µP Reset Circuits with Long Manual Reset

Setup Period

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5

Detailed Description

Reset Output

The reset output is typically connected to the reset

input of a microprocessor (µP). A µP’s reset input starts

or restarts the µP in a known state. The MAX6443–

MAX6452 µP supervisory circuits provide the reset

logic to prevent code-execution errors during power-

up, power-down and brownout conditions (see the

Typical Operating Circuit).

RESET changes from high to low whenever the moni-

respective reset threshold voltages, RESET remains low

for the reset timeout period and then goes high. RESET

is one-shot pulsed whenever selected manual reset

inputs are asserted. RESET stays asserted for the nor-

mal reset timeout period (140ms min).

RESET is guaranteed to be in the proper output logic

Pin Description

PIN

MAX6443

MAX6444

MAX6445

MAX6446

MAX6447

MAX6448

MAX6449

MAX6450

MAX6451

MAX6452

NAME

FUNCTION

1

2

2

2

2

GND

Ground

21

11

1

RESET

Active-Low Push-Pull or Open-Drain Output. RESET

its selected reset threshold and remains low for the 210ms

reset timeout period after all monitored power-supply inputs

exceed their selected reset thresholds. RESET is one-shot

pulsed low for the reset timeout period (140ms min) after

selected manual reset inputs are asserted longer than the

specified setup period. For the open-drain output, use a

minimum 20k

3—3—3

Manual Reset Input, Active Low. Internal 50k

Ω pullup to

to one-shot pulse RESET for the reset timeout period.

—3

—3

—

MR1

Manual Reset Input, Active Low. Pull both MR1 and

shot pulse RESET for the reset timeout period.

44

44

4

primary microprocessor voltage reset monitor.

—5

—6

—

MR2

Manual Reset Input, Active Low. Internal 50k

Ω pullup to

timeout period.

——

5

—

6

MR2

Manual Reset Input. Pull the MR2 high to immediately

one-shot pulse RESET for the reset timeout period.

—

—

—

5

5

RSTIN

Reset Input. High-impedance input to the adjustable

reset comparator. Connect RSTIN to the center point of

an external resistor-divider to set the threshold of the

externally monitored voltage.