MAX6828 MAXIM [Maxim Integrated Products], MAX6828 Datasheet - Page 8

• Manufacturer Part Number: MAX6828
• Description: Dual Ultra-Low-Voltage SOT23 ?P Supervisors with Manual Reset and Watchdog Timer
• Manufacturer: MAXIM [Maxim Integrated Products]

Dual Ultra-Low-Voltage SOT23 µP Supervisors
with Manual Reset and Watchdog Timer
Figure 2. Functional Diagram of V
A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX6826–MAX6831 µP supervisory
circuits assert a reset to prevent code-execution errors
during power-up, power-down, and brownout condi-
tions. Whenever a monitored voltage falls below the
reset threshold, the reset output asserts low for RESET
and high for RESET. Once all monitored voltages
exceed their reset thresholds, an internal timer keeps
the reset output asserted for the specified reset timeout
period (t
original state (Figure 3).
Many µP-based products require manual-reset capabil-
ity, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. A logic low on MR
8
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RP
); after this interval, reset output returns to its
V
WDI
V
MR
CC2
CC
Detailed Description
RESET /RESET Output
CC2
Manual Reset Input
0.63V
TRANSITION
WATCHDOG
DETECTOR
1.26V
V
CC
asserts a reset. Reset remains asserted while MR is
low, and for the timeout period (140ms min) after it
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
Figure 3. Reset Timing Diagram
DELAY GENERATOR
RESET TIMEOUT
WATCHDOG
MAX6829/MAX6830/MAX6831
TIMER
GND
RESET
RESET
V
1V
CC
V
TH
t
t
RP
RP
RESET
OR
RESET
V
TH
1V
t
t
RD
RD