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PDF MAX6467 Data sheet ( Hoja de datos )
| Número de pieza | MAX6467 | |
| Descripción | Microprocessor Supervisory Reset Circuits with Edge-Triggered / One-Shot Manual Reset | |
| Fabricantes | Maxim Integrated | |
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Hay una vista previa y un enlace de descarga de MAX6467 (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
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19-2523; Rev 0; 7/02
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
General Description
The MAX6467/MAX6468 microprocessor (µP) supervi-
sory circuits monitor single power-supply voltages from
+1.8V to +5.0V and assert a reset if the supply voltage
drops below its preset threshold. An edge-triggered,
one-shot manual reset function ensures that the µP
enters the reset mode for a fixed timeout period only,
even in the event of a continuously asserted manual
reset. The MAX6467/MAX6468 significantly improve
system reliability compared to traditional manual reset
supervisory circuits.
A variety of factory-trimmed threshold options accommo-
date different supply voltages and tolerances, eliminating
external components. The factory-set thresholds range
from +1.575V to +4.625V to monitor +5.0V, +3.3V, +3.0V,
+2.5V, and +1.8V supplies with various tolerances. Reset
timeout periods of 150ms (min) and 1200ms (min) are
available to accommodate different µP platforms.
A single, active-low RESET output asserts when VCC
drops below its threshold or if the edge-triggered MR
asserts low. RESET remains low for the reset timeout
period after VCC rises above its threshold and for a fixed,
one-shot timeout period after a manual reset input falling
edge. RESET remains valid as long as VCC remains
above +1V. Open-drain (MAX6467) and push-pull
(MAX6468) output options provide additional flexibility in
the system design.
The MAX6467/MAX6468 are offered in the space-saving
4-pin SOT143 package and the ultra-small 4-pin SC70
package and are specified over the automotive (-40°C to
+125°C) temperature range.
Applications
Cell Phones/PDAs
Embedded Control Systems
Industrial Equipment
Automotive Products
Portable/Battery-Powered Equipment
Medical Devices
DSL Modems
MP3 Players
GPS Systems
Digital Cameras
Features
o Precision Factory-Set Reset Threshold Voltages
for +5.0V, +3.3V, +3.0V, +2.5V, and +1.8V Supplies
o Edge-Triggered Manual Reset Input with One-
Shot Pulsed Reset Output
o Two Reset Timeout Period Options (150ms or
1200ms min)
o Immune to Short Voltage Transients
o Low Supply Current (3µA at VCC = +1.8V)
o RESET Valid to VCC = +1V
o Active-Low Open-Drain and Push-Pull RESET
Output Options
o -40°C to +125°C Operating Temperature Range
o Small 4-Pin SC70 and SOT143 Packages
o No External Components Required
o Pin Compatible with MAX811, MAX6315,
MAX6384, and MAX6386
Ordering Information
PART
MAX6467XS_ _D_-T
MAX6467US_ _D_-T
MAX6468XS_ _D_-T
MAX6468US_ _D_-T
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
4 SC70-4
4 SOT143-4
4 SC70-4
4 SOT143-4
Note: Insert reset threshold suffix (see Reset Threshold table)
after XS or US. Insert reset timeout delay (see Reset Timeout
Delay table) after D to complete the part number. Sample stock
is generally held on standard versions only (see Standard
Versions table). Standard versions have an order increment
requirement of 2500 pieces. Nonstandard versions have an
order increment requirement of 10,000 pieces. Contact factory
for availability.
Pin Configurations
TOP VIEW
GND 1
RESET 2
MAX6467XS
MAX6468XS
4 VCC
3 MR
SC70
Typical Operating Circuit appears at end of data sheet.
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  
Microprocessor Supervisory Reset Circuits
with Edge-Triggered, One-Shot Manual Reset
Pin Description
PIN NAME
FUNCTION
1 GND Ground
Reset Output. RESET is an active-low open-drain (MAX6467) or push-pull (MAX6468) output. RESET asserts
2
RESET
low when VCC drops below the selected threshold and remains low for the VCC reset timeout period after
VCC rises above the threshold. The RESET one-shot asserts low for a fixed MR reset timeout period on the
falling edge of the manual reset input. The open-drain output requires an external pullup resistor.
Manual Reset Input. Drive MR low to initiate a reset output. MR controls an edge-triggered one-shot that
3 MR asserts RESET low for a fixed MR timeout period when MR is driven low. Internal timing circuitry ignores
switch close and open bounce to ensure proper one-shot reset timing.
Power-Supply Input. VCC provides power to the device and is also a monitored voltage. When VCC drops
4 VCC below the selected threshold, RESET asserts low and remains low for the reset timeout period after VCC rises
above the threshold. For better noise immunity, bypass VCC to GND with a 0.1µF capacitor.
VCC
VTH
GND
SWITCH
SWITCH
SWITCH
BOUNCE
BOUNCE
BOUNCE
MR
GND
RESET
tRP
tMRP
tDEB tMRP
GND
Figure 1. Timing Diagram
Detailed Description
Reset Output
The MAX6467 provides an active-low open-drain
RESET output. The MAX6468 provides an active-low
push-pull RESET output. RESET asserts low if VCC
drops below the selected threshold or if a falling edge
occurs on MR. RESET remains low for the VCC reset
timeout period after VCC increases above the threshold
voltage or is one-shot pulsed low for the MR timeout
period after a falling edge on MR.
Manual Reset Input
Many µP-based products require manual reset capability,
allowing the operator, a test technician, or external logic
circuitry to initiate a reset. A falling edge on MR asserts
RESET low. RESET is one-shot pulsed low for the MR
timeout period after a falling edge on MR. An internal
1.5kΩ pullup resistor to VCC allows MR to be left uncon-
nected if not used. MR can be driven with TTL or CMOS-
logic levels, or with open-drain/collector outputs. Connect
a normally open momentary pushbutton switch from MR
to GND to realize a manual reset function. External
debounce circuitry is not required, as the MAX6467/
MAX6468 respond to the first falling edge on MR and
ignore subsequent falling edges within the reset timeout
period and during the MR debounce period (see Figure
1). After MR goes high for 150ms (tDEB), the manual reset
one-shot is ready to trigger a reset on the next MR falling
edge. Connect a 0.1µF capacitor from MR to GND when
using long cables to provide additional noise immunity
(Figure 2).
_______________________________________________________________________________________ 5
5 Page | ||
| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet MAX6467.PDF ] | |
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