MAX809SEUR+T10 Maxim Integrated Products, MAX809SEUR+T10 Datasheet - Page 6

• Manufacturer Part Number: MAX809SEUR+T10
• Description: IC RESET CIRC MPU SOT23-3
• Manufacturer: Maxim Integrated Products
• Type: Simple Reset/Power-On Resetr

Specifications of MAX809SEUR+T10

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active Low
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 2.93V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-3, TO-236-3, Micro3™, SSD3, SST3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Therefore, high-impedance CMOS logic inputs con-
nected to RESET can drift to undetermined voltages.
This presents no problem in most applications since
most µP and other circuitry is inoperative with V
below 1V. However, in applications where RESET must
be valid down to 0V, adding a pull-down resistor to
RESET causes 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 pullup resistor to V
for the MAX810 if RESET is required to remain valid for
V
3-Pin Microprocessor Reset Circuits
Figure 1. Maximum Transient Duration Without Causing a
Reset Pulse vs. Reset Comparator Overdrive
Figure 3. Interfacing to µPs with Bidirectional Reset I/O
6
CC
V
_______________________________________________________________________________________
CC
< 1V.
MAX803
400
320
240
160
80
GND
V
0
CC
RESET COMPARATOR OVERDRIVE, V
1
MAX8_ _R/S/T/Z
T
A
RESET
= +25°C
10
MAX8_ _J/L/M
CC
is also recommended
100
RESET
INPUT
TH
- V
CC
MOTOROLA
68HCXX
(mV)
GND
V
μP
CC
1000
CC
Since the RESET output on the MAX803 is open drain,
this device interfaces easily with µPs that have bidirec-
tional reset pins, such as the Motorola 68HC11.
Connecting the µP supervisor’s RESET output directly
to the microcontroller’s (µC’s) RESET pin with a single
pullup resistor allows either device to assert reset
(Figure 3).
Generally, the pullup connected to the MAX803 will
connect to the supply voltage that is being monitored at
the IC’s V
open-drain output to level-shift from the monitored sup-
ply to reset circuitry powered by some other supply
(Figure 4). Note that as the MAX803’s V
Figure 2. RESET Valid to V
Figure 4. MAX803 Open-Drain RESET Output Allows Use with
Multiple Supplies
CC
MAX803 Open-Drain RESET Output
MAX803
Allows Use with Multiple Supplies
+3.3V
GND
V
pin. However, some systems may use the
CC
RESET
MAX809
GND
V
CC
RESET
CC
Bidirectional Reset Pins
Interfacing to µPs with
= Ground Circuit
R
PULLUP
RESET
INPUT
R1
100k
5V SYSTEM
CC
+5.0V
GND
V
CC
decreases