MAX6866UK16D1S+T Maxim Integrated Products, MAX6866UK16D1S+T Datasheet - Page 11

• Manufacturer Part Number: MAX6866UK16D1S+T
• Description: IC MPU SUPERVISOR SOT23-5
• Manufacturer: Maxim Integrated Products
• Type: Simple Reset/Power-On Resetr

Specifications of MAX6866UK16D1S+T

• Number Of Voltages Monitored: 1
• Output: Open Drain or Open Collector
• Reset: Active Low
• Reset Timeout: 10 ms Minimum
• Voltage - Threshold: 1.575V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 3. Detailed Watchdog Input Timing Relationship
A µP’s reset input starts the µP in a known state. The
MAX6854/MAX6855/MAX6856/MAX6858/MAX6860–
MAX6869 µP supervisory circuits assert a reset to prevent
code-execution errors during power-up, power-down, and
brownout conditions. The MAX6854/MAX6855/MAX6856/
MAX6858/MAX6860–MAX6869 reset output is guaranteed
to be valid for V
Whenever V
output asserts low for RESET and high for RESET.
Once V
timer keeps the reset output asserted for the specified
reset timeout period, then after this interval the reset
output deasserts (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. The MAX6854/
MAX6855/MAX6856/MAX6861–MAX6869 feature an
MR input. A logic low on MR asserts a reset. Reset
remains asserted while MR is low and for the timeout
period, t
an internal 10kΩ pullup from MR to V
unconnected or connect to V
driven with CMOS logic levels or with open-drain/col-
lector outputs. Connect a normally open momentary
switch from MR to GND to implement a manual reset
function; external debounce circuitry is not required. If
MR is driven by 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.
*RESET IS THE INVERSE OF RESET.
RESET*
CC
WDI
RP
V
V
, after MR returns high. The devices provide
OV
OV
CC
CC
exceeds the reset threshold, an internal
CC
CC
falls below the reset threshold, the reset
Nanopower µP Supervisory Circuits with
down to 1.1V.
______________________________________________________________________________________
Detailed Description
t
WDI
RESET /RESET Output
CC
Manual Reset Input
Manual Reset and Watchdog Timer
if unused. MR can be
CC
. Leave MR
t
WD
The MAX6864–MAX6869’s watchdog timer circuitry
monitors 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 (t
for the reset timeout period (t
cleared when reset asserts, when manual reset is
asserted, or by a rising or falling edge on WDI. The
watchdog input detects pulses as short as 150ns.
While reset is asserted the watchdog timer does not
count. As soon as reset deasserts, the watchdog timer
resumes counting (Figure 3).
The reset timeout period for the MAX6854/MAX6855/
MAX6856/MAX6858/MAX6860/MAX6864–MAX6869 is
fixed (see Table 4). The MAX6861/MAX6862/MAX6863
feature a reset timeout select input, CT. Connect CT
according to Table 1 to select between the available
10ms and 150ms (min) reset timeout periods. The time-
out period can be changed while a reset timeout period
is in progress, but will not update until the reset timeout
period has expired.
Table 1. MAX6861/MAX6862/MAX6863
Reset Timeout Period Selection
CT CONNECTION
HIGH
LOW
Selecting the Reset Timeout Period
Applications Information
t
RP
MIN
150
10
RP
TYP
225
15
). The internal timer is
Watchdog Input
WDI
MAX
), reset asserts
300
25
UNITS
ms
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