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PDF MAX6449 Data sheet ( Hoja de datos )
| Número de pieza | MAX6449 | |
| Descripción | (MAX6443 - MAX6452) uP Reset Circuits | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX6449 (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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19-2656; Rev 1; 1/03
µP Reset Circuits with Long Manual Reset
Setup Period
General Description
The MAX6443–MAX6452 low-current microprocessor
reset circuits feature single or dual manual reset inputs
with an extended 6.72s setup period. Because of the
extended setup period, short switch closures (nuisance
resets) are ignored.
On all devices, the reset output asserts when any of the
monitored supply voltages drops below its specified
threshold. The reset output remains asserted for the
reset timeout period (210ms typ) after all monitored
supplies exceed their reset thresholds. The reset output
is one-shot pulse asserted for the reset timeout period
(140ms min) when selected manual reset input(s) are
held low for an extended setup timeout period of 6.72s.
These devices ignore manual reset transitions of less
than 6.72s (typ).
The MAX6443–MAX6448 are single fixed-voltage µP
supervisors. The MAX6443/MAX6444 have a single
extended manual reset input. The MAX6445/MAX6446
have two extended manual reset inputs. The MAX6447/
MAX6448 have one extended and one immediate manual
reset input.
The MAX6449–MAX6452 have one fixed-threshold µP
supervisor and one adjustable-threshold µP supervisor.
The MAX6449/MAX6450 have two delayed manual
reset inputs. The MAX6451/MAX6452 have one delayed
and one immediate manual reset input.
The MAX6443–MAX6452 have an active-low RESET
with push-pull or open-drain output logic options. These
devices, offered in small SOT packages, are fully guar-
www.DaantateSehedeto4vUe.crotmhe extended temperature range (-40°C to
+85°C).
Applications
Set-Top Boxes
Consumer Electronics
DVD Players
Modems
MP3 Players
Industrial Equipment
Automotive
Medical Devices
Features
o Single- or Dual-Supply Voltage Monitors
o Precision Factory-Set Reset Thresholds from
1.6V to 4.6V
o Adjustable Threshold to Monitor Voltages Down
to 0.63V (MAX6449–MAX6452)
o Single or Dual Manual Reset Inputs with Extended
6.72s Setup Period
o Optional Short Setup Time Manual Reset Input
(MAX6447/MAX6448 and MAX6451/MAX6452)
o Immune to Short Voltage Transients
o Low 6µA Supply Current
o Guaranteed Valid Reset Down to VCC = 1.0V
o Active-Low RESET (Push-Pull or Open-Drain)
Outputs
o 140ms (min) Reset Timeout Period
o Small SOT143 and SOT23 Packages
Ordering Information
PART
MAX6443 US_ _L -T
MAX6444 US_ _L -T
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
4 SOT143-4
4 SOT143-4
Note: The “_ _ ” is a placeholder for the threshold voltage level
of the devices. A desired threshold level is set by the two-num-
ber suffix found in Table 1. All devices are available in tape-
and-reel only. There is a 2500-piece minimum order increment
for standard versions (Table 2). Sample stock is typically held
on standard versions only. Nonstandard versions require a
minimum order increment of 10,000 pieces. Contact factory for
availability.
Pin Configurations
TOP VIEW
GND 1
RESET 2
MAX6443
MAX6444
4 VCC
3 MR1
SOT143
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
µP Reset Circuits with Long Manual Reset
Setup Period
Pin Description
MAX6443
MAX6444
1
MAX6445
MAX6446
2
PIN
MAX6447
MAX6448
2
MAX6449
MAX6450
2
MAX6451
MAX6452
2
21111
NAME
FUNCTION
GND
RESET
Ground
Active-Low Push-Pull or Open-Drain Output. RESET
changes from high to low when VCC or RSTIN drops below
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 20kΩ pullup resistor to VCC .
Manual Reset Input, Active Low. Internal 50kΩ pullup to
3—3—3
VCC. Pull MR1 low for the typical input pulse width
(6.72s) to one-shot pulse RESET for the reset timeout
MR1 period.
—3—3—
Manual Reset Input, Active Low. Pull both MR1 and
MR2 low for the typical input pulse width (6.72s) to one-
shot pulse RESET for the reset timeout period.
4
4
4
4
4
VCC
VCC Voltage Input. Power supply and input for the
primary microprocessor voltage reset monitor.
Manual Reset Input, Active Low. Internal 50kΩ pullup to
—
5
—
6
—
MR2
VCC. Pull both MR1 and MR2 low for the typical input
pulse width (6.72s) to one-shot pulse RESET for the
www.DataSheet4U.com
reset timeout period.
——
5
—
6
MR2
Manual Reset Input. Pull the MR2 high to immediately
one-shot pulse RESET for the reset timeout period.
———
5
Reset Input. High-impedance input to the adjustable
5
RSTIN
reset comparator. Connect RSTIN to the center point of
an external resistor-divider to set the threshold of the
externally monitored voltage.
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-
tored voltages (RSTIN or VCC) drop below the reset
threshold voltages. Once VRSTIN and VCC exceed their
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
state for VCC inputs ≥ 1V. For applications requiring valid
reset logic when VCC is less than 1V, see the Ensuring a
Valid RESET Output Down to VCC = 0V section.
_______________________________________________________________________________________ 5
5 Page 
µP Reset Circuits with Long Manual Reset
Setup Period
PART
MAX6443
MAX6444
MAX6445
MAX6446
MAX6447
MAX6448
MAX6449
MAX6450
MAX6451
MAX6452
MR1
SETUP
6.72s
6.72s
6.72s
6.72s
6.72s
6.72s
6.72s
6.72s
6.72s
6.72s
MR2
(NO SETUP)
—
—
—
—
✔
✔
—
—
✔
✔
MR2
SETUP
—
—
6.72s
6.72s
—
—
6.72s
6.72s
—
—
*Other timing options may be available. Contact factory for availability.
Selector Guide
RSTIN PUSH-PULL RESET OPEN-DRAIN RESET
—✔
——
—✔
——
—✔
——
✔✔
✔—
✔✔
✔—
—
✔
—
✔
—
✔
—
✔
—
✔
Functional Diagram
VCC
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MAX6449– RSTIN
MAX6452
VCC
1.23V
MAX6443–
MAX6452
RESET
TIMEOUT PERIOD
(210ms typ)
RESET
0.63V
MANUAL RESET
SETUP PERIOD
(6.72s typ)
MR2 ONE-SHOT
DEBOUNCE
CIRCUIT
MAX6447
MR2 MAX6448
MAX6451
MAX6452
VCC
GND
MR1 MR2
MAX6445
MAX6446
MAX6449
MAX6450
VCC
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet MAX6449.PDF ] | |
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