MAX6711 MAXIM [Maxim Integrated Products], MAX6711 Datasheet - Page 5

• Manufacturer Part Number: MAX6711
• Description: 4-Pin SC70 Microprocessor Reset Circuits with Manual Reset Input
• Manufacturer: MAXIM [Maxim Integrated Products]

_____________________Pin Description
A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX6711/MAX6712/MAX6713 assert
reset to prevent code-execution errors during power-
up, power-down, or brownout conditions. They assert a
reset signal whenever the V
below a preset threshold, keeping it asserted for at
Figure 1. Maximum Transient Duration Without Causing a
Reset Pulse vs. Reset Comparator Overdrive
PIN
1
2
3
4
(MAX6711/
(MAX6712)
MAX6713)
RESET
RESET
NAME
400
320
240
160
GND
80
V
MR
0
CC
RESET COMPARATOR OVERDRIVE, V
1
MAX671_R/S/T/Z
4-Pin SC70 Microprocessor Reset Circuits
T
A
= +25°C
_______________________________________________________________________________________
Ground
RESET Output remains low while V
is below the reset threshold, and for at
least 140ms after V
reset threshold.
RESET Output remains high while V
is below the reset threshold, and for at
least 140ms after V
reset threshold.
Manual Reset Input. RESET (RESET)
remains asserted as long as MR is low,
and for at least 140ms after MR is
deasserted. This active-low input has
an internal 20kΩ (typ) pull-up resistor.
It can be driven from a TTL- or CMOS-
logic line, or shorted to ground with a
switch. Leave open or connect to V
if unused.
Supply Voltage (+5.0V, +3.3V, +3.0V,
or +2.5V)
Detailed Description
10
MAX671_L/M
CC
FUNCTION
supply voltage declines
100
TH
CC
CC
- V
Reset Output
CC
rises above the
rises above the
(mV)
1000
CC
CC
CC
with Manual Reset Input
least 140ms after V
old. The MAX6713 uses an open-drain output, and the
MAX6711/MAX6712 have a push-pull output stage.
Connect a pull-up resistor on the MAX6713’s RESET
output to any supply between 0 and 6V.
Many µP-based systems require manual reset capabili-
ty, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. Reset remains asserted
while MR is low, and for at least 140ms after MR returns
high. This input has an internal 20kΩ pull-up resistor, so
it can be left open if it is not used. MR can be driven
with TTL- or CMOS-logic levels, or with open-drain/col-
lector outputs. To create a manual reset function, con-
nect a normally open momentary switch from MR to
ground; external debounce circuitry is not required. If
MR is driven from long cables or if the device is used in
a noisy environment, connecting a 0.1µF capacitor from
MR to ground provides additional noise immunity.
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, the MAX6711/
MAX6712/MAX6713 are relatively immune to short-dura-
tion negative-going V
Figure 1 shows typical transient duration vs. reset com-
parator overdrive, for which the MAX6711/MAX6712/
MAX6713 do not generate a reset pulse. The graph was
generated using a negative-going pulse applied to V
starting 0.5V above the actual reset threshold and end-
ing below it by the magnitude indicated (reset compara-
tor overdrive). The graph indicates the maximum pulse
width a negative-going V
causing a reset pulse. As the magnitude of the transient
increases (goes farther below the reset threshold), the
Figure 2. RESET Valid to V
Negative-Going V
Applications Information
MR
CC
CC
MAX6711
has risen above the reset thresh-
CC
GND
V
transients (glitches).
CC
CC
RESET
= Ground Circuit
transient can have without
Manual Reset Input
CC
R1
100k
Transients
CC
5
,