAX6357/MAX6360 provide a 3V active-low push-pull
reset. The MAX6353/MAX6355/MAX6358 provide an
active-low open-drain reset. The higher input voltages of
VCC5 and VCC3 maintain the sinking capability of the
low reset-output state. The reset outputs are maintained
as long as either supply is above +1V.
Negative-Going VCC Transients
The MAX6351–MAX6360 are designed to ignore short
negative-going VCC5 and VCC3 transients. See Typical
Operating Characteristics for a glitch immunity graph.
Third Input Voltage
(MAX6355/MAX6356/MAX6357)
The MAX6355/MAX6356/MAX6357 provide an addition-
al 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 resistor-divider to the circuit as
shown in Figure 2. The threshold at V3 is:
V3TH
=
1.22
R1
+
R2
R2
Note that RSTIN is powered by VCC5, and its voltage
must therefore remain lower than VCC5.
(5) (WDI)
2
GND
WATCHDOG
TIMER
MAX6351–MAX6360
V3
MAX6355
R1
MAX6356
MAX6357
RSTIN
R2
NOTE: PIN 1 IS RST5 FOR THE MAX6351 AND RST FOR THE
MAX6352–MAX6360. PIN 5 IS RST3 FOR THE MAX6351, RSTIN
FOR THE MAX6355/56/57, WDI FOR THE MAX6358/59/60,
AND VCC FOR THE MAX6352/53/54.
Figure 1. Functional Diagram
VCC5 ≥ VRSTIN
Figure 2. Monitoring a Third Voltage
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