MAX6830SIUT-T Maxim Integrated, MAX6830SIUT-T Datasheet - Page 9

• Manufacturer Part Number: MAX6830SIUT-T
• Description: Supervisory Circuits
• Manufacturer: Maxim Integrated
• Series: MAX6826, MAX6827, MAX6828, MAX6829, MAX6830, MAX6831r

Specifications of MAX6830SIUT-T

• Number Of Voltages Monitored: 2
• Monitored Voltage: 0.9 V to 2.5 V, 1.8 V to 5 V
• Undervoltage Threshold: 2.83 V, 1.343 V
• Overvoltage Threshold: 3.02 V, 1.433 V
• Output Type: Active High, Push-Pull
• Manual Reset: Resettable
• Watchdog: Watchdog
• Battery Backup Switching: No Backup
• Power-up Reset Delay (typ): 320 ms
• Supply Voltage - Max: 5.5 V
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Package / Case: SOT-23
• Chip Enable Signals: No
• Maximum Power Dissipation: 696 mW
• Minimum Operating Temperature: - 40 C
• Power Fail Detection: No
• Supply Current (typ): 10 uA
• Supply Voltage - Min: 1.2 V

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.
The watchdog circuit 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 peri-
od (1.6s nominal), reset asserts for the reset timeout
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 (Figure 4).
Disable the watchdog function by leaving WDI uncon-
nected or by three-stating the driver connected to WDI.
The watchdog input is internally driven low during the
first 7/8 of the watchdog timeout period and high for the
last 1/8 of the watchdog timeout period. When WDI is left
unconnected, this internal driver clears the 1.6s timer
every 1.4s. When WDI is three-stated or unconnected,
Figure 4. Watchdog Timing Relationship
Figure 5. Monitoring a Voltage
Dual Ultra-Low-Voltage SOT23 µP Supervisors
RESET*
*RESET IS THE INVERSE OF RESET.
V
WDI
CC
V
MONITOR
V
t
RST
CC
t
RP
≥ V
_______________________________________________________________________________________
with Manual Reset and Watchdog Timer
RSTIN
R1
R2
RSTIN
MAX6826
MAX6827
MAX6828
Watchdog Input
t
WD
t
RP
the maximum allowable leakage current is 10µA and the
maximum allowable load capacitance is 200pF.
The MAX6826/MAX6827/MAX6828 provide a user
adjustable input to monitor a second voltage. The
threshold voltage at RSTIN is typically 0.63V. To moni-
tor a voltage higher than 0.63V, connect a resistor-
divider to the circuit as shown in Figure 5. The
threshold at V
Note that RSTIN is powered by V
must therefore remain lower than V
The WDI inputs are internally driven through a buffer
and series resistor from the watchdog timer (Figure 1).
When WDI is left unconnected, the watchdog timer is
serviced within the watchdog timeout period by a low-
high-low pulse from the counter chain. For minimum
watchdog input current (minimum overall power con-
sumption), leave WDI low for the majority of the watch-
dog timeout period, pulsing it low-high-low once within
the first 7/8 of the watchdog timeout period to reset the
watchdog timer. If WDI is externally driven high for the
majority of the timeout period, up to 160µA can flow into
WDI.
Since the RESET output on the MAX6828/MAX6831
is open drain, these devices interface easily with µPs
that have bidirectional reset pins, such as the Motorola
68HC11. Connecting the µP supervisor’s RESET output
Figure 6. Interfacing Open-Drain
Bidirectional Reset I/O
GENERATOR
V
RESET
MONITOR TRIP
MAX6828
MAX6831
MONITOR
GND
V
CC
Applications Information
with Bidirectional Reset Pins
Adjustable Reset Thresholds
RESET
_
is:
Watchdog Input Current
=
0 63
.
RESET to µPs with
V
Interfacing to µPs



CC
R
CC
1
.
R
, and its voltage
RESET
+
2
R
GND
V
2
µ
CC
P



9