_______________Detailed Description
The MAX6305–MAX6313 CMOS microprocessor (µP)
supervisory circuits are designed to monitor more than
one power supply and issue a system reset when any
monitored supply falls out of regulation. The MAX6305/
MAX6308/MAX6311 have two adjustable undervoltage
reset inputs (RST IN1 and RST IN2). The MAX6306/
MAX6307/MAX6309/MAX6310/MAX6312/MAX6313 mon-
itor V
CC
through an internal, factory-trimmed voltage
divider. The MAX6306/MAX6309/MAX6312 have, in
addition, an adjustable undervoltage reset input and a
manual-reset input. The internal voltage divider sets the
reset threshold as specified in the device part number
(Table 1). The MAX6307/MAX6310/ MAX6313 feature an
adjustable undervoltage reset input (RST IN) and an
adjustable overvoltage reset input (OVRST IN) in addition
to the factory-trimmed reset threshold on the V
CC
moni-
tor. Program the adjustable reset inputs with an external
resistor divider (see
Adjustable Reset Inputs
section).
Reset Outputs
A µP’s reset input starts the µP in a known state. These
µP supervisory circuits assert reset to prevent code-
execution errors during power-up, power-down, or
brownout conditions.
RESET (MAX6305–MAX6310) and RESET (MAX6311/
MAX6312/MAX6313) are guaranteed to be asserted at
a valid logic level for V
CC
> 1V (see
Electrical
Characteristics
). Once all monitored voltages exceed
their programmed reset thresholds, an internal timer
keeps reset asserted for the reset timeout period (t
RP
);
after this interval, reset deasserts.
If a brownout condition occurs (any or all monitored volt-
ages dip outside their programmed reset threshold),
reset asserts (RESET goes high; RESET goes low). Any
time any of the monitored voltages dip below their reset
threshold, the internal timer resets to zero and reset
asserts. The internal timer starts when all of the moni-
tored voltages return above their reset thresholds, and
reset remains asserted for a reset timeout period. The
MAX6305/MAX6306/MAX6307 feature an active-low,
MAX6305–MAX6313
5-Pin, Multiple-Input,
Programmable Reset ICs
5
______________________________________________________________Pin Description
MAX6305
MAX6308
MAX6311
NAME FUNCTION
Active-Low, Open-Drain Reset Output for the MAX6305/MAX6306/
MAX6307. Active-Low, Push/Pull Reset Output (sources and sinks
current) for the MAX6308/MAX6309/MAX6310.
1
RESET Active-High, Push/Pull Reset Output for the MAX6311/MAX6312/MAX6313
2 GND System Ground
— OVRST IN
Overvoltage Reset Comparator Input. Asserts reset when the monitored
voltage exceeds the programmed threshold. Set the reset threshold
with an external resistor divider. Connect to GND if unused.
— RST IN
Undervoltage Reset Comparator Input. Asserts reset when the
monitored voltage falls below the programmed threshold. Set the
reset threshold with an external resistor divider. Connect to V
CC
if
unused.
3, 4
RST IN1,
RST IN2
—
MR
Manual-Reset Input. Pull low to force a reset. RESET/RESET remains
active as long as MR is low and for the timeout period after MR
goes high. Leave unconnected or connect to V
CC
if unused.
5 V
CC
System Supply. The MAX6306/MAX6307/MAX6309/MAX6310/
MAX6312/MAX6313 also monitor V
CC
through an internal factory-
trimmed resistor divider to the reset comparator.
MAX6306
MAX6309
MAX6312
1
2
—
4
—
3
5
MAX6307
MAX6310
MAX6313
PIN
1
2
4
3
—
—
5
RESET
