MAX812LEUS-T Maxim Integrated Products, MAX812LEUS-T Datasheet - Page 6

• Manufacturer Part Number: MAX812LEUS-T
• Description: IC MPU V-MONITOR 4.63V SOT143-4
• Manufacturer: Maxim Integrated Products
• Type: Simple Reset/Power-On Resetr

Specifications of MAX812LEUS-T

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active High
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 4.63V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-143, SOT-143B, TO-253AA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: MAX812LEUST; Q1162903C

__________ Applications Information
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, the MAX811/
MAX812 are relatively immune to short duration nega-
tive-going V
Figure 1 shows typical transient durations vs. reset
comparator overdrive, for which the MAX811/MAX812
do not generate a reset pulse. This graph was generat-
ed using a negative-going pulse applied to V
ing above the actual reset threshold and ending below
it by the magnitude indicated (reset comparator over-
drive). The graph indicates the typical maximum pulse
width a negative-going V
causing a reset pulse to be issued. As the magnitude
of the transient increases (goes farther below the reset
threshold), the maximum allowable pulse width
decreases. Typically, a V
below the reset threshold and lasts 40µs or less
(MAX81_L/M) or 20µs or less (MAX81_T/S/R) will not
cause a reset pulse to be issued. A 0.1µF capacitor
mounted as close as possible to V
tional transient immunity.
4-Pin µP Voltage Monitors
with Manual Reset Input
Figure 1. Maximum Transient Duration without Causing a
Reset Pulse vs. Comparator Overdrive
6
_______________________________________________________________________________________
CC
8
7
6
5
4
3
2
1
0
RESET COMPARATOR OVERDRIVE , V
Negative-Going V
transients (glitches).
1
T
MAX81 _L/M
A
= +25°C
MAX81 _R/S/T
10
CC
CC
transient may have without
transient that goes 125mV
100
CC
TH
CC
- V
provides addi-
CC
Transients
(mV)
1000
CC
, start-
When V
no longer sinks current—it becomes an open circuit.
Therefore, high-impedance CMOS-logic inputs con-
nected to the RESET output can drift to undetermined
voltages. This presents no problem in most applica-
tions, since most µP and other circuitry is inoperative
with V
RESET output must be valid down to 0V, adding a pull-
down resistor to the RESET pin will cause any stray
leakage currents to flow to ground, holding RESET low
(Figure 2). R1’s value is not critical; 100kΩ is large
enough not to load RESET and small enough to pull
RESET to ground.
A 100kΩ pull-up resistor to V
for the MAX812 if RESET is required to remain valid for
V
Figure 2. RESET Valid to V
CC
< 1V.
CC
CC
below 1V. However, in applications where the
falls below 1V, the MAX811 RESET output
Ensuring a Valid RESET Output
MAX811
GND
V
CC
CC
RESET
= Ground Circuit
CC
Down to V
is also recommended
R1
CC
= 0V