MAX6351 Maxim, MAX6351 Datasheet - Page 6

• Manufacturer Part Number: MAX6351
• Description: Dual/Triple-Voltage P Supervisory Circuits
• Manufacturer: Maxim

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 V
output reset state is guaranteed to remain viable while
either V
Dual/Triple-Voltage
µP Supervisory Circuits
Figure 1. Functional Diagram
6
_______________________________________________________________________________________
(5) 6
(5)
(5)
4
2
CC
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 V
V
(RSTIN)
V
(WDI)
GND
5 or V
CC
CC
5
3
CC
FOR THE MAX6352/53/54.
1.22V
V
CC
V
TH
TH
5
3
3 is above +1V.
Detailed Description
CC
5 and V
WATCHDOG
TIMER
MAX6351–MAX6360
Supply Voltages
GENERATOR
CC
MR
RESET
GLITCH
FILTER
3. In addition, the
3
RST3 (5)
RST5
RST (1)
(1)
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.
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
V
low reset-output state. The reset outputs are maintained
as long as either supply is above +1V.
The MAX6351–MAX6360 are designed to ignore short
negative-going V
Operating Characteristics for a glitch immunity graph.
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 V
Note that RSTIN is powered by V
must therefore remain lower than V
Figure 2. Monitoring a Third Voltage
CC
5 and V
V3
V
CC
5 V
CC
V
Negative-Going V
3 maintain the sinking capability of the
3TH
RSTIN
(MAX6355/MAX6356/MAX6357)
CC
5 and V
R1
R2
1.22
RSTIN
CC
R1
MAX6355
MAX6356
MAX6357
Third Input Voltage
3 transients. See Typical
R2
Threshold Levels
CC
CC
R2
3
Reset Outputs
CC
5, and its voltage
5.
is:
Transients