MAX6823YUK+T Maxim Integrated Products, MAX6823YUK+T Datasheet - Page 5

• Manufacturer Part Number: MAX6823YUK+T
• Description: IC MPU SUPERVISOR SOT23-5
• Manufacturer: Maxim Integrated Products
• Type: Simple Reset/Power-On Resetr

Specifications of MAX6823YUK+T

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active Low
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 2.19V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A µP’s reset input starts the µP in a known state. The
MAX6821–MAX6825 µP supervisory circuits assert a
reset to prevent code-execution errors during power-
up, power-down, and brownout conditions. Whenever
V
asserts low for RESET and high for RESET. Once V
exceeds the reset threshold, an internal timer keeps the
reset output asserted for the specified reset timeout
period (t
original state (see Figure 2).
Many µP-based products require manual reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. On the MAX6821/
MAX6822/MAX6823/MAX6825, a logic low on MR
asserts a reset. Reset remains asserted while MR is
low, and for the timeout period (140ms min) after it
MAX6821 MAX6822 MAX6823 MAX6824 MAX6825
CC
1
2
3
4
5
falls below the reset threshold, the reset output
RP
); after this interval, reset output returns to its
1
2
3
4
5
PIN NUMBERS
_______________________________________________________________________________________
Low-Voltage SOT23 µP Supervisors with
Detailed Description
1
2
3
4
5
RESET /RESET Output
Manual Reset Input
Manual Reset and Watchdog Timer
1
3
2
4
5
1
3
2
4
5
RESET
RESET
NAME
GND
WDI
V
PIN
MR
CC
CC
Active-Low Open-Drain or Push-Pull Reset Output. RESET
changes from high to low when the V
selected reset threshold, MR is pulled low, or the watchdog
triggers a reset. RESET remains low for the reset timeout period
after V
high, or the watchdog triggers a reset.
Active-High Push-Pull Reset Output. RESET changes from low to
high when the V
MR is pulled low, or the watchdog triggers a reset. RESET remains
high for the reset timeout period after V
reset threshold, MR goes low to high, or the watchdog triggers a
reset.
Ground
Active-Low Manual Reset Input. Internal 50kΩ pullup to V
low to force a reset. Reset remains active as long as MR is low
and for the reset timeout period after MR goes high. Leave
unconnected or connect to V
Watchdog Input. If WDI remains high or low for longer than the
watchdog timeout period, the internal watchdog timer runs out and
a reset is triggered for the reset timeout period. The internal
watchdog timer clears whenever reset is asserted, the manual
reset is asserted, or WDI sees a rising or falling edge. If WDI is
left unconnected or is connected to a three-stated buffer output,
the watchdog feature is disabled.
Supply Voltage and Input for Reset Threshold Monitor
returns high. MR has an internal 50kΩ pullup resistor,
so it can be left open if not used. This input can be dri-
ven with CMOS logic levels or with open-drain/collector
outputs. Connect a normally open momentary switch
from MR to GND to create a manual reset function;
external debounce circuitry is not required. If MR is dri-
ven from long cables or the device is used in a noisy
environment, connect a 0.1µF capacitor from MR to
GND to provide additional noise immunity.
In the MAX6821–MAX6824, the watchdog circuit moni-
tors the µP’s activity. If the µP does not toggle (low to
high or high to low) the watchdog input (WDI) within the
watchdog timeout period (1.6s nominal), reset asserts
for the reset timoeout period. The internal 1.6s timer
can be cleared by either a reset pulse or by toggling
WDI. The WDI can detect pulses as short as 50ns.
While reset is asserted, the timer remains cleared and
does not count. As soon as reset is released, the timer
starts counting (see Figure 3).
CC
exceeds the device reset threshold, MR goes low to
CC
input drops below the selected reset threshold,
FUNCTION
CC
if unused.
CC
CC
Pin Description
input drops below the
exceeds the device
Watchdog Input
CC
. Pull
5